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The Tarim area, characterized by deep reservoirs, high temperatures, and limited fresh water resources, necessitates a fracturing fluid system that exhibits excellent temperature shear resistance, low friction, and salinity tolerance. This study presents the development of a zwitterionic hydrophobic polymer, HPC-5, as an effective thickener using five types of polymeric monomers, including AM, AA, DMC, AMPS, and a non-ionic hydrophobic monomer. The method employed for synthesis was free-radical polymerization in solution. A series of experiments including viscosity measurement with variation of salinity, solubility and drag reduction test, crosslinking test, thermal and shear resistance, sand-carrying test, gel breaking evaluation, and core damage test were conduct under the simulated reservoir conditions. The zwitterionic design imparts great salt tolerance to HPC-5, and the apparent viscosities of HPC-5 solutions can maintain comparably high values with 10×104 ppm NaCl and CaCl2 concentration. Meanwhile, the molecules of HPC-5 associate with each other to form tight net structures, resulting in an excellent viscoelasticity of the solution. To achieve high pump rate during hydraulic fracturing operation in ultra-deep reservoirs, the delayed crosslinking agent ZDC-L was prepared for forming a delayed crosslinking gel fracturing fluid system using reservoir brine, and the drag reduction rate can reach over 70% before crossing link within 4 min. Under pH = 4 conditions, the crosslinking time can be significantly delayed to over 4 min while maintaining exceptional temperature resistance up to 160 ℃ for the gel. These properties make it highly suitable for hydraulic fracturing operations in ultra-deep wells with temperatures reaching up to 7000 m depth at pump rates of 4~5m3/min. [ABSTRACT FROM AUTHOR]

AbstractSpecifically, the conventional wood adhesive uses polyvinyl alcohol (PVA) as colloid to stabilise the polyvinyl acetate (PVAc) emulsion. Green materials are being used as a result of recent study on chemicals and alternative sources. This factor has made the substitution of sustainable biopolymers for petrochemicals considerably more important. An emulsifier, sodium lauryl sulphate (SLS), was used during the addition polymerization process to produce a hydroxyethyl cellulose-grafted-poly (vinyl acetate) (HEC-g-P(VAc)) emulsion from HEC and VAc. The purpose of the study was to increase the content of renewable materials in the emulsion. The adhesive films glass transition temperatures (Tg) have been identified via Differential Scanning Calorimetry (DSC). The performance of the PVAc emulsion-based adhesive in accordance with EN 204 and EN 205 standards was evaluated by measuring the tensile shear strength of wood joints under both dry and wet conditions. The viscosity of the adhesives significantly increased along with the addition of HEC. The application of HEC led to an increase in PVAc film hardness, which was confirmed by the film’s glass transition temperature. In an environment that was wet, after 24 h, the tensile strength of the sample containing HEC increased by 54% compared to a pristine sample, as per EN 204 and EN 205. Water resistance significantly increased in sample with HEC, as was found by measuring the water contact angle which is in line with wet strength. The overall study conclusion emphasises the superior water resistance and increased adhesion capabilities of PVAc emulsion-based wood adhesives stabilised by HEC. [ABSTRACT FROM AUTHOR]

Thermal frontal polymerization (FP) of acrylate monomers mixed with conventional peroxide initiators leads to significant bubble formation at the polymerizing front, limiting their practical applications. Redox initiators present a promising alternative to peroxide initiators, as they prevent the formation of gaseous byproducts during initiator decomposition and lower the front temperature, thereby enabling bubble-free FP. In this study, we investigate the FP of acrylate monomers of varying functionalities, including methyl methacrylate (MMA), 1,6-hexanediol diacrylate (HDDA), and trimethylolpropane triacrylate (TMPTA), using N,N-dimethylaniline/benzoyl peroxide (DMA/BPO) redox couple at room temperature and compare their front behavior, pot life, and bubble formation with those of same resin systems mixed with a conventional peroxide initiator, Luperox 231. The use of redox couples in FP of acrylates shows promise for rapid, energy-efficient manufacturing of polyacrylates and can enable new applications such as 3D printing and composite manufacturing. [ABSTRACT FROM AUTHOR]

