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Abstract A novel conjugated rod–coil diblock copolymer poly(3-hexylthiophene)-block-poly(furfuryl methacrylate) (P3HT-b-PFMA) has been successfully synthesized for the first time using photoinduced organocatalyzed atom transfer radical polymerization (O-ATRP). This process utilized an organic photoredox catalyst of N-aryl phenoxazine, namely 10-(Perylene-3-yl-10H-Phenoxazine, under 365 nm UV irradiation. The diblock copolymer P3HT-b-PFMA was produced efficiently in a controlled manner, resulting in designed average molecular weights and a narrow polydispersity index. Notably, the furfurylmethacrylate (FMA) monomer derived from biomass-based furfuryl compounds was applied for this controlled polymerization, leading to the formation of conjugated diblock copolymers. The synthesized P3HT-b-PFMA was characterized through 1H-NMR, FT-IR, and GPC methods. Furthermore, the optical and hydrophilic-hydrophobic properties of P3HT-b-PFMA were also evaluated through UV-Vis spectroscopy and contact angle measurements.

Methoxy poly(ethylene glycol)-block-poly(L-lactide) (MPEG-b-PLLA) has a wide range of applications in pharmaceuticals and biology, and its structure and morphology have been thoroughly studied. In the experiment, we synthesized MPEG-b-PLLA with different block lengths using the principle of ring-opening polymerization by controlling the amount of lactic acid added. The thermodynamic properties of copolymers and the crystallization properties of blends were studied separately. The crystallization kinetics of PDLA/MPEG-b-PLA and PLLA/MPEG-b-PLA composite films were studied using differential scanning calorimetry (DSC). The results indicate that the crystallization kinetics of composite films are closely related to the amount of block addition. The crystallinity of the sample first increases and then decreases with an increase in MPEG-b-PLLA content. These results were also confirmed in polarized optical microscope (POM) and wide-angle X-ray diffraction (WAXD) tests. When 3% MPEG-b-PLLA was added to the PDLA matrix, the blend exhibited the strongest crystallization performance. [ABSTRACT FROM AUTHOR]

The self-assembly behaviour of a diblock copolymer-diblock copolymer mixture under an oscillating shear field is investigated via cell dynamics simulation. The results indicate that the macrophase separation of the composite system is accompanied by the corresponding microphase separation induced by the oscillating shear field. With an increase in the shear frequency, the AB phase changes from a tilted layered structure to a parallel layered structure, and finally to a vertical layered structure. The CD phase transforms from the initial concentric ring into a parallel layer in the ring and then into a parallel layered structure; thus, the system finally forms a layered structure of the AB phase (vertical layer) and CD phase (parallel layer) perpendicular to each other. To verify the phase transition, the dynamic evolution of the domain size at different shear frequencies is analysed. The ordered phase transition with an increase in the oscillating shear field varies when the initial composition ratio of the system is changed. This conclusion provides a valuable guidance for the formation and transformation of ordered structures in experiments. [ABSTRACT FROM AUTHOR]

The self-assembly behaviour of a diblock copolymer-diblock copolymer mixture under an oscillating shear field is investigated via cell dynamics simulation. The results indicate that the macrophase separation of the composite system is accompanied by the corresponding microphase separation induced by the oscillating shear field. With an increase in the shear frequency, the AB phase changes from a tilted layered structure to a parallel layered structure, and finally to a vertical layered structure. The CD phase transforms from the initial concentric ring into a parallel layer in the ring and then into a parallel layered structure; thus, the system finally forms a layered structure of the AB phase (vertical layer) and CD phase (parallel layer) perpendicular to each other. To verify the phase transition, the dynamic evolution of the domain size at different shear frequencies is analysed. The ordered phase transition with an increase in the oscillating shear field varies when the initial composition ratio of the system is changed. This conclusion provides a valuable guidance for the formation and transformation of ordered structures in experiments.

A fingerprint is the unique, complex pattern of ridges and valleys on the surface of an individual's fingertip. Fingerprinting is one of the most popular and widely used biometric authentication methods for personal identification because of its reliability, acceptability, high level of security, and low cost. When using fingerprints as a biometric, restoring poor-quality or damaged fingerprints is an essential process for accurate verification. In this study, we present a semi-automatic fingerprint image restoration method using a partial differential equation to repair damaged fingerprint images. The proposed algorithm is based on the Cahn-Hilliard (CH) equation with a source term, which was developed for simulating pattern formation during the phase separation of diblock copolymers in chemical engineering applications. In previous work, in order to find an optimal model and numerical parameter values in the governing equation, we had to make several trial and error preliminary attempts. To overcome these problems, the proposed novel algorithm minimizes user input and automatically computes the necessary model and numerical parameter values of the governing equation. Computational simulations on various damaged fingerprint samples are presented to demonstrate the superior performance of the proposed method.

The self-assembly behavior of AB diblock copolymer confined in staggering alternately adsorbed thin films is studied using the self-consistent field theory (SCFT) and dissipative particle dynamics (DPD), focusing on the emergence and stability of the undulated lamella (UL) phase. Phase diagrams for the volume fraction of blocks, period of the adsorbed pattern and thickness of the confinement are constructed. Our results indicate that the UL phase can be stable in the case with a large period of adsorbed pattern, and is more favorable in the asymmetrical diblock copolymer with volume fraction around f = 0.40, which becomes cylindrical phases (C) with too small f and transforms into tilted lamellae (TL) on the contrary. Furthermore, the number of layers in the UL phases can be regulated by adjusting the period of the adsorbed pattern and the confinement degree of the thin film. In addition, the formation of the UL is verified by DPD simulations. The study demonstrates that the specially confined diblock copolymers provide an efficient route to regulate the stability of the complex UL phases.

