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Linear and nonlinear quantitative structure-property relationship (QSPR) models were developed based on a dataset with 65 polymer-solvent combinations. Seven quantum chemical descriptors, dipole moment, hardness, chemical potential, electrophilicity index, total energy, HOMO and LUMO orbital energies, were calculated with density functional theory at the B3LYP/6-31 G(d) level for polymers and solvents. Considering the strong correlation between intrinsic viscosity and weight, size, shape as well as topological structure of polymers and solvents, topological descriptors were also applied in this work. Meanwhile, the most appropriate polymer structure representation was investigated by considering 1-5 monomeric repeating units. The molecular descriptors were first screened by using the genetic algorithms-multiple linear regression (GA-MLR), with coefficient of determinations ( r 2 ) of 0.78 and 0.83 for the training set and the prediction set, respectively. The support vector machine model (SVM) model based on the selected descriptors subset showed a r 2 value of 0.95 for the training set and 0.93 for the prediction set. All statistical results suggest that the established QSPR models have good predictability. Furthermore, a new test set obtained from the literature was used for further validation. The r 2 values were 0.81 for the MLR model and 0.90 for the SVM model.

Recent nonequilibrium molecular dynamics (NEMD) simulations of mildly entangled C 400 H 802 and moderately entangled C 700 H 1402 linear polyethylene melts undergoing steady shear flow have revealed that several inconsistencies between theory and experiment could be rectified by consideration of the rotational motion of individual polymer chains that occurs at moderate to high flow strengths. In this study, we investigated the configurational dynamics of the individual molecular chains that allow these once-entangled, long-chain molecules to execute retraction/extension semi-periodic cycles in response to the imposed shear via NEMD simulations. Brownian dynamics simulations were also performed to extract dynamical and configurational information about the similar cycles of polymer chain behavior that occur in dilute solutions of macromolecular chain liquids dissolved in low molecular weight solvents. Results revealed that the configurational motions of the individual chains in both melt and solution were essentially the same and governed by a single timescale that scaled exponentially with the magnitude of the shear rate. This configurational motion contained both in-plane and out-of-plane components with respect to the flow-gradient plane, with the out-of-plane component playing a much larger role during the retraction phase of the cycle than during the extension phase. This was determined to be caused by the enhancement of the retraction motion by the out-of-plane entropic Brownian forces; however, these entropic forces were detrimental to the in-plane hydrodynamic diffusive forces during the extension phase of the cycle and were thus suppressed. Consequently, the configuration of a rotating chain was significantly more compact during the retraction stage than during the extension stage, wherein the latter phase most molecules were more preferentially distributed in the flow-gradient plane., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Over the past decade, electrospraying has proven to be a promising method for the preparation of amorphous solid dispersions, an established formulation strategy to improve the oral bioavailability of poorly soluble drug compounds. Due to the lack of fundamental knowledge concerning adequate single nozzle electrospraying conditions, a trial-and-error approach is currently the only option. The objective of this paper is to study/investigate the influence of the different formulation and process parameters, as well as their interplay, on the formation of a stable cone-jet mode as a prerequisite for a reproducible production of monodisperse micro- and nanoparticles. To this purpose, different polymers commonly used in the formulation of solid dispersions were electrosprayed to map out the workable parameter ranges of the process. The experiments evaluate the importance of the experimental parameters as flow rate, electric potential difference and the distance between the tip of the nozzle and collector. Based on this, the type of solvent and the concentration of the polymer solutions, along with their viscosity and conductivity, were identified as determinative formulation parameters. This information is of utmost importance to rationally design further electrospraying methods for the preparation of amorphous solid dispersions., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Even though dilute (unentangled) polymer solutions cannot act as gel-like sieving media, it has been shown that they can be used to separate DNA molecules in capillary electrophoresis. The separation then comes from sporadic, independent DNA–polymer collisions. We study polymer–polymer collisions in nanochannels (i.e., channels that are smaller than the normal size of the polymers), a situation where a polyelectrolyte is forced to migrate "through" isolated uncharged molecules during electrophoresis. We use Langevin dynamics simulations to explore the nature of these collisions and their effect on the net motion of the two polymer chains. We identify several types of collisions, including some that are unique to nanochannels. When the uncharged polymer is much larger than the polyelectrolyte, the system is reminiscent of gel electrophoresis, and we propose a modified empirical reptation model to explain the data, with an orientation factor that depends on the tube diameter. We also observe that the duration of a collision is a non-monotonic function of the polymer size ratio when the two chains are of comparable size, a surprising resonance-like phenomenon, which, combined with the asymmetric nature of molecular conformations during collision, suggests possible ratchet-like mechanisms that could be used to sort polyelectrolytes in nanodevices. [ABSTRACT FROM AUTHOR]

Cytoskeletal gels are engineered prototypes that mimic the contractile behavior of a cell in vitro. They are composed of an active polymer matrix and a liquid solvent. Their contraction kinetics is governed by two dynamic phenomena: mechanotransduction (molecular motor activation) and solvent diffusion. In this paper, we solve the transient problem for the simple case of a thin gel slab in uniaxial contraction under two extreme conditions: motor-limited or slow motor (SM) activation regime, and diffusion-limited or fast motor (FM) activation regime. The former occurs when diffusion is much faster than mechanotransduction, while the latter occurs in the opposite case. We observe that in the SM regime, the contraction time scales as t / t 0 ∼ (λ / λ 0) − 3 , with t 0 being the nominal contraction time, and λ and λ 0 being the final and initial stretches of the slab. t 0 is proportional to 1 / w ˙ , where w ˙ is the average mechanical power generated by the molecular motors per unit reference (dry polymer) volume. In the FM regime, the contraction time scales as t / t 1 ∼ (1 − λ / λ 0) 2 , with t 1 being the nominal contraction time, here proportional to the ratio L 2 / D , where L is the reference (dry polymer) thickness, and D is the diffusivity of the solvent in the gel. The transition between the SM and FM regimes is defined by a characteristic power density w ˙ ∗ , where w ˙ ≪ w ˙ ∗ gives the SM regime and w ˙ ≫ w ˙ ∗ gives the FM regime. Intuitively, w ˙ ∗ is proportional to D / L 2 , where, at a given power density w ˙ , a thinner gel slab (smaller L) or including smaller solvent molecules (higher D) is more likely to be in the SM regime given that solvent diffusion will occur faster than motor activation. [ABSTRACT FROM AUTHOR]

Polymer flooding is a prominent chemical enhanced oil recovery (CEOR) method that involves the injection of polymer solution into the oil reservoirs to improve the sweep efficiency and maximize the ultimate oil recovery. Selecting an appropriate polymer type, molecular weight, and concentration is crucial for success of any polymer flooding project. This paper studies the flow behavior of HPAM-based EOR polymers with different molecular weights through porous media. Dynamic adsorption and injectivity tests were performed through 5 Darcies sandpacks using polymer solutions prepared with low (LM; 8–10 MDa) and high (HM; 20–25 MDa) molecular weight polymers. Polymer solutions with different target viscosity values of 7, 15 and 30 cP were flooded through sandpacks at the reservoir temperature of 80 ºC and pore pressure of 1000 psi. The results showed that HM solutions with different target viscosity have higher polymer retention through sandpacks compared to LM solutions. Furthermore, results of residual resistance factor (RRF) measurements were in line with dynamic adsorption tests results. That is, permeability reduction due to irreversible polymer retention was higher when HM polymer solutions were injected. Furthermore, the results showed that although the resistance factor (RF) and in-situ viscosity of HM and LM polymers are in the same range, however, shear thickening regime becomes pronounced in the case of HM polymer with higher target viscosity. Polymer relaxation time measurements, and consequently, Deborah number calculations were performed to describe the shear thickening behavior by polymers viscoelastic characteristics. Results demonstrate that occurrence of shear thickening regime is controlled by Deborah number which is a function of polymer molecular weight, polymer concentration and injection rate. These results shed light on the importance of the selection of optimal polymer molecular weight and concentration during the design of polymer flooding projects. [ABSTRACT FROM AUTHOR]