Driving a car at extreme speeds, road holding, and sustainability do not go together well. Formula 1 racing is exciting but is not an example of sustainability. The aim of this work was to use materials, suitable for the treads of high-performance racing tyres, that can favour both high performance and sustainability. In particular, the objective was to achieve high dynamic rigidity at high temperatures (>100 °C) and a stable crosslinking network. A copolymer from an industrial waste such as sulphur and a comonomer from a circular biosourced material were used as the crosslinking agent of an elastomer composite based on poly(styrene-co-butadiene) from solution anionic polymerization and a carbon black with a high surface area. The biosourced circular material was 1,6-bis(2,5-dimethyl-1H-pyrrol-1-yl)hexane (HMDP), the di-pyrrole derivative of hexamethylenediamine. Two poly(S-co-HMDP) copolymers, with different S/HMDP ratios (6 and 8.9, Copolymer 1 and Copolymer 2) were carefully characterized by means of 1H-, 13C-, 2D1H-1H-COSY and 2D 1H-13C HSQC NMR. The comparison of the spectra highlighted the substitution with sulphur of the β-position of the pyrrole ring: mono-substitution largely prevailed in Copolymer 1 and also bi-substitution in Copolymer 2. The copolymers were used as additives in the vulcanization system. Compared with a reference composite, they allowed us to achieve more efficient vulcanization, a higher density of the crosslinking network, higher dynamic rigidity, better ultimate tensile properties, and better stability of the crosslinking network at high temperatures. Compared with a traditional oil-based crosslinking agent for elastomer composites with high rigidity and a stable structure at high temperatures, such as the perthiocarbamate 6-((dibenzylcarbamothioyl)disulfaneyl)hexyl 1,3-diphenylpropane-2-sulfinodithioate, the poly(S-co-HMDP) copolymers led to higher dynamic rigidity and better ultimate tensile properties. These improvements occurring simultaneously are definitely unusual. This work paves the way for the upcycling of circular materials in a large-scale application such as in tyres. [ABSTRACT FROM AUTHOR]

In this work, blends of monomer‐cast polyamide 6 (MCPA6) and polyurethane (TPU) were prepared by in situ anionic ring‐opening polymerization using caprolactam as the monomer and sodium hydroxide (NaOH) as the initiator. TPU degraded under weakly alkaline conditions to form an isocyanate group, which acted as a macromolecule activator to initiate the growth of the MCPA6 chain, and the formation of TPU‐co‐MCPA6 copolymer in this system, which improves the compatibility between MCPA6 and TPU. The MCPA6/TPU blends were tested for conversion, viscosity, and mechanical properties, and their structures and thermal properties were analyzed and evaluated by characterization techniques such as Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Simple and commercially available Lewis acids (LAs) are commonly used catalysts in anionic ring‐opening polymerization (AROP) reactions. In particular, for the AROP of epoxides, the addition of a Lewis acid allows the transition from a so‐called end‐chain mechanism to a monomer‐activated mechanism. The presence of the LA simultaneously leads to a decrease in the reactivity of active centers through the formation of a three‐species ate complex and to the activation of the monomer by LA coordination to the oxygen atom of the oxirane ring. These two effects result in both an increase in propagation kinetics and a decrease in transfer reactions, which has enabled the synthesis of high molecular weight polyethers. However, the impact of Lewis acids goes far beyond these classic effects. They have indeed enabled the polymerization of new functional monomers as well as the synthesis of heterotelechelic macromolecules. Also widely used as catalysts in copolymerization reactions (statistical, sequential, and alternating) Lewis acids can strongly influence the composition and sequence of monomer units in macromolecules. Finally, Lewis acids can also significantly influence the architecture of the obtained macromolecules. This review aims to list the various contributions of Lewis acids to macromolecular engineering and illustrate them with well‐chosen examples. [ABSTRACT FROM AUTHOR]

In this study, poly(n-isopropylacrylamide) (PNIPA) has been synthesized by the free-radical polymerization method using azobisisobutyronitrile the initiator. Then, nanoparticle-PNIPA composite is prepared with magnetic iron oxide (Fe3O4) nanoparticles synthesized by co-precipitation. The thermal decomposition kinetics of synthesized PNIPA and nanocoated PNIPA have been investigated. It has been observed that nanocoated PNIPA has a more stable structure at high temperatures than synthesized PNIPA. In the newly improved model equations relate to thermal decomposition kinetics, a special solution has been made with the new approach. Moreover, the calculated activation energies of the samples have been evaluated with response surface methodology (RSM). The ratios required to synthesize nanocoated-PNIPA under the optimum conditions have been determined by RSM. The activation energy of the nanocomposite obtains when 0.3170 g PNIPA is coated with 0.048 g Fe3O4 nanoparticle is determined as 127.757 kJ/mol. In other words, nanocoating has been increased the thermal stability of the synthesized composite. Poly (n-isopropylacrylamide) has been synthesized by free radical polymerization The Fe-O stretching vibration proves the existence of nanoparticle in FTIR spectra The thermal decomposition kinetics of synthesized PNIPA and Fe3O4-PNIPA nanocomposite have been evaluated by RSM. Magnetic nanoparticle reinforcement enhances the thermal stability of PNIPA [ABSTRACT FROM AUTHOR]