This study proposes a hydrophobic and hydrophilic aliphatic diblock copolymer wherein the hydrophobic block contains glycidyl methacrylate (GMA) units that are distanced by poly(acrylonitrile) (PAN) segments to fabricate a proton exchange membrane (PEM). This diblock copolymer also known as ionomer due to the hydrophilic block comprising 3-sulfopropyl methacrylate potassium salt (SPM) block. The diblock copolymer was synthesized in the one-pot atom transfer radical polymerization (ATRP) synthesis. Subsequently, the membrane was fabricated by means of solution casting in which an organic diamine, e.g., ethylene diamine (EDA), was introduced to crosslink the diblock copolymer chains via the addition of amine to the epoxide group of GMA. As a result, the PEM attained possesses dual continuous phases, in which the hydrophobic domains are either agglomerated or bridged by the EDA-derived crosslinks, whereas the hydrophilic domains constitute the primary proton conducting channels. The in-situ crosslinking hydrophobic block by using a hydrophilic cross-linker represents the merit aspect since it leads to both improved proton conductivity and dimensional stability in alcohol fuel. To characterize the above properties, Nafion® 117 and random copolymer of P(AN-co-GMA-co-SPM) were used as control samples. The PEM with the optimized composition demonstrates slightly better fuel cell performance than Nafion 117. Lastly, this diblock ionomer is nonfluorinated and hence favors lowering down both material and environmental costs.

Porphyrin compound-based photochemical molecules and biomaterials have been synthesized for photosensitivity and bioimaging experiments. However, most porphyrin photosensitizers have limited application in biological environments owing to severe aggregation in aqueous solutions. In the present study, we prepared amphipathic and photosensitive copolymers using zinc porphyrin via consecutive atom transfer-free radical polymerizations (ATRPs) comprising photoresponsive and thermosensitive chain segments. Furthermore, we evaluated the photocatalytic activity of the copolymer for methylene blue (MB) in water.Methods: First, we synthesized a photoresponsive ain segment of poly (6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate) (ZnPor-PAzo); then, ZnPor-PAzo was used as a macroinitiator and was polymerized with N-isopropylacrylamide (NIPAM) via ATRPs to obtain a novel photochemical and thermoresponsive diblock biomaterial with end-functionalized zinc porphyrin [(ZnPor-PAzo)–PNIPAMs].Results: The polydispersity index (Mw/Mn) of (ZnPor-PAzo)–PNIPAMs was 1.19–1.32. Furthermore, its photoresponsive and thermosensitive characteristics were comprehensively studied.Discussion: The end-functionalized diblock copolymer (ZnPor-PAzo)–PNIPAM exhibits obvious fluorescence and efficient photocatalytic activity for aqueous MB under visible light.

An efficient modified leapfrog time-marching scheme for the diblock copolymer model is investigated in this paper. The proposed scheme offers three main advantages. Firstly, it is linear in time, requiring only a linear algebra system to be solved at each time-marching step. This leads to a significant reduction in computational cost compared to other methods. Secondly, the scheme ensures unconditional energy stability, allowing for a large time step to be used without compromising solution stability. Thirdly, the existence and uniqueness of the numerical solution at each time step is rigorously proven, ensuring the reliability and accuracy of the method. A numerical example is also included to demonstrate and validate the proposed algorithm, showing its accuracy and efficiency in practical applications. [ABSTRACT FROM AUTHOR]

Hierarchical nanomaterials have received increasing interest for many applications. Here, we report a facile programmable strategy based on an embedded segmental crystallinity design to prepare unprecedented supramolecular planar nanobrush-like structures composed of two distinct molecular packing motifs, by the self-assembly of one particular diblock copolymer poly(ethylene glycol)-block-poly(N-octylglycine) in a one-pot preparation. We demonstrate that the superstructures result from the temperature-controlled hierarchical self-assembly of preformed spherical micelles by optimizing the crystallization-solvophobicity balance. Particularly remarkable is that these micelles first assemble into linear arrays at elevated temperatures, which, upon cooling, subsequently template further lateral, crystallization-driven assembly in a living manner. Addition of the diblock copolymer chains to the growing nanostructure occurs via a loosely organized micellar intermediate state, which undergoes an unfolding transition to the final crystalline state in the nanobrush. This assembly mechanism is distinct from previous crystallization-driven approaches which occur via unimer addition, and is more akin to protein crystallization. Interestingly, nanobrush formation is conserved over a variety of preparation pathways. The precise control ability over the superstructure, combined with the excellent biocompatibility of polypeptoids, offers great potential for nanomaterials inaccessible previously for a broad range of advanced applications.

We investigate pattern formation in a two-dimensional manifold using the Otha-Kawasaki model for micro-phase separation of diblock copolymers. In this model, the total energy includes a short-range and a long-range term. The short-range term is a Landau-type free energy that is common in phase separation problems and favors large domains with minimum perimeter. The inhibitory long-range interaction term is the Otha-Kawasaki functional derived from the theory of diblock copolymers and favors small domains. The balance of these terms leads to equilibrium states that exhibit a variety of patterns, including disk-like droplets, droplet assemblies, elongated droplets, dog-bone shaped droplets, stripes, annular rings, wriggled stripes and combinations thereof. For problems where analytical results are known, we compare our numerical results and find good agreement. Where analytical results are not available, our numerical methods allow us to explore the solution space revealing new stable patterns. We focus on the triaxial ellipsoid, but our methods are general and can be applied to higher genus surfaces and surfaces with boundaries.