We studied the properties of a reaction front that forms in irreversible reaction–diffusion systems with concentration-dependent diffusivities during the synthesis of polymer brushes. A coarse-grained model of the polymerization process during the formation of polymer brushes was designed and investigated for this purpose. In this model, a certain amount of initiator was placed on an impenetrable surface, and the "grafted from" procedure of polymerization was carried out. The system consisted of monomer molecules and growing chains. The obtained brush consisted of linear chains embedded in nodes of a face-centered cubic lattice with excluded volume interactions only. The simulations were carried out for high rafting densities of 0.1, 0.3, and 0.6 and for reaction probabilities of 0.02, 0.002, and 0.0002. Simulations were performed by means of the Monte Carlo method while employing the Dynamic Lattice Liquid model. Some universal behavior was found, i.e., irrespective of reaction rate and grafting density, the width of the reaction front as well as the height of the front show for long times the same scaling with respect to time. During the formation of the polymer layer despite the observed difference in dispersion of chain lengths for different grafting densities and reaction rates at a given layer height, the quality of the polymer layer does not seem to depend on these parameters. [ABSTRACT FROM AUTHOR]

Based on the two-fluid model, we successfully simulated the film casting process of the polymer solution system and observed the unique response wave of the film thickness and the concentration via applying perturbation. We identify that this instability pattern is essentially the product under the coupling effect of viscoelastic stress and osmotic pressure from fluctuations on different scales, which causes it to exhibit biperiodic characteristics. We call this new instability mode known as dual-mode draw resonance instability. Among them, the concentration oscillation predominates, thereby limiting the critical draw ratio Drc of the system. Through sorting out the molecular image of the polymer concentration response to perturbation, the relevant parameters are extracted, and the law of their influence on the Drc further verifies our conclusion and provides guidance for actual production. [ABSTRACT FROM AUTHOR]

The detailed systematic study of aqueous polyacrylamide solutions at different concentrations and different molar concentrations of NaCl solutions along with the dependency at scattering angles 175o and 90o has been performed rigorously using the Dynamic Light Scattering method. Aqueous polymer solutions of different concentrations of polymer as well as at different molar concentrations of NaCl solutions were prepared for the study. Analyses of the correlation functions show the presence of three concentration regions consisting each with the presence of fast and slow modes. Out of three, the one (unentangled semidilute) concentration regime shows the unique morphology of polymer solutions irrespective of the change in polymer concentrations and with the change in NaCl concentrations. Furthermore, the angular dependency results show the presence of amount of heterogeneity of polymer chains in the solutions which quantified from the overall change of stretching parameter of slow mode β (Dilute and entangled region ~ 20%, Unentangled region ~ 7%). [ABSTRACT FROM AUTHOR]

The simulation of polymer solutions often requires the development of methods that accurately include hydrodynamic interactions. Resolution on the atomistic scale is too computationally expensive to cover mesoscopic time and length scales on which the interesting polymer phenomena are observed. Therefore, coarse-graining methods have to be applied. In this work, the solvent is simulated using the well-established multi-particle collision dynamics scheme, and for the polymer, different coarse-graining methods are employed and compared against the monomer resolved Kremer–Grest model by their resulting diffusion coefficients. This research builds on previous work [Ruiz-Franco et al., J. Chem. Phys. 151, 074902 (2019)], in which star polymers and linear chains in a solvent were simulated and two different coarse-graining methods were developed, in order to increase computational efficiency. The present work extends this approach to ring polymers and seeks to refine one of the authors' proposed model: the penetrable soft colloid model. It was found that both proposed models are not well suited to ring polymers; however, the introduction of a factor to the PSC model delivers satisfying results for the diffusion behavior by regulating the interaction intensity with the solvent. [ABSTRACT FROM AUTHOR]

Though the application of photochromic agents onto textile-based surfaces with the help of printing process or padding technique, their usability have been limited due to their low substantivity. In this study, 12 wt% polymer solutions were prepared with use of three different polyvinyl alcohol (PVA) pellets having identical hydrolysis degree but different molecular weights. Electrospinning was performed after addition of 4 wt% photochromic slurry (PCS) into these polymer solutions. Densities of photochromic slurry-loaded polymer solutions were measured and UV-Vis spectrophotometric analysis was performed for each polymer solution. Nanocomposite mats electrospun from these photochromic slurryloaded polymer solutions were characterized by FTIR, FESEM and UV-Vis spectrophotometry analysis in order to observe morphological, structural and photochromic properties. Thickness of these nanocomposite mats were also measured. Increase in polymer molecular weight lead to increase on average fiber diameter and mat thickness but fabrication of large pore-sized mat with high pore size variation. Even the finest nanofiber handling, surface imperfections were observed in nanocomposite mats electrospun from PVA 5-88 having the lowest molecular weight among the studied PVA polymers. PVA 14-88 polymer having moderate molecular weight exhibited optimum characteristic properties due to its appropriate polymer solution density, producibility of nano-scale electrospun fibers, possibility to make a consistent relationship among pore size, nanofiber diameter and photochromic efficiency. When UV-Vis spectrums of PCS loadedpolymer solutions and electrospun mats were compared, electrospinning technique caused to a differentiation in absorbence value, especially in PVA 17-88. [ABSTRACT FROM AUTHOR]

Pure organic films consisting of polypyrrole, polyaniline and a composite of polypyrrole and polyaniline electrodeposited in the ionic liquid EMIM‐TFSI onto mesoporous carbon electrodes are tested for their hydrogen evolution reaction capabilities. The use of these intrinsically conducting polymers is seen as a way of stepping away from expensive and rare metallic catalysts. Co‐polymerisation of polypyrrole and polyaniline in a 1 : 10 ratio in EMIM‐TFSI was found to be doped with the TFSI− anion and be much more active to the hydrogen evolution reaction when compared to pure polymers. Tafel analysis of the composite gave a value of 144 mV/dec indicating that the Volmer step is the rate limiting step. However, stability tests showed an improvement in the composite's overpoential performance for the hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

The non-ionic hydrophobic associative copolymer AANS was synthesized by micellar polymerization using acrylamide (AM), allyl polyoxyethylene ether (APEG400), N-vinyl pyrrolidone (NVP) and stearyl methacrylate (SM) as raw materials, 2, 2'-azobis (2-methylpropionamidine) dihydrochloride (V50) as initiator, sodium dodecyl sulfate (SDS) as surfactant. The temperature resistance, salt resistance and rheological properties of the polymer were tested by viscometer and rheometer. The change of polymer microstructure in salt solution was analyzed by scanning electron microscopy. The viscosity test results showed that when the polymer concentration was higher than CAC, the polymer solution exhibited good salt resistance and presented good salt thickening performance. The effect of temperature on the salt resistance of polymer solution showed different rules. With the increase in temperature, the resistance of the polymer to NaCl decreased gradually, while the resistance of the polymer to CaCl2 increased first and then decreased. The resistance of the polymer to CaCl2 showed a special temperature response. Viscoelastic and shear tests showed that the polymer possessed more robust resistance to extreme sodium chloride concentration than extreme calcium chloride concentration. Micro-morphology and size analysis suggested that the microstructure of the polymer gradually became dense and compact in the salt solution. The results showed that this novel non-ionic hydrophobically associating polymer possessed potential application value in ultra-high salinity reservoirs. [ABSTRACT FROM AUTHOR]