Using a novel technique, crosslinked gel polymer electrolytes (GPEs) designed for lithium-ion battery applications have been created. To form the photo crosslink via free-radical polymerization, a mixture of polyurethane acrylate (PUA), polyurethane methacrylate (PUMA), vinyl phosphonic acid (VPA), and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) was exposed to ultraviolet (UV) radiation during the fabrication process. The unique crosslinked configuration of the membrane increased its stability and made it suitable for use with liquid electrolytes. The resulting GPE has a much higher ionic conductivity (1.83 × 10−3 S cm−1) than the commercially available Celgrad2500 separator. A crosslinked structure formed by the hydrophilic properties of the PUA-PUMA blend and the higher phosphate content from BMEP reduced the leakage of the electrolyte solution while at the same time providing a greater capacity for liquid retention, significantly improving the mechanical and thermal stability of the membrane. GPP2 shows electrochemical stability up to 3.78 V. The coin cell that was assembled with a LiFePO4 cathode had remarkable cycling characteristics and generated a high reversible capacity of 149 mA h g−1 at 0.1 C. It also managed to maintain a consistent Coulombic efficiency of almost 100%. Furthermore, 91.5% of the original discharge capacity was maintained. However, the improved ionic conductivity, superior electrochemical performance, and high safety of GPEs hold great promise for the development of flexible energy storage systems in the future. [ABSTRACT FROM AUTHOR]

The strategy for the preparation of polyisobutylene‐based block copolymers via mechanistic transformation from cationic to radical polymerization is reported. This strategy involves the synthesis of 2‐bromo‐2‐methylpropanoyl‐terminated difunctional polyisobutylene macroinitiator (BiBB‐PIB‐BiBB) via consecutive cationic polymerization, in situ preparation of hydroxyl‐terminated polyisobutylene and its acylation by 2‐bromo‐2‐methylpropanoyl bromide. The Mn2(CO)10−triggered photo‐induced radical polymerization of styrene in bulk using this macroinitiator leads to the formation of multiblock copolymer, while predominantly triblock copolymer is generated during the polymerization of methyl methacrylate. The possibility to functionalize the polyisobutylene by pyrene via photo‐induced radical addition of 1‐bromomethyl pyrene in the presence of Mn2(CO)10 is also demonstrated in this work. [ABSTRACT FROM AUTHOR]

Amphiphilic block copolymers are promising candidates for the fabrication of ultrafiltration membranes with an isoporous integral asymmetric structure. The membranes are typically fabricated by the combination of block copolymer self‐assembly and the non‐solvent‐induced phase separation (SNIPS) process resulting in isoporous integral asymmetric membranes. Certainly, all these membranes lack thermal and chemical stability limiting the usage of such materials. Within this study, the fabrication of completely cross‐linked isoporous integral asymmetric block copolymer membranes is demonstrated by UV cross‐linking resulting in chemical and thermal stable ultrafiltration membranes. The UV cross‐linking process of PVBCB‐b‐P4VP (poly(4‐vinylbenzocyclobutene)‐b‐poly(4vinylpyridine)) block copolymer membranes in dependency of irradiation time, intensity, distance between membrane and UV source and the wavelength is investigated. Furthermore, it is shown that the penetration depths can be increased by soaking the membranes in wave‐guiding solutions before UV cross‐linking is carried out. Moreover, a completely new and easy cross‐linking strategy is developed based on isorefractive solvents resulting in thermal and chemically stable membranes that are cross‐linked through the whole membrane thickness. Finally, the new cross‐linking strategy in isorefractive solutions is transferred to commercial PVDF and PAN‐co‐PVC polymer membranes paving the way for more stable and sustainable ultrafiltration membranes. [ABSTRACT FROM AUTHOR]

Ni‐rich cathodes have been intensively adopted in Li‐ion batteries to pursuit high energy density, which still suffering irreversible degradation at high voltage. Some unstable lattice O2− species in Ni‐rich cathodes would be oxidized to singlet oxygen 1O2 and released at high volt, which lead to irreversible phase transfer from the layered rhombohedral (R) phase to a spinel‐like (S) phase. To overcome the issue, the amphiphilic copolymers (UMA‐Fx) electrolyte were prepared by linking hydrophobic C−F side chains with hydrophilic subunits, which could self‐assemble on Ni‐rich cathode surface and convert to stable cathode–electrolyte interphase layer. Thereafter, the oxygen releasing of polymer coated cathode was obviously depressed and substituted by the Co oxidation (Co3+→Co4+) at high volt (>4.2 V), which could suppressed irreversible phase transfer and improve cycling stability. Moreover, the amphiphilic polymer electrolyte was also stable with Li anode and had high ion conductivity. Therefore, the NCM811//UMA‐F6//Li pouch cell exhibited outstanding energy density (362.97 Wh/kg) and durability (cycled 200 times at 4.7 V), which could be stalely cycled even at 120°C without short circuits or explosions. [ABSTRACT FROM AUTHOR]