Phase behaviors of molten A-b-B diblock copolymers with disparity in self dispersion interactions are revisited here. A free energy functional is obtained for the corresponding Gaussian copolymers under the influence of effective interactions originating in the localized excess equation of state. The Landau free energy expansion is then formulated as a series in powers of A and B density fluctuations up to 4th order. An alternative and equivalent Landau energy is also provided through the transformation of the order parameters to the fluctuations in block density difference and free volume fraction. The effective Flory χ is elicited from its quadratic term as the sum of the conventional enthalpic χ H and the entropic χ S that is related to energetic asymmetry mediated by copolymer bulk modulus. It is shown that the cubic term is balanced with Gaussian cubic vertex coefficients in corporation with energetics to yield a critical point at a composition rich in a component with stronger self interactions. The full phase diagrams with classical mesophases are given for the copolymers exhibiting ordering upon cooling and also for others revealing ordering reversely upon heating. These contrasting temperature responses, along with the skewness of phase boundaries, are discussed in relation to χ H and χ S . The pressure dependence of their ordering transitions is either barotropic or baroplastic; or anomalously exhibits anomalously both at different stages. These actions are all explained by the opposite responses of χ H and χ S to pressure. [ABSTRACT FROM AUTHOR]

An efficient modified leapfrog time-marching scheme for the diblock copolymer model is investigated in this paper. The proposed scheme offers three main advantages. Firstly, it is linear in time, requiring only a linear algebra system to be solved at each time-marching step. This leads to a significant reduction in computational cost compared to other methods. Secondly, the scheme ensures unconditional energy stability, allowing for a large time step to be used without compromising solution stability. Thirdly, the existence and uniqueness of the numerical solution at each time step is rigorously proven, ensuring the reliability and accuracy of the method. A numerical example is also included to demonstrate and validate the proposed algorithm, showing its accuracy and efficiency in practical applications.

We investigate pattern formation in a two-dimensional manifold using the Otha-Kawasaki model for micro-phase separation of diblock copolymers. In this model, the total energy includes a short-range and a long-range term. The short-range term is a Landau-type free energy that is common in phase separation problems and favors large domains with minimum perimeter. The inhibitory long-range interaction term is the Otha-Kawasaki functional derived from the theory of diblock copolymers and favors small domains. The balance of these terms leads to equilibrium states that exhibit a variety of patterns, including disk-like droplets, droplet assemblies, elongated droplets, dog-bone shaped droplets, stripes, annular rings, wriggled stripes and combinations thereof. For problems where analytical results are known, we compare our numerical results and find good agreement. Where analytical results are not available, our numerical methods allow us to explore the solution space revealing new stable patterns. We focus on the triaxial ellipsoid, but our methods are general and can be applied to higher genus surfaces and surfaces with boundaries. [ABSTRACT FROM AUTHOR]

Base-stable amphiphilic diblock copolymers with a polydiallyl dimethyl ammonium hydroxide block were synthesized and characterized to quantify hydroxide-ion transport in the hydrated state; polystyrene was the hydrophobic block. The challenge of synthesizing a copolymer comprising blocks with very different solubility behaviors was addressed by a combination of reversible addition fragmentation chain transfer polymerization and ion metathesis. Both monomers used in the polymerization are commercially available on industrial scales. Hydroxide-ion conductivities of 0.8 mS/cm were achieved in hot-pressed membranes immersed in water at room temperature despite relatively low water uptake (4.2 water molecules per hydroxide ion). The stability of the polydimethyl ammonium hydroxide chains was investigated in 2 M NaOD at 60 °C. 1H NMR spectroscopy studies showed no detectable degradation after 2000 hours. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2243–2248.

[Display omitted] Chemically or physically distinct patches can be induced on the micelles of amphiphilic block copolymers, which facilitate directional binding for the creation of hierarchical structures. Hence, control over the direction of patches on the micelles is a crucial factor to attain the directionality on the interactions between the micelles, particularly for generating colloidal molecules mimicking the symmetry of molecular structures. We hypothesized that direction and combination of the patches could be controlled by physical confinement of the micelles. We first confined spherical micelles of diblock copolymers in topographic templates fabricated from nanopatterns of block copolymers by adjusting the coating conditions. Then, patch formation was conducted on the confined micelles by exposing them with a core-favorable solvent. Microscopic techniques of SEM, TEM, and AFM were employed to investigate directions of patches and structures of combined micelles in the template. The orientation of the patches on the micelles was guided by the physical confinement of the micelles in linear trenches. In addition, by confining the micelles in a circular hole, we obtained a specific polygon arrangement of the micelles depending on the number of micelles in the hole, which enabled the formation of cyclic colloidal molecules consisting of micelles. [ABSTRACT FROM AUTHOR]

In our approach, using Delsa™ Nano submicron particle size dynamic light scattering analyzer, atomic force microscope, scanning electron microscope, and thermo-gravimetric analyzer, we investigated the self-assembly behavior of block copolymer polystyrene polybutadiene (PS-b-PB) in selective solvent, 2-butanone, as well as the effect of irradiation crosslinking that resulted in the immobilization of micelles. Since the selective solvent, 2-butanone, is the soluble solvent of PS segment and insoluble solvent of polybutadiene (Pb) segment, under suitable conditions, PS-b-PB could form monodisperse "core-shell" nano-micelles microstructure. The experimental results showed that under suitable conditions, PS-b-PB could form monodisperse nano-micelles with different core-shell components in selective solvent, and the size of micelles could be adjusted by controlling the mass fraction of PS-b-PB in the solvent. The micelle solution of 2-butanone/PS-b-PB block polymer system was further irradiated by γ-ray irradiation without oxygen, and the results showed that the micelles had a certain improvement in the micro-morphology and thermodynamic stability. The reason is that the crosslinking reaction of PB chain in the micelles induced by γ-ray irradiation is immobilized, and the cured micelles are no longer affected by ultrasonic vibration, solvent dilution, and volatilization. This study provided a new approach and method for the preparation of polymer nano-micelles.