The analysis of the impact of the star polymer topology on depletion interaction potentials, depletion forces, and monomer density profiles is carried out analytically using field theory methods and techniques as well as molecular dynamic simulations. The dimensionless depletion interaction potentials and the dimensionless depletion forces for a dilute solution of ideal star polymers with three and five legs (arms) in a Θ -solvent confined in a slit between two parallel walls with repulsive surfaces and for the case where one of the surfaces is repulsive and the other inert are obtained. Furthermore, the dimensionless layer monomer density profiles for ideal star polymers with an odd number ( f ˜ = 3, 5) of arms immersed in a dilute solution of big colloidal particles with different adsorbing or repelling properties in respect of polymers are calculated, bearing in mind the Derjaguin approximation. Molecular dynamic simulations of a dilute solution of star-shaped polymers in a good solvent with N = 901 (3 × 300 + 1 -star polymer with three arms) and 1501 (5 × 300 + 1 -star polymer with five arms) beads accordingly confined in a slit with different boundary conditions are performed, and the results of the monomer density profiles for the above-mentioned cases are obtained. The numerical calculation of the radius of gyration for star polymers with f ˜ = 3, 5 arms and the ratio of the perpendicular to parallel components of the radius of gyration with respect to the wall orientation for the above-mentioned cases is performed. The obtained analytical and numerical results for star polymers with an odd number ( f ˜ = 3, 5) of arms are compared with our previous results for linear polymers in confined geometries. The acquired results show that a dilute solution of star polymer chains can be applied in the production of new functional materials, because the behavior of these solutions is strictly correlated with the topology of polymers and also with the nature and geometry of confined surfaces. The above-mentioned properties can find extensive practical application in materials engineering, as well as in biotechnology and medicine for drug and gene transmission. [ABSTRACT FROM AUTHOR]

The progress in polymer science and nanotechnology yields new colloidal and macromolecular objects and their combinations, which can be defined as complex polymer materials. The complexity may include a complicated composition and architecture of macromolecular chains, specific intermolecular interactions, an unusual phase behavior, and a structure of a multi-component polymer-containing material. Determination of a relation between the structure of a complex material, the structure and properties of its constituent elements, and the rheological properties of the material as a whole is the subject of structural rheology—a valuable tool for the development and study of novel materials. This work summarizes the author's structural–rheological studies of complex polymer materials for determining the conditions and rheo-manifestations of their micro- and nanostructuring. The complicated chemical composition of macromolecular chains and its role in polymer structuring via block segregation and cooperative hydrogen bonds in melt and solutions is considered using tri- and multiblock styrene/isoprene and vinyl acetate/vinyl alcohol copolymers. Specific molecular interactions are analyzed in solutions of cellulose; its acetate butyrate; a gelatin/carrageenan combination; and different acrylonitrile, oxadiazole, and benzimidazole copolymers. A homogeneous structuring may result from a conformational transition, a mesophase formation, or a macromolecular association caused by a complex chain composition or specific inter- and supramolecular interactions, which, however, may be masked by macromolecular entanglements when determining a rheological behavior. A heterogeneous structure formation implies a microscopic phase separation upon non-solvent addition, temperature change, or intense shear up to a macroscopic decomposition. Specific polymer/particle interactions have been examined using polyethylene oxide solutions, polyisobutylene melts, and cellulose gels containing solid particles of different nature, demonstrating the competition of macromolecular entanglements, interparticle interactions, and adsorption polymer/particle bonds in governing the rheological properties. Complex chain architecture has been considered using long-chain branched polybutylene-adipate-terephthalate and polyethylene melts, cross-linked sodium hyaluronate hydrogels, asphaltene solutions, and linear/highly-branched polydimethylsiloxane blends, showing that branching raises the viscosity and elasticity and can result in limited miscibility with linear isomonomer chains. Finally, some examples of composite adhesives, membranes, and greases as structured polymeric functional materials have been presented with the demonstration of the relation between their rheological and performance properties. [ABSTRACT FROM AUTHOR]

A systematic experimental density and sound velocity measurement was carried out for imidazolium-based ionic liquids (ILs) in pure water and in aqueous solutions of 0.03 w/w of water-miscible polymers with different structures and molar masses at T= (288.15, 293.15, 298.15, 303.15 and 308.15) K and p = 84.5 kPa. The ILs under investigation are 1-butyl-3-methylimidazolium hydrogen sulphate ([C4mim][HSO4]) and 1-butyl-3-methylimidazolium bromide ([C4mim]Br). The effects of temperature, polymer type, and IL anion type on the various volumetric and compressibility properties, such as apparent molar volume, isentropic compressibility, apparent molar isentropic compressibility, and infinite dilution apparent molar properties for transfer of ILs from water to aqueous polymer solution were scrutinised. From the gathered results, ion-water interactions, ion-ion interactions at finite concentration, and water-structure breaking character for aqueous solutions of [C4mim][HSO4] are more considerable than aqueous solutions of [C4mim]Br. However, [C4mim]Br-polymer interactions are more favourable than interactions between [C4mim][HSO4] and the studied polymers. [ABSTRACT FROM AUTHOR]

Hydrogels are of interest for a wide range of applications. The ability to control when the hydrogel degrades can provide beneficial properties such as controlled degradation in the environment or the stimulated release of drugs or cells. Self‐immolative polymers are a class of degradable polymers that undergo complete end‐to‐end depolymerization upon the application of a stimulus. They have been explored for hydrogel development, but the ability to prepare and selectively degrade self‐immolative hydrogels under neutral aqueous conditions has so far been limited. We describe here the preparation of water‐soluble polyglyoxylamides with cross‐linkable pendent azides and their cross‐linking to form hydrogels with 4‐arm poly(ethylene glycol)s having unstrained and strained alkynes using copper‐assisted and strain‐promoted azide‐alkyne click chemistry respectively. The influence of pendent azide density and solution polymer content on the resulting hydrogels was evaluated. A polyglyoxylamide with a 70 : 30 ratio of pendent hydroxyl:azide successfully provided hydrogels with compressive moduli ranging from 1.3–6.3 kPa under copper‐free conditions at 10–20 % (w/w) of polymer in phosphate‐buffered saline. Selective depolymerization and degradation of the hydrogels upon irradiation with light was demonstrated, resulting in reductions in the compressive moduli and the release of depolymerization products that were detected by NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Mechanical stress governs the dynamics of viscoelastic polymer systems and supercooled glass-forming fluids. It was recently established that liquids with long terminal relaxation times are characterized by transiently frozen stress fields, which, moreover, exhibit long-range correlations contributing to the dynamically heterogeneous nature of such systems. Recent studies show that stress correlations and relaxation elastic moduli are intimately related in isotropic viscoelastic systems. However, the origin of these relations (involving spatially resolved material relaxation functions) is non-trivial: some relations are based on the fluctuation-dissipation theorem (FDT), while others involve approximations. Generalizing our recent results on 2D systems, we here rigorously derive three exact FDT relations (already established in our recent investigations and, partially, in classical studies) between spatio-temporal stress correlations and generalized relaxation moduli, and a couple of new exact relations. We also derive several new approximate relations valid in the hydrodynamic regime, taking into account the effects of thermal conductivity and composition fluctuations for arbitrary space dimension. One approximate relation was heuristically obtained in our previous studies and verified using our extended simulation data on two-dimensional (2D) glass-forming systems. As a result, we provide the means to obtain, in any spatial dimension, all stress-correlation functions in terms of relaxation moduli and vice versa. The new approximate relations are tested using simulation data on 2D systems of polydisperse Lennard–Jones particles. [ABSTRACT FROM AUTHOR]

Shear thickening fluids (STFs) have garnered attention as potential enhancers of protective capabilities and for the optimization of Kevlar® armor design. To assess the possible shear thickening properties and potential application in ballistic protection, ten formulations were developed by employing polyethylene glycol (PEG) or polypropylene glycol (PPG), along with fumed silica or Aerosil HDK®. Rheological characterization facilitated the identification of formulations displaying shear thickening behavior. The potential integration of the selected shear thickening fluids (STFs) into Kevlar®-based composites was investigated by studying the impact resistance of Kevlar® soft armor structures. Also, high-velocity impact testing revealed that the distance between aramid layers plays a crucial role in the impact resistance effectiveness of Kevlar®–STF composite structures and that there is a very narrow domain between optimal and undesired scenarios in which STF could facilitate the penetration of Kevlar. The introduction of STF between the Kevlar sheets disrupted this packing and the energy absorption capacity of the material was not improved. Only one formulation (PEG400, Aerosil 27 wt.%) led to a less profound traumatic imprint and stopped the bullet when it was placed between layers no.1 and no.2 from a total of 11 layers of Kevlar XP. These experimental findings align with the modeling and simulation of Kevlar®–STF composites using Ansys simulation software (Ansys® AutoDyn 2022 R2). [ABSTRACT FROM AUTHOR]