Moxifloxacin evaluation in pharmaceuticals and biological fluids is in high demand. It is important to fabricate a simple, sensitive, selective, miniaturized, and cost-effective chemical sensor to detect moxifloxacin in the environment. In this study, an electrochemical sensor based on molecularly imprinted polymer (MIP) was fabricated for the detection of moxifloxacin in which interdigital electrodes (IDEs) were used as transducers. Thermal free-radical bulk polymerization was used to synthesize MIP, methacrylic acid (MAA) was used as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, azobisisobutyronitrile (AIBN) as a free radical initiator, and dimethyl sulfoxide (DMSO) as a porogenic solvent in a poly (methacrylic acid) system for efficient recognition. The LCR meter was used to measure various electrical properties such as inductance and resistance. A concentration-dependent linear response was observed by the fabricated sensor having a lower limit of detection of 240 and 63 ppb for series and parallel resistance, respectively. Meanwhile, series and parallel inductance had lower detection limits of 48 and 8 ppb, respectively. Furthermore, in the presence of competing agents such as uric acid, ascorbic acid, and paracetamol, the fabricated sensor showed a selective response for moxifloxacin. The fabricated sensor also showed reversible and reproducible response. [ABSTRACT FROM AUTHOR]

This study focused on the thermal stability and the thermal degradation kinetics of two poly(vinyl ethers), PVEs, with different side groups. The objective was to determine how the nature of the side group affects the thermal properties of these materials. Poly(2–Phthalimide Ethyl Vinyl Ether), PPEVE, was derived via zirconocene–mediated cationic homopolymerization, and poly(2–Amino Ethyl Vinyl Ether), PAEVE, was obtained by hydrazinolysis of PPEVE. The thermal stability was investigated by employing thermogravimetric analysis (TGA) and differential thermogravimetry, DTG, at six different heating rates. The thermal decomposition kinetics data were evaluated using the Ozawa–Flynn–Wall, OFW, and Kissinger–Akahira–Sunose, KAS, "model-free" methods to calculate the activation energies, Ea , and subsequently the appropriate mathematical model or mechanism to describe the thermal decomposition process for each individual homopolymer. [ABSTRACT FROM AUTHOR]

The components synergistic affect the structure formation and complexity of anionic polymerization of blast furnace slag directly. The structure evolution of silicate polymerization with different i?2, to(MgO)/to( AI2O3 ) and to(Al2O3) changes was studied in this paper,thermodynamic calculation was used to determine the temperature rise regime and node for interrupting of the experiment. According to Raman spectrum analysis, it was found that when R2 and 00 (MgO)/oj( AI2O3 ) increased, the silicate anion groups in the blast furnace slag depolymerization occurred, and the structural units from Q4, Q3 to Qo, Qi and Q2 evolved, resulting in the deterioration of structural stability and the enhancement of slag fluidity. When the alkalinity is greater than 1. 2,ftj(MgO)/ftj(Al2O3) is greater than 0. 55, there is a reverse transformation or slowing trend. With the increase of ftj(Al2O3),it can be seen that the relative content of Qo changes little, the relative content of Qi increases first and then decreases, the relative content of Q2 decreases significantly,the relative content of Q3 increases significantly,the overall relative content of Q4 shows an increasing trends,the slag cluster structure tends to be complex,and the non-bridge oxygen content in the slag system shows a slow decreasing trend. When the content of to(Al2O3) exceeds 16%,the downward trend is more obvious. [ABSTRACT FROM AUTHOR]

Herein, an anionic polymerization method was employed to synthesize a series of amphiphilic poly(ethylene oxide-b-styrene-b-isoprene-b-styrene-b-ethylene oxide) penta-block copolymers (OSISO). Their molecular structure and properties were comprehensively characterized using GPC,1H-NMR, thermodynamic rheological testing and water contact angle test. Notably, the hydrophilic characteristics exhibited a proportional increase with the rise in poly(ethylene oxide) (PEO) content, ranging from 1.3 to 12.6 wt%. The polystyrene blocks with low number-average molecular weight (2000–3500) reduced the copolymer melt viscosity, surpassing a tenfold decrease than the control sample within the temperature range of 50–150 °C. Resultantly, this series of OSISO copolymers could be used to develop amphiphilic hot-melt pressure-sensitive adhesives (HMPSAs) by low temperature hot-melt processing method (<120 °C). HMPSAs loaded with 2 wt% of geniposide, prepared by an optimized composition formula of OSISO copolymers, tackifiers, and plasticizers (in a ratio of 5:5:2), displayed excellent in vitro drug release performance. Additionally, these adhesives presented impressive 180° peeling strength (0.05–0.14 kN/m) without residues left on the substrate in the 180° peeling tests. The incorporation of PEO block significantly enhanced both the adhesive properties and accumulative drug release. Geniposide showed a burst release behavior with a moderate accumulative drug release (15–30 wt%), attributed to the PEO phase without crystallization behavior of long PEO chains. [ABSTRACT FROM AUTHOR]