[Display omitted] Patchy micelles of diblock copolymers can be polymerized into a linear supracolloidal chain. We measure the persistence and contour lengths of supracolloidal chains coated on a solid substrate to evaluate their flexibility. Based on the analysis, the chain is semi-flexible, and the conformation is suitably explained by the worm-like chain model. In addition, utilizing a spin-coating technique with the semi-flexible nature of the chains, we produce a self-supporting film of supracolloidal chains having nanoscale pores essentially from colloidal constituents that tend to form dense packing if there is no prior organization of them into a semi-flexible chain. [ABSTRACT FROM AUTHOR]

Propofol is known as one of the most potential anesthetics which suffer from limited duration of anesthesia water insolubility. Therefore, in the present study, a formulation of propofol- carboxylic acid-poly [ethylene glycol (COO-PEG)]-b-poly[ D,L lactide (PDLA)]-nanomicelle was developed and its characterization was done by transmission electron microscopy (TEM) and dynamic light scattering analysis (DLS) studies. Afterwards, drug release assay was carried out to determine the efficacy of COO-PEG-PLDA nanomicelle in drug delivery systems. Cytotoxic, hemolytic, pharmacokinetic, and permeation assays were also followed by anesthetic efficacy of propofol- COO-PEG-PLDA nanomicelle in the rat hind paw model. The results indicated that the diameter, hydrodynamic radius and zeta potential of fabricated drug-loaded nanomicelles were 30 nm, 73.24 nm and –23.59 mV, respectively and the nanomicelles were stable for a period of 50 min. Also, COO-PEG-PLDA nanomicelle showed a sustained propofol release at physiological pH. Moreover, it was indicated that COO-PEG-PLDA nanomicelle reduced the cytotoxic and hemolytic effects of propofol and increased the steady-state flux (Jss) by 6.64 times (***P

Hierarchical nanomaterials have received increasing interest for many applications. Here, we report a facile programmable strategy based on an embedded segmental crystallinity design to prepare unprecedented supramolecular planar nanobrush-like structures composed of two distinct molecular packing motifs, by the self-assembly of one particular diblock copolymer poly(ethylene glycol)-block-poly(N-octylglycine) in a one-pot preparation. We demonstrate that the superstructures result from the temperature-controlled hierarchical self-assembly of preformed spherical micelles by optimizing the crystallization-solvophobicity balance. Particularly remarkable is that these micelles first assemble into linear arrays at elevated temperatures, which, upon cooling, subsequently template further lateral, crystallization-driven assembly in a living manner. Addition of the diblock copolymer chains to the growing nanostructure occurs via a loosely organized micellar intermediate state, which undergoes an unfolding transition to the final crystalline state in the nanobrush. This assembly mechanism is distinct from previous crystallization-driven approaches which occur via unimer addition, and is more akin to protein crystallization. Interestingly, nanobrush formation is conserved over a variety of preparation pathways. The precise control ability over the superstructure, combined with the excellent biocompatibility of polypeptoids, offers great potential for nanomaterials inaccessible previously for a broad range of advanced applications. [ABSTRACT FROM AUTHOR]

In this paper, a series of well-defined polyethylene-b-polytetrafluoroethylene diblock copolymers (PE–b– PTFEs) were prepared by a coupling reaction of hydroxyl-terminated polyethylene (PE–OH) and isocyanateterminated 1H,1H-perfluoro-1-tetradecanol (PFDO–NCO). PE–OH was prepared by the coordination chain transfer polymerization using 2,6-bis[1-(2,6-diisopropylphenyl)imino ethyl] pyridine iron (II) dichloride /dry ethylaluminoxane/ZnEt2 as catalyst and subsequent in situ oxidation with oxygen. PFDO–NCO was synthesized through the condensation reaction of 1H,1H- perfluoro-1-tetradecanol (PFDO) with isophoronediisocyanate (IPDI). Subsequently, the thermal characterization and the application of these diblock copolymers were investigated. The relationship between the molecular structure and the properties was disclosed. The results indicated that the diblock copolymers were effective surface modification agents for linear low density polyethylene (LLDPE). After that the PE–b–PTFE being spin-coated onto the surface of LLDPE film, the film was dramatically turned into a superhydrophobic film with a water contact angle as high as 151.4º. This kind of film is potential to be used as selfcleaning, anti-icing and anticorrosion material.

The expression and integration of membrane proteins into vesicle membranes is a critical step in the design of cell-mimetic biosensors, bioreactors, and artificial cells. While membrane proteins have been integrated into a variety of nonnatural membranes, the effects of the chemical and physical properties of these vesicle membranes on protein behavior remain largely unknown. Nonnatural amphiphiles, such as diblock copolymers, provide an interface that can be synthetically controlled to better investigate this relationship. Here, we focus on the initial step in a membrane protein's life cycle: expression and folding. We observe improvements in both the folding and overall production of a model mechanosensitive channel protein, the mechanosensitive channel of large conductance, during cell-free reactions when vesicles containing diblock copolymers are present. By systematically tuning the membrane composition of vesicles through incorporation of a poly(ethylene oxide)-b-poly (butadiene) diblock copolymer, we show that membrane protein folding and production can be improved over that observed in traditional lipid vesicles. We then reproduce this effect with an alternate membrane-elasticizing molecule, C12E8. Our results suggest that global membrane physical properties, specifically available membrane surface area and the membrane area expansion modulus, significantly influence the folding and yield of a membrane protein. Furthermore, our results set the stage for explorations into how nonnatural membrane amphiphiles can be used to both study and enhance the production of biological membrane proteins. [ABSTRACT FROM AUTHOR]

This article describes the synthesis and characterization of a novel ‘schizophrenic’ diblock copolymer [poly(2-succinyloxyethyl methacrylate)-b-poly[(N-4-vinylbenzyl),N,N-diethylamine)]; PSEMA-b-PVEA] via reversible addition of fragmentation chain transfer (RAFT) polymerization technique. The chemical structures of all samples as representatives were characterized by means of Fourier transform infrared (FTIR), and 1H nuclear magnetic resonance (NMR) spectroscopies. The molecular weights of PHEMA and PVEA segments were calculated to be 9770 and 12,630 gmol−1, respectively, from 1H NMR spectroscopy. The self-assembly behavior of the synthesized PSEMA-b-PVEA diblock copolymer was investigated by means of 1H NMR spectroscopy, dynamic light scattering (DLS) measurements, and transmission electron microscopy (TEM) observation. The average sizes of the PSEMA-b-PVEA micelles at pHs 3.0, 6.0, and 10.0 were obtained to be 294, 237, and 201 nm, respectively, from DLS analysis. The zeta potential measurements at various pHs demonstrated that the synthesized PSEMA-b-PVEA diblock copolymer has zwitterionic properties, and the range of isoelectric point’s (IEP’s) was determined as 5.8–7.3. It is expected that the synthesized PSEMA-b-PVEA diblock copolymer considered as a prospective candidate in nanomedicine applications such as drug delivery, mainly due to its excellent ‘schizophrenic’ micellization behavior.