The new generation of impact-resistant materials should be lightweight and flexible. For this purpose, various additives, such as shear thickening gels (STG) are synthesized and incorporated into these materials. In this article, it has been tried to develop a new method for synthesizing new shear -thickening gels (n-STG). This new method involves dispersing Polyvinyl alcohol (PVA) solution into the STG polymer matrix. Unlike previous studies that used PDMS, and boric acid as fixed materials in the preparation of STG, this work introduces PVA as a new auxiliary material in the PDMS and boric acid polymer matrix. At first, different percentages of PVA solution in distilled water (DW) were prepared. After a series of experiments, PVA (14%) was well combined with the polymer matrix. In this way, by changing the mass ratio of PVA (14%) to pyroboric acid (P-BA) and PVA (14%) to polydimethylsiloxane (PDMS), 7 values of (1:6) to (7:6) were tested. When the ratio of PVA (14%) to P-BA is greater than 1:6, it lacks STG properties. However, when the ratio of PVA (14%) to PDMS changed from 1:6 to 6:6, shear thickening gel properties were observed and the samples were named n-STG. The maximum shear storage modulus (G'max) of n-STG samples first increases and then decreases, reaching a maximum value of 0.55 MPa. The resilience elasticity test demonstrated that the rebound percentage value of the n-STG-5 sample was 22.6% higher than the STG sample without PVA, due to its higher shear storage modulus. This study showed that PVA in the STG polymer matrix improves polymer chain cross-linking and performance due to its n-STG stimulus–response property. [ABSTRACT FROM AUTHOR]

In the advancement of organic photovoltaics (OPV) toward scale‐up production, how to mitigate the batch instability of electron‐donating polymers originated from varied molecular weights remains a great challenge. By taking into consideration the relationship between the molecular weight of electron‐donating polymers and the relevant critical concentration (c*) of the solution, herein it is demonstrated that the aggregation behavior of the electron‐donating polymers can be tailored through manipulating c* of the polymer solution. It is interesting to note that the excessive aggregation in low‐molecular‐weight fractions can be circumvented while the favorable mixing ratio can be identified. By preparing the binary bulk heterojunction film under c*‐defined conditions for mixed‐molecular‐weight polymers, a notable power conversion efficiency of 19.1% for binary devices is achieved. Of particular importance is that a linear interrelation can be established between the c* for the maximum PCE and c* for the low‐molecular‐weight fraction aggregation, validating those straightforward spectra measurements can accurately and rationally guide the molecular weight mixing of photovoltaic donor polymers, thereby fully harnessing the potent driving force and affinity inherent to the low‐molecular‐weight fractions. These findings offer a straightforward and logical framework for addressing batch variability in the large‐scale production of high‐performance OPV devices. [ABSTRACT FROM AUTHOR]

The widespread use of polymers has made our lives increasingly convenient by offering a more convenient and dependable material. However, the challenge of efficiently decomposing these materials has resulted in a surge of polymer waste, posing environment and health risk. Currently, landfill and incineration treatment approaches have notable shortcomings, prompting a shift towards more eco-friendly and sustainable biodegradation approaches. Biodegradation primarily relies on microorganisms, with research focusing on both solitary bacterial strain and multi-strain communities for polymer biodegradation. Furthermore, directed evolution and rational design of enzyme have significantly contributed to the polymer biodegradation process. However, previous reviews often undervaluing the role of multi-strain communities. In this review, we assess the current state of these three significant fields of research, provide practical solutions to issues with polymer biodegradation, and outline potential future directions for the subject. Ultimately, biodegradation, whether facilitated by single bacteria, multi-strain communities, or engineered enzymes, now represents the most effective method for managing waste polymers. [ABSTRACT FROM AUTHOR]

As temperature and salt-resistant materials, hydrophobically associating polymers can form a reversible spatial network structure through the interaction between their hydrophobic groups, effectively improve the viscosity of the polymer solution through association, and enhance the temperature and salt resistance of the polymer. Hydrophobically associating monomers have different effects on the properties of polymer solutions. Herein, acrylic acid, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid were used as hydrophilic monomers. The three hydrophobic monomers with different carbon chain lengths were prepared by the bromination reaction. Hydrophobic associating polymers DQM1-PAM, DQM2-PAM, and DQM3-PAM were prepared by aqueous solution free-radical polymerization. The structure–activity relationship of the hydrophobic monomers with different carbon chain lengths on polymers was studied. It was confirmed by Fourier-transform infrared spectroscopy and 1H-NMR that the target product was successfully synthesized. Scanning electron microscopy revealed that with increasing hydrophobic carbon chain length, the hydrophobic microarea of molecular aggregation increased, forming a closer spatial network structure. Thermogravimetric and fluorescence tests revealed that with increasing hydrophobic carbon chain length of polymer molecules, the polymerization temperature resistance increased, intermolecular association degree increased, and critical association concentration decreased. Rheological property evaluation revealed that the viscosity of 0.5% polymer DQM1-PAM, DQM2-PAM, and DQM3-PAM was 71.32, 100.21, and 118.79 mPa·s after shearing at 120 °C and 170 s−1 for 1 h. With the increase in the carbon chain length, the retention rate of shear viscosity of polymer in a salt solution increased, showing good salt resistance. Concurrently, the molecular aggregation microarea of a solution with 0.5% polymer, degree of molecular chain action, viscoelasticity of the solution (G' > G''), and thixotropic area all increased. The performance of polymer solution can be improved by modifying hydrophobically associating polymers with long carbon chains, which has a broader application. [ABSTRACT FROM AUTHOR]

Flexible polymers exhibit pronounced drag reduction but weak resistance to mechanical shear, whereas rigid polymers exhibit remarkable resistance to mechanical shear but slightly weaker drag reduction. Therefore, mixing flexible and rigid polymers could offer improvements in comprehensive drag-reduction performance. This letter reports an experimental study on the drag-reduction performance of binary polyacrylamide (PAM) and xanthan gum (XG) solutions with the PAM concentration fixed at 10 ppm. From comparing curves of the drag reduction rate vs Reynolds number and shearing time, 70-ppm XG is the optimal choice for forming a binary polymer solution with 10-ppm PAM. This binary solution also offers drag-reduction effects equivalent to those of a pure 50-ppm PAM solution. Although it decreases with time, the synergistic coefficient still remains much larger than zero. This implies that the positive synergistic effect of the PAM–XG binary solution persists even under long-term shearing. These results offer a fundamental basis for developing high-performance polymer drag reducers. [ABSTRACT FROM AUTHOR]

Polymer products typically present as mixtures with a range of molecular weights, which notably influence the expression of their properties. In this study, a technique is proposed to separate polyethylene glycol (PEG) mixtures of varying molecular weights using metal–organic frameworks (MOFs), thereby narrowing down their molecular weight distribution. Due to the hydrogen bond interactions between PEG and ‐OH groups in the pores of NU‐1000, NU‐1000 can selectively adsorb PEG with larger molecular weights from PEG mixture. This separation method consistently yields with narrower molecular weight distribution across multiple cycles. This is the first application of MOFs in regulating the dispersity (Ð) of polymers in solution, providing a novel approach for separating and purifying mixed molecular weight polymers. [ABSTRACT FROM AUTHOR]