A low viscosity tetra‐functional cyclosiloxane epoxy resins (TGTS) is synthesized via a one‐step hydrosilylation reaction and cured separately with four different aromatic diamines to explore the reaction kinetics, network development, and thermal resistance. The hardeners used are 1,3‐phenylenediamine (PDA), diethyl toluene diamine (DETDA), 4,4‐diaminodiphenylmethane (DDM), and 1,3‐bis(4‐aminophenoxy) benzene, because of their availability and aromaticity. During cure with TGTS they all display autocatalytic behavior, but when compared to a traditional organic epoxy resin, diglycidyl ether of bisphenol A (DGEBA) cured with DDM however, the rate constants are about 3 times slower and less exothermic. The DETDA hardener in particular exhibits significantly slower rates of cure when compared to the other amines, being about an order of magnitude slower compared to the PDA curative. This is attributed to higher steric hindrance, compounded by reduced miscibility. The TGTS‐DDM carbon fiber composite displays the most thermal resistance after extended exposure to 220°C, producing the least mass loss and after combustion of about 12% compared to 20% for the DGEBA cured with DDM. The results presented here, illustrate that a tetrafunctional cyclic siloxane epoxy resin, can exhibit excellent processability, evidenced by very low viscosities and long gelation times, whilst also displaying excellent thermal resistance, whether at elevated temperature, or during combustion. [ABSTRACT FROM AUTHOR]

This study addresses the pressing need for enhancing the machining performance and hole quality of castamide by investigating the effects of solid lubricant addition and drilling parameters. Castamide, a highly crystalline polyamide synthesized via anionic ring‐opening polymerization, offers superior mechanical, physical, and chemical properties compared to conventional polyamide 6. However, its machining process, particularly drilling, remains a critical challenge due to its viscoelastic nature and sensitivity to heat generation. Using experimental investigations, thrust forces, drilling temperatures, hole geometry, and quality parameters are systematically analyzed and discussed. Notably, the study introduces Kestlub, a modified version of castamide with solid lubricant, and evaluates its drilling performance, a previously unexplored area in the literature. The research employs response surface methodology to model experimental data, considering both linear and quadratic effects of drilling parameters. Additionally, the significance of each parameter is assessed using ANOVA tables and Pareto charts, offering valuable insights into optimizing the drilling process for enhanced hole quality in castamide. It found that optimal drilling conditions occur at low rotational speeds and high feed rates, but thermal damage, influenced by factors like thermal conductivity and transition temperature, affects hole geometry and burr formation. Highlights: Drilling performances of solid lubricant reinforced castamides were investigated.Drilling temperatures were recorded with a thermal camera and differential scanning calorimeter and thermal gravimetric analyses were performed.Drilling properties were analyzed statistically according to the response surface method.It found that optimal drilling conditions occur at low rotational speeds and high feed rates. [ABSTRACT FROM AUTHOR]

In order to provide more evidence to understand the termination mechanism in styrene free‐radical polymerization, (1‐bromoethyl) benzene and polystyrene with bromide end group (PSt‐Br) synthesized by atom transfer radical polymerization (ATRP) were used as the model compound and model polymer to study the termination behavior of styrenic radical by atom transfer radical coupling (ATRC), and then the NMR chemical shifts of the head‐to‐head enchainment from coupling termination were obtained. SEC and different NMR measurement methods were used to analyze and characterize the products. It is confirmed that there is no bimolecular disproportionation termination between styrenic free radicals, but only coupling termination to form the head‐to‐head enchainment. The proton and carbon chemical shifts of the head‐to‐head enchainment from coupling termination for (1‐bromoethyl) benzene are 2.7–2.86 ppm and ~47.3 ppm. As for the polystyrene through ATRC from PSt‐Br, the corresponding chemical shifts are 2.61–3.29 ppm and ~46.4 ppm, respectively, they are almost the same as the data in our previous paper (~3.05 ppm, ~46.6 ppm) for polystyrene initiated by BPO, proving that the chain termination in free‐radical polymerization of styrene initiated by BPO occurs through primary termination between chain radical and primary radical rather than bimolecular termination between chain radicals. [ABSTRACT FROM AUTHOR]

The transition to a sustainable future requires the use of waste‐free technologies for production. Potentially, additive technologies can be a promising approach for accessing circular economy due to the precise amount of feeding materials and the absence of molds. However, the initial feeding materials for additive approaches are often based on non–renewable hydrocarbon sources. This work focused on the use of polymers derived from terpene alcohols to develop a filament suitable for 3D printing. Initially, the vinylation of menthol using calcium carbide was optimized and scaled up, then a series of terpenyl–based vinyl ethers were obtained under optimal conditions. The cationic polymerization of vinyl ethers was also scaled up and resulted in 99 % yield of the polymers, which was subsequently subjected to hot extrusion. The initial terpenol was used as an additive to increase polymer flexibility. The addition of menthol (30 wt %) to polyvinyl menthol led to the suitable filament. Using the filament, a series of objects were 3D printed at 125 °C. The material demonstrated good sinterability and adhesion to glass and shrinkage comparable to that of commercial 3D printing filaments. Furthermore, the polymers obtained were used as additives to enhance the adhesion of commercially available filaments. [ABSTRACT FROM AUTHOR]