Fluorine-19 MRI is a promising noninvasive diagnostic method. However, the absence of a nontoxic fluorine-19 MRI tracer that does not suffer from poor biodistribution as a result of its strong fluorophilicity is a constant hurdle in the widespread applicability of this otherwise versatile diagnostic technique. The poly[N-(2-hydroxypropyl)methacrylamide]-block-poly[N-(2,2-difluoroethyl)acrylamide] thermoresponsive copolymer was proposed as an alternative fluorine-19 MRI tracer capable of overcoming such shortcomings. In this paper, the internal structure of self-assembled particles of this copolymer was investigated by various methods including 1D and 2D NMR, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS). The elucidated structure appears to be that of a nanogel with greatly swollen hydrophilic chains and tightly packed thermoresponsive chains forming a network within the nanogel particles, which become more hydrophobic with increasing temperature. Its capacity to provide a measurable fluorine-19 NMR signal in its aggregated state at human body temperature was also investigated and confirmed. This capacity stems from the different fluorine-19 nuclei relaxation properties compared to those of hydrogen-1 nuclei.

In this paper, we present an efficient numerical method for arbitrary shaped porous structure generation for 3D printing. A phase-field model is employed for modeling phase separation phenomena of diblock copolymers based on the three-dimensional nonlocal Cahn–Hilliard (CH) equation. The nonlocal CH equation is a fourth-order nonlinear partial differential equation. To efficiently solve the governing equation, an unconditionally gradient stable convex splitting method for temporal discretization with a Fourier spectral method for the spatial discretization is adopted. The standard fast Fourier transform is used to speed up the computation. A new local average concentration function is introduced to the original nonlocal CH equation so that we can locally control the morphology of the structure. The proposed algorithm is simple to implement and complex shaped structures can also be implemented with corresponding signed distance fields. Various numerical tests are performed on simple and complex structures. The computational results demonstrate that the proposed method is efficient to generate irregular porous structures for 3D printing.

This work studies the fast coupling reaction of polymers with a water competition under confined impinging jet (CIJ) mixing. The coupling reaction between polystyrene acyl chloride (PS-COCl) and polyethylene glycol amine (PEG-NH 2 ) is used either with or without a water competition. The reactions are implemented either in a molecular homogeneous and perfect mixing or in a CIJ mixing reactor. The simulations reveal that although the process with Re j  = 1770 is mixing limited ( τ rxn1 (∼1.8 ms) <  τ rxn2 (∼7.4 ms) <  τ mix (∼8.5 ms)), the desired coupling conversion (16%) and selectivity (0.17) is approaching to 18% and 0.19 respectively, which were their maxima occurred in a molecular homogeneous and perfect mixing. The simulation results successfully rationalize the low coupling conversion of about 17% reported in a previous experiment. Moreover, this study provides guidance to improve the desired conversion by increasing either [PEG-NH 2 ] 0 /[PS-COCl] 0 or k 2 / k 1 , which is crucial for the in-situ reactive flash nanoprecipitation (RFNP) to generate stable nanoparticles, especially with a higher drug load and less reactive polymers. The successful acquisition of the time scales of the competing reactions and mixing would be beneficial to revealing the mechanism and process of particle formation and evolution in the RFNP, where time scales of chemical reactions, mixing, and precipitation would compete to each other. [ABSTRACT FROM AUTHOR]

[Display omitted] • Facile synthesis of poly(2-(dimethylamino)ethyl methacrylate)- block -poly(4-vinylphenylboronic acid) diblock copolymers is achieved. • Recyclability of the nZVI (catalyst) and ionic liquid (solvent) is established. • The synthesized copolymer exhibited multi-stimuli responsivity against changes in pH, temperature and sugar concentration. A facile method based on recyclable nanoscale zero-valent iron (nZVI)-mediated photoRDRP in ionic liquid led to synthesis of narrow disperse poly(2-(dimethylamino)ethyl methacrylate) and poly(2-(dimethylamino)ethyl methacrylate)- block -poly(4-vinylphenylboronic acid) (PDMAEMA- b -PVPBA) diblock copolymers thereof. Stimuli response of the PDMAEMA- b -PVPBA copolymer against changes in pH, temperature and sugar concentration is assessed. Recyclability of the nZVI (catalyst) and ionic liquid (solvent) is established. Polymerization can be shut down or turned on simply by turning off or on the UV-A irradiation. This temporal control of the polymerization might be useful for wide use of the developed protocol for spatiotemporal "ON/OFF" control. DFT calculations are performed to get the geometry of the involved species. [ABSTRACT FROM AUTHOR]

Cell membrane receptors bind to extracellular ligands, triggering intracellular signal transduction pathways that result in specific cell function. Some receptors require to be associated forming clusters for effective signaling. Increasing evidences suggest that receptor clustering is subjected to spatially controlled ligand distribution at the nanoscale. Herein we present a method to produce in an easy, straightforward process, nanopatterns of biomolecular ligands to study ligand–receptor processes involving multivalent interactions. We based our platform in self-assembled diblock copolymers composed of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) that form PMMA nanodomains in a closed-packed hexagonal arrangement. Upon PMMA selective functionalization, biomolecular nanopatterns over large areas are produced. Nanopattern size and spacing can be controlled by the composition of the block-copolymer selected. Nanopatterns of cell adhesive peptides of different size and spacing were produced, and their impact in integrin receptor clustering and the formation of cell focal adhesions was studied. Cells on ligand nanopatterns showed an increased number of focal contacts, which were, in turn, more matured than those found in cells cultured on randomly presenting ligands. These findings suggest that our methodology is a suitable, versatile tool to study and control receptor clustering signaling and downstream cell behavior through a surface-based ligand patterning technique.