The directional and dynamic hydrogen bonds are of vital importance for both nucleic acids and proteins, but they naturally apply strong multiple hydrogen bonds in pendant groups and weak single hydrogen bond in the backbone. The hierarchy and orthogonality of multiple and single hydrogen bonds in biological systems inspire to elegantly tailor the supramolecular polymeric materials for robust mechanical properties. Herein, this work has fabricated dynamic ultrastrong and tough supramolecular materials through bioinspired rational design of strong multiple hydrogen bonds in pendant groups and weak single hydrogen bond in the backbone. Based on quadruple hydrogen bonds of ureidopyrimidinone and single hydrogen bond of amide, the supramolecular polymer with optimized hierarchical hydrogen bonds possesses high tensile strength and strong toughness of 30.6 MPa and 74.0 MJ m−3, respectively. Meanwhile, the dynamic dissociation and reformation of the hierarchical hydrogen bonds endow the supramolecular polymer with efficient crack resistance, self‐healing, recyclability, and high energy dissipation. Flexible and self‐healing conductors can be prepared by blending the supramolecular polymer with liquid metal in a simple manner. Therefore, this work expects that the plenty of hydrogen bonding pairs in the supramolecular toolkit provide many opportunities to produce robust and tough supramolecular polymeric materials without covalent crosslinking. [ABSTRACT FROM AUTHOR]

AbstractNanomaterials were widely employed to improve the physicochemical properties of various chemicals in enhanced oil recovery (EOR). In the present study, the novel Janus amphiphilic silica nanoparticle (JNS) was successfully prepared, whose structure and property were confirmed via Fourier transform infrared spectroscopy, Zeta potential measurement, transmission electron microscopy, interfacial tension and contact angle measurements. Then the effects of JNS, hydrophilic silica nanoparticles (HLS) and hydrophobic silica nanoparticles (HBS) on the viscosity of the hydrophobic modified HPAM (HOA101) solution were studied. It was found that JNS exhibited a greater ability to enhance the viscosity, temperature resistance and salt resistance of HOA101 solution in comparison to the other two polymer nanofluids. The interaction mechanisms between nanoparticles and HOA101 were proposed, which were verified by the viscoelasticity measurements and control experiments. Core flooding experiments and micromodel flooding tests demonstrated that the JNS/HOA101 dispersion could effectively expand the sweep efficiency to highly increase the oil recovery from 8.4% to 14.3%. [ABSTRACT FROM AUTHOR]

The greater transparency of the polymer obtained by adding a small amount of molecular iodine to the liquid photopolymerizing composition is satisfactorily explained by the formation of a π,σ-type charge transfer (CT) complex of oligocarbonate dimethacrylate with molecular iodine. The CT band at 360 nm absorbs a significant part of the actinic radiation such that the rate of the photolytic decomposition of the photoinitiator in the initial polymerization stage permits release of free volume from the polymer into the liquid part of the photopolymerizing composite. Layer-by-layer photopolymerization occurs at advanced stages due to the thin upper layers exposed to UV irradiation becoming steadily more transparent. [ABSTRACT FROM AUTHOR]

The dynamic modulus of polymer solutions and melts can be expressed as a universal function of reduced frequency when the modulus is scaled by a characteristic value according to the scaling theory of polymer physics. Although the plot of the scaled modulus as a function of the scaled frequency supports the theory, it suffers from considerable scattered distribution of data points around the hypothetical master curve. Compared with the master curve of the time–temperature superposition (TTS) of polymer melts, the master curve of polymer solutions has poor quality. Furthermore, the scale factors of polymer solutions may not show a clear dependency on molecular weight and concentrations. Experimental errors and molecular weight distribution appear to enhance the inaccuracy of the master curve. Therefore, we apply a global optimization for the superposition of the viscoelastic data of polymer solutions with various molecular weights and concentrations. The global optimization resulted in the superposition of data as accurate as that of TTS. Furthermore, the numerically determined shift factors, which were relative scale factors, showed clear dependences on molecular weight and concentrations. We compared our global optimization with previous scaling methodologies. [ABSTRACT FROM AUTHOR]

Context: To determine the miscibility of liquids at high temperatures using the concept of Hildebrand solubility parameter δ , the current practice is to examine the difference in δ between two liquids at room temperature, assuming that δ is not sensitive to temperature. However, such an assumption may not be valid for certain polymer blends and solutions. Therefore, a knowledge of the δ values of the liquids of interest at high temperatures is desirable. The determination of δ at high temperatures, especially for high-molecular-weight polymers, is impossible, as polymers have vapor pressures of zero. To this end, molecular dynamics (MD) simulations provide a practical means for determining δ over a wide range of temperatures. In this work, we study the temperature dependence of δ of five hydrocarbon polymers: polyethylene (PE), isotactic and atactic polypropylene (i-PP and a-PP), polyisobutylene (PIB), and polyisoprene (PI) in five hydrocarbon solvents: n-pentane, n-hexane, n-dodecane, isobutene, and cyclohexane. The polymers are modeled as monodisperse chains with 100 repeat units. The average δ values of PE, i-PP, a-PP, PIB, and PI at 300 K are determined as 18.6, 14.9, 14.6, 14.3, and 16.4 MPa1/2, respectively, in a good agreement with experimental data. The δ values of these polymers at various temperatures are also determined. The temperature dependence of δ is fitted to two linear equations, one above and the other below the polymer's glass transition temperature Tg. The δ values are more sensitive to temperature at T ≥ Tg. The Tg values of the polymers, determined based upon their specific volumes and δ values agree with the experiment qualitatively. The determination of the temperature dependence of δ has a great potential for industrial applications, such as determining miscibility, developing polymeric organogelators as flocculants and oil spill treating agents, and identifying potential solvents and ideal processing temperatures. Methods: The MD simulations are performed using the GROMACS 2022.3 package with optimized potential for liquid simulations-all atom (OPLS-AA) force field parameters. All polymers are built as extended chains using CHARMM-GUI Polymer Builder. [ABSTRACT FROM AUTHOR]

Magnetic (B) fields are an intriguing route for manipulating soft materials. While most research on B field manipulation of diamagnetic polymers has focused on alignment of ordered structures or anisotropic domains, our recent work uncovered a previously unrecognized effect: B fields alter hydration and hydrogen bonding in thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) solutions. Despite the well-known thermoreversible coil-to-globule transition and hydrogel formation upon heating, the impact of magnetic fields on these structural and rheological transitions has been largely unexplored. In this study, we thoroughly examined the temperature-dependent magnetorheology of PNIPAM solutions, varying B field strength, polymer content, and molecular weight. Linear magnetorheology reveals that increasing the B field intensity decreases the dynamic moduli of the resulting physical hydrogel, across polymer concentrations (5–20% wt) and molecular weights (30–108 kDa), by up to an order of magnitude. Conversely, the gelation onset temperature does not change substantially. This weakening effect is more pronounced at longer magnetization times and slower temperature ramp rates. Nonlinear magnetorheology following hydrogel formation reveals a two-step yielding process characteristic of attractive-driven glasses, suggesting that magnetization decreases both the stress and length scales associated with mesoglobule cage breaking. We propose that B fields impact the hydrogel rheology by altering the mesoglobule size and water content. This work uncovers essential understanding of how B fields alter hydrogel formation in PNIPAM solutions, broadening the scope of magnetic field manipulation of diamagnetic polymer solutions. [ABSTRACT FROM AUTHOR]