Potassium diphenyl phosphide (KPPh2), which forms a highly nucleophilic phosphide anion, was used as an initiator for the anionic ring-opening polymerization of glycidyl phenyl ether (GPE). GPE was selected as a model compound for the practical application of various glycidyl-type epoxy resins. MALDI-TOF MS analysis of the resulting polymer clarified the presence of a diphenyl phosphine moiety at initiation, confirming that the anionic polymerization was initiated by nucleophilic attack of the phosphide anion on the epoxide. In addition, compared to various basic catalysts such as phosphines and amines, KPPh2 catalyzed the ring-opening addition of epoxide with o-cresol much more efficiently, demonstrating its potential for application to epoxy–phenol curing systems. [ABSTRACT FROM AUTHOR]

Anisotropy in naturally occurring or synthetic microcellular structures is an important feature for the development of materials with high specific stiffness and strength, in addition to creating materials with unique physical properties. Polymeric foams constitute a broad class of materials that are widely used for their advantages of low density, high specific mechanical properties and high insulative properties. Traditional synthetic routes are slow, energy demanding processes that employ the use of high temperature ovens, freezers, or high‐pressure equipment. Herein we present a convenient and energy efficient method to produce anisotropic high performance polymeric foams via rapid radically induced cationic frontal polymerization coupled with chemical blowing agents. The degree of pore orientation and degree of anisotropy are a result of the propagating front working in concert with the foam volume expansion. This paper presents results into FP foam formation to illustrate how changes in boundary conditions and front initiation position affect both the microcellular structure and their resulting physical and mechanical properties. Additionally, results are presented to show how changes in resin formulation, such as the addition of nanoparticles affect both properties as well as the microcellular structure and anisotropy. [ABSTRACT FROM AUTHOR]

In this work, FR‐PNX, an alkylphosphate oligomer was introduced into rigid polyurethane foam (RPUF) to fabricate FR‐PNX/RPUF composites. The flame retardancy, thermal stability, and combustion properties of composites were investigated by limiting oxygen index (LOI), thermogravimetric (TG), microcalorimetry (MCC), scanning electron microscopy (SEM), et al. The flame retardancy tests demonstrated that the incorporation of 50 phr of FR‐PNX yielded composites that the highest LOI of 23.6 vol% and achieved a V‐0 rating in the UL‐94 test. TG results indicated that FR‐PNX promoted the decomposition of FR‐RPUF in the process, but enhanced the high‐temperature stability of the composites. MCC analyses revealed that the addition of FR‐PNX suppressed the heat release during combustion, and FR‐PNX50/RPUF exhibited the lowest total heat release of 17.3 MJ/m2, a 35% reduction compared to the pure sample. Moreover, the peak heat release rate was decreased to 83.1 W/g, representing a 46.9% reduction compared to pure RPUF. SEM and Raman analyses of the char residue demonstrated that the incorporation of FR‐PNX facilitated the formation of a dense and continuous char layer in the FR‐RPUF, with increased graphitization degree of the char layer, thereby enhancing the composite's fire resistance through the development of a more stable fire barrier. [ABSTRACT FROM AUTHOR]

Difunctional glycidyl azide polymer (GAP) is an energetic binder promising for propellant formulations. The multifunctional fluorine‐containing GAP has been synthesized to enhance its mechanical properties. This work outlined multifunctional GAP partially grafted with 1,2,3‐triazole‐5‐(α‐hydroxyl)‐fluorinated polyether (GAP‐g‐3F) synthesized by thermal and catalyst‐free azide‐alkyne cycloaddition reaction, in which the azide groups were from GAP and electron‐deficient alkynes from β‐propargyl‐α‐hydroxyl poly (tri‐fluoropropane glycidyl ether) (PHP3F). PHP3F was synthesized via the typical cationic ring‐opening polymerization of 2‐((2,2,2‐trifluoroethoxy) methyl) oxirane and propargyl alcohol as the initiator. The chemical structures, molecular weight, and thermal properties were characterized by FTIR, NMR, GPC, DSC, and TGA, respectively. HNMR results showed that 8 % of total azide groups in GAP were grafted. GAP‐g‐3F had a slightly higher glass transition temperature than that of GAP. The results of TGA showed that GAP‐g‐3F had suitable thermal decomposition resistance up to 200 °C. The thermal properties, mechanical properties, cross‐linking network structures, and microstructures of the polyurethane networks cured with hexamethylene diisocyanate trimer as a crosslinking agent were determined and compared by TGA, universal tensile test, swelling measurement, and SEM, respectively. The initial decomposition temperature of GAP‐g‐3F‐based polyurethane networks (GAP‐g‐3F‐PU) was around 220 °C, thus meeting the requirements for propellants. In addition, GAP‐g‐3F‐PU exhibited superior mechanical properties, showing an almost twelvefold increase in tensile strength to 16.9 MPa compared with difunctional GAP‐PU with 1.4 MPa tensile strength. The results of the swelling measurement revealed that the GAP‐g‐3F‐PU sample showed a higher crosslinking density in comparison to the GAP‐PU sample. SEM results indicated that the multifunctional fluorine‐containing GAP could enhance compatibility between the soft and hard segments of polyurethanes, leading to a decrease in their separation degree. This finding showed that the synthesis of a multifunctional GAP partially grafted with fluorinated polyether via a triazole ring may be a promising solution to decrease the separation degree increase of PUs, thereby improving the mechanical properties. [ABSTRACT FROM AUTHOR]