In this research contribution, nano-aggregates have been fabricated by introducing lanthanide (Ln3+) ions into solutions of amphiphilic diblock copolymers of polystyrene-b-poly (acrylic acid) (PS-b-PAA). The coordination of acrylic acid segments to lanthanide cations induces diblock copolymer (BCPs) self-assembly in order to design stable white luminescent hybrid nanoparticles with fine uniform particle size. The introduction of Ln3+ ions (Eu3+ and Tb3+) bestows the micelles, precisely white light, upon excitation of 342 nm. Lanthanide coordination cross-linking of poly (acrylic acid) segments, or blocks, endows the micelles higher thermal stability than that of BCPs micelles without cross-linking. As the most important key point of this work, the regular and stable nano-particles with high emission quality can make fully flexible electroluminescent devices with self-formation or uncoordinated into polymer hosts. Instead of inorganic luminescent nanoparticles with hard cores, this method can potentially apply for fully flexible white-light emitting diodes (FFWLEDs).

The present work deals with the building of novel, fully bio-based polyamide 11 (PA11)/polylactide (PLA) diblock copolymers (PA11 x PLA y ). The adopted two-step synthetic strategy involves first the preparation of an amino-terminated PA11 prepolymer ( i.e. , having the amino end-group available and the carboxylic one protected), to be employed subsequently as a macro-initiator in the ring-opening polymerization of d -lactide (or l -lactide). Upon tuning the lactide conversion, diblock copolymers with different PA11/PLA ratios are targeted and achieved, as demonstrated by 1 H NMR and TGA analysis. The thermal properties of these double-crystalline polymers are characterized by means of DSC. Finally, fast stereocomplexation is demonstrated upon mixing the enantiomeric PA11 x PLA y diblock pairs. Indeed, the idea behind these systems is to conjugate the properties of PLA with those of the high-performance PA11, in a cumulative rather than intermediate fashion, as for widely reported random poly(ester amide)s, but without phase separation occurring, which is the case for PLA/PA11 immiscible blends. In addition, the presence of the stereocomplex, well-known for its improved chemical/thermal resistance over PLA homopolymer, could impart even further quality to the final materials. [ABSTRACT FROM AUTHOR]

Alcohol-initiated ring-opening polymerization (ROP) of cyclic esters for synthesizing polyesters was well established, but amine-initiated ROP of cyclic esters was rare. A challenge is slow initiation and fast propagation in the amine-initiated ROPs. To address the difficulties, an ionic H-bond donor (iHBD) and H-bond acceptor (HBA) binary organocatalysis in amine-initiated ROP of lactide (LA) was developed. Guanidinium hexahydro-2 H -pyrimido[1,2- a ] pyrimidin-1-ium [(HppH 2 ) + ] and tertiary amine sparteine (SP), cooperatively played the role of iHBD/HBA binary catalysts, efficiently promoted ROP of LA from amine initiators toward polylactide (PLA) and polysarcosine- block -polylactide diblock copolymer (PSar- b -PLA). Benzyl amine and N -methylbenzylamine initiated ROPs of LA under mild conditions produced PLAs with predictable molecular weights ( M n,NMR  = 2.9–17.1 kg mol −1 ) and narrow dispersities ( Ð M,SEC  = 1.13–1.23). Macroinitiator PSar copolymerized with LA under the iHBD/HBA catalysis, producing PSar- b -PLAs with controlled molecular weights ( M n,NMR  = 5.7–14.8 kg mol −1 ) and low dispersities ( Ð M,SEC  = 1.16–1.21). Kinetics and chain extension experiments confirmed that the amine-initiated ROP of LA in presence of (HppH 2 ) + BF 4 − /SP was in controlled/living manner. 1 H NMR, 13 C NMR, SEC, and MALDI-ToF MS analyses indicated that the obtained PLA was exclusively initiated from the corresponding amine with amide linkage. An iHBD/HBA binary activation mechanism was proposed. [ABSTRACT FROM AUTHOR]

Encapsulation of proteins can be beneficial for food and biomedical applications. To study their biophysical properties in complex coacervate core micelles (C3Ms), we previously encapsulated enhanced green fluorescent protein (EGFP) and its monomeric variant, mEGFP, with the cationic-neutral diblock copolymer poly(2-methyl-vinyl-pyridinium)n-b-poly(ethylene-oxide)m (P2MVPn-b-PEOm) as enveloping material. C3Ms with high packaging densities of fluorescent proteins (FPs) were obtained, resulting in a restricted orientational freedom of the protein molecules, influencing their structural and spectral properties. To address the generality of this behavior, we encapsulated seven FPs with P2MVP41-b-PEO205 and P2MVP128-b-PEO477. Dynamic light scattering and fluorescence correlation spectroscopy showed lower encapsulation efficiencies for members of the Anthozoa class (anFPs) than for Hydrozoa FPs derived from Aequorea victoria (avFPs). Far-UV CD spectra of the free FPs showed remarkable differences between avFPs and anFPs, caused by rounder barrel structures for avFPs and more elliptic ones for anFPs. These structural differences, along with the differences in charge distribution, might explain the variations in encapsulation efficiency between avFPs and anFPs. Furthermore, the avFPs remain monomeric in C3Ms with minor spectral and structural changes. In contrast, the encapsulation of anFPs gives rise to decreased quantum yields (monomeric Kusabira Orange 2 (mKO2) and Tag red fluorescent protein (TagRFP)) or to a pKa shift of the chromophore (FP variant mCherry). [ABSTRACT FROM AUTHOR]