We study the collective elastic behavior of semiflexible polymer solutions in a nematic liquid-crystalline state using polymer field theory. Our polymer field-theoretic model of semiflexible polymer solutions is extended to include second-order fluctuation corrections to the free energy, permitting the evaluation of the Frank elastic constants based on orientational order fluctuations in the nematic state. Our exact treatment of wormlike chain statistics permits the evaluation of behavior from the nematic state, thus accurately capturing the impact of single-chain behavior on collective elastic response. Results for the Frank elastic constants are presented as a function of aligning field strength and chain length, and we explore the impact of conformation fluctuations and hairpin defects on the twist, splay, and bend moduli. Our results indicate that the twist elastic constant Ktwist is smaller than both bend and splay constants (Kbend and Ksplay, respectively) for the entire range of polymer rigidity. Splay and bend elastic constants exhibit regimes of dominance over the range of chain stiffness, where Ksplay > Kbend for flexible polymers (large-N limit) while the opposite is true for rigid polymers. Theoretical analysis also suggests the splay modulus tracks exactly to that of the end-to-end distance in the transverse direction for semiflexible polymers at intermediate to large-N. These results provide insight into the role of conformation fluctuations and hairpin defects on the collective response of polymer solutions. [ABSTRACT FROM AUTHOR]

We present a simple mean-field theory to describe the polymer-mediated depletion attraction between colloidal particles that accounts for the polymer's chain stiffness. We find that for fixed polymer radius of gyration and volume fraction, the strength of this attraction increases with increasing chain stiffness in both dilute and semidilute concentration regimes. In contrast, the range of attraction monotonically decreases with chain stiffness in the dilute regime, while it attains a maximum in the semidilute regime. The obtained analytical expressions for the depletion interaction were compared with numerical self-consistent field lattice computations and shown to be in quantitative agreement. From the interaction potential between two spheres, we calculated the second osmotic virial coefficient B2, which appears to be a convex function of chain stiffness. A minimum of B2 as a function of chain stiffness was observed both in the numerical self-consistent field computations and the analytical theory. These findings help explain the general observation that semiflexible polymers are more effective depletants than flexible polymers and give insight into the phase behavior of mixtures containing spherical colloids and semiflexible polymers. [ABSTRACT FROM AUTHOR]

The complexity and diversity of polymer topologies, or chain architectures, present substantial challenges in predicting and engineering polymer properties. Although machine learning is increasingly used in polymer science, applications to address architecturally complex polymers are nascent. Here, we use a generative machine learning model based on variational autoencoders and data generated from molecular dynamics simulations to design polymer topologies that exhibit target properties. Following the construction of a dataset featuring 1342 polymers with linear, cyclic, branch, comb, star, or dendritic structures, we employ a multi-task learning framework that effectively reconstructs and classifies polymer topologies while predicting their dilute-solution radii of gyration. This framework enables the generation of polymer topologies with target size, which is subsequently validated through molecular simulation. These capabilities are then exploited to contrast rheological properties of topologically distinct polymers with otherwise similar dilute-solution behavior. This research opens avenues for engineering polymers with more intricate and tailored properties with machine learning. [ABSTRACT FROM AUTHOR]

The application of polymer flooding is currently under investigation to control water cut and recover residual oil from a giant sandstone reservoir in Kazakhstan, where the water cut in most producers exceeds 90%, leaving substantial untouched oil in the porous media. The primary objective of this research is to explore the feasibility of a novel approach that combines the mechanisms of mobility control by polymer injection and the thermal effects, such as oil viscosity reduction, by utilizing hot water to prepare the polymer solution. This innovative hybrid method's impact on parameters like oil recovery, resistance factor, and mobility was measured and analyzed. The research involved an oil displacement study conducted by injecting a hot polymer at a temperature of 85 °C, which is higher than the reservoir temperature. Incremental recovery achieved through hot polymer injection was then compared to the recovery by conventional polymer flooding and the conventional surfactant–polymer-enhanced oil recovery techniques. The governing mechanisms behind recovery, including reductions in oil viscosity, alterations in polymer rheology, and effective mobility control, were systematically studied to comprehend the influence of this proposed approach on sweep efficiency. Given the substantial volume of residual oil within the studied reservoir, the primary objective is to improve the sweep efficiency as much as possible. Conventional polymer flooding demonstrated a moderate incremental oil recovery rate of approximately 48%. However, with the implementation of the new hybrid method, the recovery rate increased to more than 52%, reflecting a 4% improvement. Despite the polymer's lower viscosity during hot polymer flooding, which was observed by the lower pressure drop in contrast to the conventional polymer flooding scenario, the recovery factor was higher. This discrepancy indicates that while polymer viscosity decreases, the activation of other oil displacement mechanisms contributes to higher oil production. Applying hybrid enhanced oil recovery mechanisms presents an opportunity to reduce project costs. For instance, achieving comparable results with lower chemical concentrations is of practical significance. The potential impact of this work on enhancing the profitability of chemically enhanced oil recovery within the sandstone reservoir under study is critical. [ABSTRACT FROM AUTHOR]

The world is rich in ordinary heavy‐oil resources. Exploring the limit of the crude oil viscosity limits can further expand the application of polymer flooding technology in heavy‐oil reservoirs and improve the development efficiency of heavy‐oil reservoirs. On the basis of the polymer flooding that has been implemented in the Bohai offshore oilfield, this study characterized the in situ viscoelasticity of the polymer solution SNF3640C. We compared the polymer flooding and glycerol flooding performance in low‐viscous oil reservoirs (with a viscosity of 6.5 cp) and high‐viscous oil reservoirs (with a viscosity of 65 cp) by conducting microscopic dead‐end experiments and macroscopic core‐flooding experiments, and then analyzing the impact of polymer's viscoelasticity on the oil displacement efficiency of heavy oil. Finally, multiple crude oils with a wide range of viscosity were used to explore the crude oil viscosity limits under which the efficiency of heavy‐oil displacement could be improved through polymer viscoelasticity. The results demonstrate that: (1) the SNF3640C polymer solution can exhibit a certain degree of viscoelasticity in deep formation. At a distance of 140 m from the wellbore in the reservoir, a solution with a concentration of 1500 mg/L can still have a first normal stress difference of 2.5 Pa. Polymers can effectively improve the efficiency of heavy‐oil displacement through elastic action. (2) The viscosity limit that can improve the efficiency of heavy‐oil displacement under current experimental conditions does not exceed 5486 cp. The efficiency of polymer flooding for crude oil has decreased to 31.68%, and the contribution of elastic flooding is only 1.5%. The research method of using viscous glycerol as a comparison to demonstrate the contribution of polymer elasticity to oil displacement effectiveness effectively solves the problem of isolating the contribution by polymer solution's viscosity and elasticity, and clarifies the development direction of polymer flooding for developing heavy crude oil. Enhancing the elastic effect of polymer solution in porous media can increase the viscosity range of polymer flooding heavy oil. [ABSTRACT FROM AUTHOR]

Polymer flooding has proved an effective technique to improve development efficiency in heterogeneous reservoirs. Previously, operators usually employed continuous injection of large polymer slugs. However, problems existed including premature injection profile reversal during development, ineffective circulation of polymer solution in low-permeability zones, and excessive polymer consumption in the late development stage. The paper proposed a combination method, named as polymer-alternating-water (PAW), to solve the issues of traditional polymer flooding. The characteristic of this method is injecting water slugs between polymer slugs during the polymer flooding process. At present, research on the PAW technique is limited, with the operational parameters, oil recovery mechanisms, and applicability under various reservoir conditions remaining unclear. In this work, a numerical polymer flooding model is developed using the commercial CMG-STARS reservoir simulation module to investigate the oil displacement performance of PAW. Numerical simulations are performed to determine the optimal parameters for maximizing oil recovery factor. The results indicated compared with continuous polymer flooding, PAW shows multiple peaks in daily oil production rate, with a significantly decreased decline rate, resulting in a 1.47% increase in recovery factor. Under different reservoir conditions including mean permeability, heterogeneity, and crude oil viscosity, PAW can achieve further improvements on the basis of continuous polymer flooding. Polymer adsorption and injection concentration significantly impact the recovery factor, requiring further optimization for field applications. In this study, better polymer flooding performance was achieved when the number of alternating cycles of PAW was 2, and the injected alternating water slug volume was 50%. This study contributes to a deeper understanding of the key mechanisms and parameters in PAW enhanced oil recovery process, thereby providing guidance for the further optimization and field application of this technique. [ABSTRACT FROM AUTHOR]