Elastomers based on cross‐linked bottlebrush polymers combine an extreme softness at low strains with a strain‐stiffening effect, which makes them attractive as active components in dielectric elastomer actuators (DEA). Their main disadvantage concerns the small relative permittivity, which is about 3.5, requiring relatively high driving voltage in actuators. We synthesized a bottlebrush polymer elastomer with polar brushes, which exhibit an enhanced dielectric permittivity of 4.4. Anionic ring‐opening polymerization of a polar cyclosiloxane gave telechelic polar brushes, while ring‐opening polymerization of a norbornene macromonomer gave a bottlebrush polymer which was cross‐linked to elastomers by a thiol‐ene reaction. Elastomers with a small elastic modulus below 100 kPa, strain at break exceeding 100 %, attractive elasticity, and small mechanical loss factors (tanδ) were achieved. Temperature‐dependent impedance measurements revealed a transition temperature of −95 °C and an interfacial polarization. The multigram scale synthesis demonstrates the potential for scaling up, which opens the door to broader applications of these materials beyond actuators, such as capacitive sensors, batteries, and electroluminescent devices. Notably, these devices operate at extremely low voltages where the dielectric breakdown does not limit their functionality, but still, the softness and the increased dielectric permittivity are a plus. [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]

Objective: To investigate the expression of mi R-195 and mi R-3653 in glioma tissue and to analyze their relationship with clinicopathological features and prognosis of glioma. Methods: Collected paraffin specimens of 42 glioma patients who underwent surgical resection at The Seventh Affiliated Hospital of Guangxi Medical University from January 2016 to June 2019 as the glioma group, and another 30 patients with traumatic brain injury who underwent surgical treatment during the same period were selected, and the paraffin specimens of the frontal or temporal lobe tissue removed during surgery were used as the control group. The relative expression of mi R-195 and mi R-3653 in glioma group and control group were detected by real-time fluorescent quantitative polymerization chain reaction (qRT-PCR), and the relationship between the expression of mi R-195 and mi R-3653 and the clinicopathological characteristics of glioma were analyzed. The relationship between mi R-195, mi R-3653 expression and prognosis in glioma patients was analysised by Kaplan Meier survival curve. The factors affecting the prognosis of glioma patients were analysised by Multivariate Cox regression. Results: The expression level of mi R-195 and mi R-3653 in glioma group were lower than those in control group (P＜0.001). There were significant differences in mi R-195 expression among patients with different pathological grades and distant metastasis (P ＜0.001). There were significant differences in mi R-3653 expression among patients with different tumor diameter,pathological grade and distant metastasis (P＜0.001). Kaplan-Meier survival curve showed that the three years survival rate of mi R-195and mi R-3653 low expression group were lower than those of mi R-195 and mi R-3653 high expression group (P＜0.05). Multivariate Cox regression analysis showed that distant metastasis, pathological grade III-IV level, low mi R-195 expression, and low mi R-3653expression were risk factors for the prognosis of glioma patients (P＜0.05). Conclusion: The low expression of mi R-195 and mi R-3653 in glioma patients is associated with distant metastasis, pathological grading of grade III-IV level, and low survival rate, mi R-195 and mi R-3653 may become prognostic indicators and therapeutic targets for glioma. [ABSTRACT FROM AUTHOR]

Polyolefin‐b‐poly(ethylene oxide) (PEO) represents the most widely investigated amphiphilic block copolymers. So far, one‐pot continuous synthesis of such hybrid block copolymers has only been fulfilled by anionic polymerization through sequential addition of vinyl monomers and ethylene oxide (EO). It still remains challenging to achieve altogether high block efficiency, high polymerization efficiency, and high molar mass for PEO. Here, we report a one‐pot hybrid block copolymerization approach to polyisoprene/polystyrene(PI/PS)‐b‐PEO, in which PI/PS are formed by sBuLi‐initiated anionic vinyl‐addition polymerization, then in situ employed as macroinitiators for the anionic ring‐opening polymerization (ROP) of EO aided by an organic Lewis pair. The cooperative (dual‐ion‐complexing) catalytic effect of organobase and triethylborane is proven, for the first time, effective for lithium alkoxide initiator system, allowing to achieve at room temperature high ROP activity (complete EO conversion and PEO of 3–64 kg/mol reached in 1–6 h), narrow molar mass distribution, controlled block lengths and composition. Density functional theory calculation shows that phosphazene bases are particularly effective, compared with N‐heterocyclic bases, for complexing with Li+ and enhancing the nucleophilicity of oxyanion. The rate of ROP is also affected by Li+‐induced aggregation of the chain‐end ion pairs, which though can be offset by adequate catalyst loadings. The versatility of this approach is further demonstrated in the one‐pot synthesis of tri‐/tetrablock ter‐/quaterpolymers constituted by PI, PS, PEO, and poly(propylene oxide). Of great interest, PS‐b‐PI‐b‐PEO triblock terpolymer with a specific composition is found to form internally microphase‐separated micellar aggregates when dispersed in water. [ABSTRACT FROM AUTHOR]