Recently, several thermogelling materials have been developed for biomedical applications. In this study, we prepared methoxy polyethylene glycol (MPEG)-b-(poly(ε-caprolactone)-ran-poly(2-chloride-ε-caprolactone) (PCL-ran-PfCL)) (MP-Cl) diblock copolymers at room temperature via the ring-opening polymerization of caprolactone (CL) and 2-chloride-ε-caprolactone (fCL) monomers, using the terminal alcohol of MPEG as the initiator in the presence of HCl. MPEG-b-(poly(ε-caprolactone)-ran-poly(2-azide-ε-caprolactone) (PCL-ran-PCL-N3)) (MP-N3) was prepared by the reaction of MP-Cl with sodium azide. MPEG-b-(poly(ε-caprolactone)-ran-poly(2-amine-ε-caprolactone) (PCL-ran-PCL-NH2)) (MP-NH2) was subsequently prepared by Staudinger reaction. MP-Cl and MP-N3 showed negative zeta potentials, but MP-NH2 had a positive zeta potential. MP-Cl, MP-N3, and MP-NH2 solutions formed opaque emulsions at room temperature. The solutions exhibited a solution-to-hydrogel phase transition as a function of the temperature and were affected by variation of the chloride, azide, and the amine pendant group, as well as the amount of pendant groups present in their structure. Additionally, the phase transition of MP-Cl, MP-N3, and MP-NH2 copolymers was altered by pendant groups. The solution-to-hydrogel phase transition was adjusted by tailoring the crystallinity and hydrophobicity of the copolymers in aqueous solutions. Collectively, MP-Cl, MP-N3, and MP-NH2 with various pendant-group contents in the PCL segment showed a solution-to-hydrogel phase transition that depended on both the type of pendant groups and their content. [ABSTRACT FROM AUTHOR]

A fluorescent diblock copolymer nanocomposite (DBCNC) was synthesized by ring opening polymerization (ROP) method using rhodamine 6G (R6G) dye as an initiator through bulk polymerization technique. ROP of caprolactone was carried out at 160°C for 2 h under nitrogen atmosphere in the presence of stannous octoate (Sn(Oct)2) as a catalyst followed by the ROP of tetrahydrofuran in the presence of phthalicanhydride as a co-monomer. Thus, synthesized fluorescent DBCNC was characterized by various analytical tools such as FTIR spectroscopy, UV–visible spectroscopy fluorescence emission spectroscopy, DSC, TGA and FESEM. The catalytic reduction of p-nitrophenol (NiP), Cr(VI) and R6G was carried out in the presence of DBCNC as a catalyst with the help of UV–visible spectrophotometer. The apparent rate constant (kapp) and induction time (Ti) were determined from the UV–visible spectral data. The nanosized V2O5 was prepared by a simple chemical reduction of bulk-sized V2O5 by using sodium borohydride (NaBH4) as a reducing agent. During the DBC formation, 0.01 g of nanosized V2O5 was added. This type of polymer supports the catalyst which is very much useful in the catalysis industry because of its easy separation and recyclable property. [ABSTRACT FROM AUTHOR]

Carbon fibers chemically grafted with hydroxyl-terminated diblock copolymer poly (n-butylacrylate)-b-poly (glycidyl methacrylate) (OH-PnBA-b-PGMA), were used as the reinforcement for epoxy composites. The multi-filament composite specimens were prepared and measured by dynamic mechanical analysis (DMA), to study the interfacial toughness of carbon fiber reinforced epoxy composites with the diblock copolymers. The loss modulus and loss factor peaks of β-relaxation indicated that composites with diblock copolymers could dissipate more energy at small strain and possess better interfacial toughness, whereas composites without the ductile block PnBA having the worse interfacial toughness. The glass transition temperature and the apparent activation energy calculated from the glass transition showed that the strong interfacial adhesion existed in the composites with diblock copolymers, corresponding with the value of interfacial shear strength. Therefore, a strengthening and toughening interfacial structure in carbon fiber/epoxy composites was achieved by introducing the diblock copolymer OH-PnBA-b-PGMA. The resulting impact toughness, characterized with an Izod impact tester, was better than that of composite without the ductile block PnBA.

Bimodal atomic force microscopy can provide high-resolution images of polymers. In the bimodal operation mode, two eigenmodes of the cantilever are driven simultaneously. When examining polymers, an effective mechanical contact is often required between the tip and the sample to obtain compositional contrast, so particular emphasis was placed on the repulsive regime of dynamic force microscopy. We thus investigated bimodal imaging on a polystyrene-block-polybutadiene diblock copolymer surface and on polystyrene. The attractive operation regime was only stable when the amplitude of the second eigenmode was kept small compared to the amplitude of the fundamental mode. To clarify the influence of the higher eigenmode oscillation on the image quality, the amplitude ratio of both modes was systematically varied. Fourier analysis of the time series recorded during imaging showed frequency mixing. However, these spurious signals were at least two orders of magnitude smaller than the first two fundamental eigenmodes. Thus, repulsive bimodal imaging of polymer surfaces yields a good signal quality for amplitude ratios smaller than A01/A02 = 10:1 without affecting the topography feedback.

Self-assembly of block copolymer/nanoparticle blends has promising applications in the design and fabrication of novel functional nanomaterials. Precise control of the spatial positions of nanoparticles within block copolymer-based nanomaterials is crucial to achieve some special physical properties and functions. Here, we employ the self-consistent field method to theoretically investigate the self-assembly of polymer grafted-nanoparticles in a diblock copolymer. It is found that by varying the size and selectivity of nanoparticles, one can not only produce various self-assembled nanostructures but also modulate the spatial positions of the nanoparticles, either at the copolymer interfaces or in the center of one copolymer phase, within the nanostructures. A denser grafted polymer brush plays a role of shielding effect on nanoparticles and can position them into the center of one copolymer phase. The nanostructural transition we observed is dictated by the competition between entropy and enthalpy. On the basis of a number of simulations, two phase diagrams of self-assembled nanostructures are constructed. This study may be helpful for optimal design of advanced materials with desired nanostructures and enhanced performance.