The thermo-responsive behavior of Poly(N-isopropylacrylamide) makes it an ideal candidate to easily embed cells and allows the polymer mixture to be injected. However, P(NiPAAm) hydrogels possess minor mechanical properties. To increase the mechanical properties, a covalent bond is introduced into the P(NIPAAm) network through a biocompatible thiol-ene click-reaction by mixing two polymer solutions. Co-polymers with variable thiol or acrylate groups to thermo-responsive co-monomer ratios, ranging from 1% to 10%, were synthesized. Precise control of the crosslink density allowed customization of the hydrogel's mechanical properties to match different tissue stiffness levels. Increasing the temperature of the hydrogel above its transition temperature of 31 °C induced the formation of additional physical interactions. These additional interactions both further increased the stiffness of the material and impacted its relaxation behavior. The developed optimized hydrogels reach stiffnesses more than ten times higher compared to the state of the art using similar polymers. Furthermore, when adding cells to the precursor polymer solutions, homogeneous thermo-responsive hydrogels with good cell viability were created upon mixing. In future work, the influence of the mechanical micro-environment on the cell's behavior can be studied in vitro in a continuous manner by changing the incubation temperature. [ABSTRACT FROM AUTHOR]

On account of some special advantages of interpenetrating polymer networks (IPNs), the preparation of IPNs with excellent properties may be a promising way to strengthen the polyurethanes (PUs) and toughen the glycidyl azide polymer (GAP) based polytriazoles (PTAs). This work provides the effect of composition and number average molecular weight (Mn) of GAP on the mechanical properties and morphology of full‐IPNs. A series of IPNs based on the crosslinked Ace‐terminated GAP (Ace‐GAP) as polytriazole phase and crosslinked hydroxy‐terminated liquid fluorinated polymer (HTLF‐1500) as polyurethane phase (namely, GAP‐HTLF‐X full‐IPNs) were successfully fabricated via in situ polymerization without any catalysts at 80°C by azide–alkynyl click chemistry and hydroxyl‐isocyanate urethane reaction. These IPNs were characterized using attenuated total reflectance/Fourier‐transform infrared spectroscopy (ATR/FTIR), uniaxial tensile testing, swelling measurement, and scanning electron microscopy (SEM). The tensile strength of GAP‐HTLF full‐IPNs gradually increased by increasing the weight ratio of Ace‐GAP, but the breaking elongation dramatically decreased compared with elongation at break of HTLF polyurethane. In addition, a small Mn of GAP is beneficial in enhancing the tensile strength, elongation at break and toughness of the IPNs. However, a small Mn of GAP corresponds to increased difficulty of preparing GAP‐HTLF full‐IPNs. GAP1k‐HTLF full‐IPN was not successfully prepared. When the Mn of GAP was 2000 g/mol, the GAP2k‐HTLF‐80 full‐IPN exhibited prominent mechanical performance with a tensile strength of 83.1 MPa, elongation at break of 28.5% and fracture energy of 99.1 kJ/m3. Swelling measurement showed that when the weight ratio of GAP with larger Mn (5, 3, and 2 k) increased to more than 70%, the molecular interpenetration existed in the IPNs, demonstrating the presence of additional physical crosslinks and entanglement for full‐IPNs. SEM studies revealed that highly formed interpenetration and few microphase separations can be observed on the fracture surface of the IPNs with optimal mechanical properties. Combined with the results of mechanical properties, swelling measurement, and SEM studies, the degree of molecular interpenetration and microphase separation were beneficial to improve the mechanical properties of elastomers. This work can provide a certain guiding significance for the preparation of IPN with excellent properties. [ABSTRACT FROM AUTHOR]

This study introduces an efficient strategy for synthesizing polyhydroxyurethane-based multicomponent hydrogels with enhanced rheological properties. In a single-step process, 3D materials composed of Polymer 1 (PHU) and Polymer 2 (PVA or gelatin) were produced. Polymer 1, a crosslinked polyhydroxyurethane (PHU), grew within a colloidal solution of Polymer 2, forming an interconnected network. The synthesis of Polymer 1 utilized a Non-Isocyanate Polyurethane (NIPU) methodology based on the aminolysis of bis(cyclic carbonate) (bisCC) monomers derived from 1-thioglycerol and 1,2-dithioglycerol (monomers A and E, respectively). This method, applied for the first time in Semi-Interpenetrating Network (SIPN) formation, demonstrated exceptional orthogonality since the functional groups in Polymer 2 do not interfere with Polymer 1 formation. Optimizing PHU formation involved a 20-trial methodology, identifying influential variables such as polymer concentration, temperature, solvent (an aprotic and a protic solvent), and the organo-catalyst used [a thiourea derivative (TU) and 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU)]. The highest molecular weights were achieved under near-bulk polymerization conditions using TU-protic and DBU-aprotic as catalyst–solvent combinations. Monomer E-based PHU exhibited higher M w ¯ than monomer A-based PHU (34.1 kDa and 16.4 kDa, respectively). Applying the enhanced methodology to prepare 10 multicomponent hydrogels using PVA or gelatin as the polymer scaffold revealed superior rheological properties in PVA-based hydrogels, exhibiting solid-like gel behavior. Incorporating monomer E enhanced mechanical properties and elasticity (with loss tangent values of 0.09 and 0.14). SEM images unveiled distinct microstructures, including a sponge-like pattern in certain PVA-based hydrogels when monomer A was chosen, indicating the formation of highly superporous interpenetrated materials. In summary, this innovative approach presents a versatile methodology for obtaining advanced hydrogel-based systems with potential applications in various biomedical fields. [ABSTRACT FROM AUTHOR]

A new method of determining the dimensions and shapes of polymer molecules in solutions is proposed and verified in experiments. The method is based on the measurements of the relaxation of the transverse magnetization intensity of nuclei. It is established that the decaying signal of the spin echo from elongated molecules contains two terms exponentially decaying with time, which correspond to two diffusion coefficients differing by a factor of about two. The signal from molecules with a near-spherical shape contain only one exponent. [ABSTRACT FROM AUTHOR]

New regularities have been discovered in the synthesis of polymer ionic liquids and ionene-type ionic liquids based on polyionenes derived from tetrahydro-1,4-oxazine. The methods for regulating the molecular weight of the synthesized polymers have been improved by varying the nature and composition of the solvent, as well as the concentration of the starting monomers. These improvements have resulted in the creation of new and promising materials. For the first time, we investigated the effects of temperature, solvent type and composition, chemical structure, and concentration of polyionenes derived from tetrahydro-1,4-oxazine on their behavior in water and water-ethanol solutions, as well as the shape of macromolecules in different solvents. Newly synthesized polymeric ionic liquids and ionene ionic liquids with an ionic conductivity of ≈10-2-10-5 S·cm-1 and a glass transition temperature range of -150°C÷-15°C exhibit five to six orders of magnitude higher ionic conductivity compared to known analogues. [ABSTRACT FROM AUTHOR]

Bottlebrush polymers are a class of highly branched macromolecules that show promise for applications such as self-assembled photonic materials and tunable elastomers. However, computational studies of bottlebrush polymer solutions and melts remain challenging due to the high computational cost involved in explicitly accounting for the presence of side chains. Here, we consider a coarse-grained molecular model of bottlebrush polymers where the side chains are modeled implicitly, with the aim of expediting simulations by accessing longer length and time scales. The key ingredients of this model are the size of a coarse-grained segment and a suitably coarse-grained interaction potential between the non-bonded segments. Prior studies have not focused on developing explicit forms of such potentials, instead, relying on scaling arguments to model non-bonded interactions. Here, we show how to systematically calculate an interaction potential between the coarse-grained segments of bottlebrush from finer grained explicit side chain models using Monte Carlo and Brownian dynamics and then incorporate it into an implicit side chain model. We compare the predictions from our coarse-grained implicit side chain model with those obtained from models with explicit side chains in terms of the potential of mean force, the osmotic second virial coefficient, and the interpenetration function, highlighting the range of applicability and limitations of the coarse-grained representation. Although presented in the context of homopolymer bottlebrushes in athermal solvents, our proposed method can be extended to other solvent conditions as well as to different monomer chemistries. We expect that our implicit side chain model will prove useful for accelerating large-scale simulations of bottlebrush solutions and assembly. [ABSTRACT FROM AUTHOR]