An amphiphilic diblock copolymer, dextran-block-poly(ε-caprolactone) (DEX-b-PCL), with a series of welldefined chain lengths of each block was prepared by conjugating a dextran chain with a PCL block via aza-Michael addition reaction under mild conditions. For the dextran block, samples with relatively uniform molecular weight, 3.5 and 6.0 kDa, were used, and the PCL blocks were prepared via ring-opening polymerization at defined ratios of ε-caprolactone to initiator in order to give copolymers with mass fraction of dextran (fDEX) ranging from 0.16 to 0.45. When these copolymers were allowed to self-assemble in aqueous solution, the morphology of assembled aggregates varied as a function of fDEX when characterized by transmission electron microscope (TEM), fluorescence microscope (FM) and dynamic laser scattering (DLS). As fDEX decreases gradually from 0.45 to 0.16, the morphology of the copolymer assembly changes from spherical micelles to worm-like micelles and eventually to polymersomes, together with an increase in particle sizes.

This article describes the synthesis and characterization of a novel ‘schizophrenic’ diblock copolymer [poly(2-succinyloxyethyl methacrylate)-b-poly[(N-4-vinylbenzyl),N,N-diethylamine)]; PSEMA-b-PVEA] via reversible addition of fragmentation chain transfer (RAFT) polymerization technique. The chemical structures of all samples as representatives were characterized by means of Fourier transform infrared (FTIR), and1H nuclear magnetic resonance (NMR) spectroscopies. The molecular weights of PHEMA and PVEA segments were calculated to be 9770 and 12,630 gmol−1, respectively, from1H NMR spectroscopy. The self-assembly behavior of the synthesized PSEMA-b-PVEA diblock copolymer was investigated by means of1H NMR spectroscopy, dynamic light scattering (DLS) measurements, and transmission electron microscopy (TEM) observation. The average sizes of the PSEMA-b-PVEA micelles at pHs 3.0, 6.0, and 10.0 were obtained to be 294, 237, and 201 nm, respectively, from DLS analysis. The zeta potential measurements at various pHs demonstrated that the synthesized PSEMA-b-PVEA diblock copolymer has zwitterionic properties, and the range of isoelectric point’s (IEP’s) was determined as 5.8–7.3. It is expected that the synthesized PSEMA-b-PVEA diblock copolymer considered as a prospective candidate in nanomedicine applications such as drug delivery, mainly due to its excellent ‘schizophrenic’ micellization behavior. [ABSTRACT FROM PUBLISHER]

We numerically investigate local defectiveness control of self-assembled diblock copolymer patterns through appropriate substrate design. We use a nonlocal Cahn-Hilliard (CH) equation for the phase separation dynamics of diblock copolymers. We discretize the nonlocal CH equation by an unconditionally stable 1nite difference scheme on a tapered trench design and, in particular, we use Dirichlet, Neumann, and periodic boundary conditions. The value at the Dirichlet boundary comes from an energy-minimizing equilibrium lamellar pro1le. We solve the resulting discrete equations using a Gauss-Seidel iterative method. We perform various numerical experiments such as effects of channel width, channel length, and angle on the phase separation dynamics. The simulation results are consistent with the previous experimental observations. [ABSTRACT FROM AUTHOR]

Recently, there has been renewed interest in the coupling between geometry and topological defects in crystalline and striped systems. Standard lore dictates that positive disclinations are associated with positive Gaussian curvature, whereas negative disclinations give rise to negative curvature. Here, we present a diblock copolymer system exhibiting a striped columnar phase that preferentially forms wrinkles perpendicular to the underlying stripes. In free-standing films this wrinkling behavior induces negative Gaussian curvature to form in the vicinity of positive disclinations. [ABSTRACT FROM AUTHOR]

To investigate the influence of the asymmetric ratio of polystyrene-block-poly(methyl methacrylate) (PS- b -PMMA) on the crystallization rate of polylactide (PLA), we synthesized PS- b -PMMA samples featuring distinct asymmetric ratios by using mercaptan/ε-caprolactam living polymerization and subsequently melt-blended the polymers with PLA. Optical micrographs showed that the PMMA block facilitated the dispersion of PS- b -PMMA in the PLA matrix because of the favorable miscibility between PLA and PMMA. The results of nonisothermal and isothermal experiments indicated that adding 0.5 wt% PS- b -PMMA increased the crystallization rate of PLA when the value of the asymmetric ratio was ⩽4. However, when the asymmetric ratio of PS- b -PMMA approached 6, the long-chain PMMA block retarded the chain mobility of PLA and lowered the crystallization rate. The results of polarization optical microscopy revealed that incorporation of PS- b -PMMA enhanced the crystallization rate of PLA through heterogeneous nucleation. The PS block in the PLA matrix provided the nucleation sites, whereas the PMMA block interacted with the PLA polymer chain and facilitated crystal growth. Lastly, wide-angle X-ray diffraction patterns suggested that incorporating PS- b -PMMA in the PLA matrix did not change the crystalline structure of PLA when the block-length ratio between PS and PMMA was varied. The asymmetric ratio of PS- b -PMMA strongly influenced the crystallization, and we optimized the asymmetric ratio of PS- b -PMMA in order to accelerate PLA crystallization. [ABSTRACT FROM AUTHOR]

Reversible addition-fragmentation chain transfer (RAFT) polymerisation was used to prepare novel amphiphilic poly(octadecyl acrylate)- block -poly(polyethylene glycol methyl ether acrylate) (P(ODA)- b -P(PEGA-OMe)) copolymers. These polymers were reduced to remove the dodecyl RAFT end-group, via radical-induced reduction using a hypophosphite salt, N -ethylpiperidine hypophosphite (EPHP). The resulting brush-like diblock copolymers were characterised by proton nuclear magnetic resonance ( 1 H NMR) and gel permeation chromatography (GPC). Investigation of the self-assembly behaviour of both the reduced and RAFT-group functional polymers in excess water determined by dynamic light scattering (DLS), cryo-transmission electron microscopy (cryo-TEM) and cross-polarised light microscopy (CPLM), indicated that all the copolymers form micellar aggregates in excess water. The hydrophobic dodecyltrithiocarbonate RAFT end-group, which is located on the terminal end of the hydrophilic domain, was found to influence the self-assembly behaviour of the copolymers in water. [ABSTRACT FROM AUTHOR]