Poly(N-acryloylglycinamide) (PNAGA) exhibits an upper critical solution temperature (UCST) behaviour in aqueous solutions, and unlike typical polymers, dissolution is more sensitive to temperature and solutions may exhibit an extraordinary rheological behavior. Homopolymers of NAGA with different molecular weights were synthesized, the rheological behavior of the polymer solutions was investigated, and the scaling relationships of the dilute solutions of polymers were analyzed. The results indicated that PNAGA is a thermoviscosifying polymer in aqueous solutions. Besides, the thermoviscosifying behaviour was intense above 50 °C, as well as at lower concentrations, and the viscosity rising up to 27.61 times at concentration of 0.1%. The lower molecular weight polymers prepared showed more thermoviscosification. The polymer solutions are thermoviscosified over the range of tested shear rates, exhibiting increased shear resistance. Light scattering tests showed that the molecular size increased with increasing temperature at the same concentration, combined with the scale relationship that the solution contact concentration decreased with increasing temperature, indicating polymer coil expansion with increasing temperature. [ABSTRACT FROM AUTHOR]

This document is an editorial that highlights the significance of polymer processing techniques in the production of polymer components. It emphasizes the importance of using advanced modeling codes and experimental work to optimize polymer processing. The editorial presents several cutting-edge papers that contribute to the numerical, theoretical, and experimental knowledge of polymer physics. These papers cover a range of topics, including numerical methods for fluid flow simulations, non-Newtonian fluid mixing, molecular dynamics simulations of DNA polymers, theoretical models for polystyrene behavior, analytical solutions for polymer fluid flows, experimental investigations on drag-reducing polymers, characterization of thin films for energy storage, fabrication of cellulose nanocrystal-based materials, dynamic crushing performance of expanded polyethylene, and the influence of polycarboxylate ether superplasticizers on concrete behavior. The editorial concludes by stating that it serves as a valuable reference for researchers interested in staying updated on cutting-edge technologies in polymer physics. [Extracted from the article]

In this work, indoor physical simulation experiments were used to examine the effects of shear, thermal, chemical, and microbial degradation on the properties of the hydrophobic associative polymer AP‐P4. It was discovered that the viscosity of the polymer solution generally decreased as the shear time was extended. The larger the shear strength, the lower the solution viscosity. Fitting of the nonlinear equation of solution viscosity with shear time, η = 12,988 t−1.08. When thermal degradation started, the solution viscosity first started to rise, however, this phase was just a short one. The viscosity of the solution gradually started to decrease as the thermal degradation period grew. In addition, the trends of properties like hydrokinetic radius, hydrophobic connectivity, and hydrolysis essentially followed the same patterns as those of solution viscosity. At the beginning of the degradation process, the viscosity retention of the polymer solution without oxygen is significantly higher than that of the aerobic environment. However, the difference between the two becomes smaller as the degradation time increases. In addition, the AP‐P4 had good temperature resistance and aging resistance capabilities when iron ions were present. Finally, it was discovered that AP‐P4 had a strong antibacterial effect, which decreased the viscosity brought on by microbial action. [ABSTRACT FROM AUTHOR]

Polybenzimidazoles (PBIs) are recognized for their remarkable thermal stability due to their unique molecular structure, which is characterized by aromaticity and rigidity. Despite their remarkable thermal attributes, their tensile properties limit their application. To improve the mechanical performance of PBIs, we made a vital modification to their molecular backbone to improve their structural flexibility. Non-π-conjugated components were introduced into PBIs by grafting meta-polyamide (MA) and para-polyamide (PA) onto PBI backbones to form the copolymers PBI-co-MA and PBI-co-PA. The results indicated that the cooperation between MA and PA significantly enhanced mechanical strain and overall toughness. Furthermore, the appropriate incorporation of aromatic polyamide components (20 mol% for MA and 15% for PA) improved thermal degradation temperatures by more than 30 °C. By investigating the copolymerization of PBIs with MA and PA, we unraveled the intricate relationships between composition, molecular structure, and material performance. These findings advance copolymer design strategies and deepen the understanding of polymer materials, offering tailored solutions that address thermal and mechanical demands across applications. [ABSTRACT FROM AUTHOR]

For the first time, copolymers of polyphenylene sulfone (PPSU) with cardo fragments of phenolphthalein (PP) were synthesized to develop highly permeable flat-sheet ultrafiltration membranes. By introducing cardo fragments into the polymer chain, we achieved a mechanical strength 1.3 times higher than the strength of commercial PPSU. It is shown that the introduction of the cardo monomer significantly increases the solubility of the polymer in aprotic solvents. The highest solubility is observed at the concentration of PP 50 mol.%. It is found that reduced viscosity of cardo polymer solutions leads to an increase in the coagulation rate. The permeance of asymmetric ultrafiltration membranes increases with PP concentration from 17.5 L/(m2·h·bar) (10 mol.% PP) to 85.2 L/(m2·h·bar) (90 mol.% PP). These data are in agreement with the results of a study of the coagulation rate of polymer solutions. Thus, for ultrafiltration membranes with 1.5–8 times higher permeance in comparison with PPSU due to the introduction of cardo fragments in the polymer chain, possessing high rejection of the model dye Blue Dextran (MW = 70,000 g/mol), more than 99.2%, as well as high strength characteristics, were achieved. [ABSTRACT FROM AUTHOR]

We investigate the well-posedness of a coupled Navier-Stokes-Fbkker-Planck system with a time-fractional derivative. Such systems arise in the kinetic theory of dilute solutions of polymeric liquids, where the motion of noninteracting polymer chains in a Newtonian solvent is modeled by a stochastic process exhibiting power-law waiting time in order to capture Subdiflfusive processes associated with non-Fickian diffusion. We outline the derivation of the model from a subordinated Langevin equation. The elastic properties of the polymer molecules immersed in the solvent are modeled by a finitely extensible nonlinear elastic dumbbell model, and the drag term in the Fokker-Planck equation is assumed to be Corotational. We prove the global-in-time existence of large-data weak solutions to this time-fractional model of order a ∈ (∣, 1) and derive an energy inequality satisfied by weak solutions. [ABSTRACT FROM AUTHOR]

Solutions of flexible, entangled polymer chains dissolved in athermal solvents have been widely studied; however, the influence of the local swelling effects on the overall dynamics of such systems remains incompletely understood. In this study, we performed coarse-grained simulations to compute the concentration dependence of plateau modulus of such systems. Initially, we examined the concentration dependence of entanglement length, denoted as Ne, through simulations. Our findings revealed a concentration scaling relationship for Ne, demonstrating N e = A Φ − 5 / 4 + B , where A and B are chain length independent constants, and Φ is polymer concentration. To account for the local swelling effects, we employed the concept of blobs to represent the chains confined in athermal solvents. Each blob was characterized by a diameter ξ, a number of connected beads g, and a volume Ω b ∼ ξ 3 . Our simulations showed that the blob diameter followed the excluded volume relationship, with ξ ∼ g 3 / 5 . By combining the local swelling effect and the non-zero constant B, we derived a concentration scaling relationship for the plateau modulus G of solutions of flexible polymer chains in athermal solvents: G ∼ Φ (N e / g) Ω b ∼ Φ 2.30 . This scaling exponent aligns with experimental observations ranging from dilute to highly concentrated systems, as well as our simulations, where values of 2.0–2.3 were observed. [ABSTRACT FROM AUTHOR]