In the current study, a novel radical‐induced cationic frontal polymerization (RICFP) concept capable of rapid curing at room temperature via visible light irradiation is represented. Initially, the optimal formulation, which can be most effectively cured with visible light irradiation, is determined based on thickness, hardness, curing speed, and mechanical properties using FT‐IR, DSC, TGA, and flexural test methods. Subsequently, the viability of the method is illustrated by fabricating glass fiber‐reinforced composites through the hand lay‐up technique, employing the optimized formulation and glass fibers in various forms (chopped strand mat and biaxial). Mechanical properties of the obtained composites, including bending, tensile, and shear tests, are carried out according to relevant international standards and compared with reference composites thermally cured with amine‐based hardener by conventional method. [ABSTRACT FROM AUTHOR]

Herein, a novel, highly branched and photoresponsive polysiloxane is synthesized and studied. The polymer is photoconstructed into a single‐chain nanoparticle loaded with Nile Red and Metformin. Through the photoreversible [2+2] mechanism of the polymer's pendant coumarin moieties, the nanoparticles are de‐crosslinked, and their cargo molecules released. A study of the kinetics of release is undertaken in different solvents, providing insight into the relationship between the cargo's molecular structure and that of the polymer chain. On the whole, this report's study introduces new controlled release and cationic ring‐opening polymerization concepts while providing the first example of a single‐chain polymer nanoparticle based on a photoresponsive polysiloxane. [ABSTRACT FROM AUTHOR]

Polyvinylpyrrolidone (PVP) exhibits remarkable qualities; owing to the strong affinity for water of its pyrrolidone group, which enhances compatibility with aqueous systems, it is effective for stabilizing, binding, or carrying food, drugs, and cosmetics. However, coating the surface of polymeric films with PVP is not practical, as the coatings dissolve easily in water and ethanol. Poly(silane–pyrrolidone) nano/microparticles were prepared by combining addition polymerization of methacryloxypropyltriethoxysilane and N-vinylpyrrolidone, followed by step-growth Stöber polymerization of the formed silane–pyrrolidone monomer. The silane–pyrrolidone monomeric solution was spread on oxidized polyethylene films with a Mayer rod and polymerized to form siloxane (Si-O-Si) self-cross-linked durable anti-fog thin coatings with pyrrolidone groups exposed on the outer surface. The coatings exhibited similar wetting properties to PVP with significantly greater stability. The particles and coatings were characterized by microscopy, contact angle measurements, and spectroscopy, and tested using hot fog. Excellent anti-fogging activity was found. [ABSTRACT FROM AUTHOR]

Dielectric spectroscopy (DS) was employed to monitor the isothermal polymerization processes of P(MCA‐DEGDMA) formed by the alternating copolymerization of methyl cyanoacetate (MCA) and diethylene glycol dimethacrylate (DEGDMA) at different temperatures in real time. P(MCA‐DEGDMA) is a polyether containing functional groups (O, CN, COOCH3) which can promote the transport of ions Li+, thereby having the potential to apply in polymer electrolytes. It is beneficial to investigate the effect of temperature and time on P(MCA‐DEGDMA) polymerization and choose a suitable synthesis strategy through dielectric monitoring. A time‐ and temperature‐dependent relaxation process induced by orientational polarization of the P(MCA‐DEGDMA) chain was observed over a frequency range from 10 kHz to 4 × 106 Hz. The time to reach polymerization equilibrium (tequ) and the dielectric conversion were determined through the time variations of the conductivity at low frequency (κl). The polymerization process shows the characteristic of "fast followed by slow," and the tequ can be advanced by raising the polymerization temperature. In addition, by discussing the monitoring time dependence of relaxation time (τ) and permittivity (ε), it was concluded that the extent of polymerization (α) for P(MCA‐DEGDMA) at 40°C is the largest, and the optimal polymerization temperature is between 30 and 50°C. Furthermore, the free activation energy (ΔG), activation enthalpy (ΔH), and activation entropy (ΔS) of the relaxation process caused by the motion of the P(MCA‐DEGDMA) chain in three temperature ranges (10–20°C, 30–40°C, 50–60°C) were calculated by using Eyring's equation, from which the physical image of various structures and conformations of the P(MCA‐DEGDMA) chain during monitoring was proposed. Considering the effect of temperature on the generation and migration of free ions, and on the structure and conformation of the P(MCA‐DEGDMA) chain, some suggestions for the synthesis of P(MCA‐DEGDMA) are given: during the polymerization, the temperature is controlled at 10°C in the early stage and then gradually raised to 40°C, which may be beneficial to improving the extent of polymerization of P(MCA‐DEGDMA). Our work may be helpful to investigate the polymerization process of polyether obeying the same synthesis mechanism with P(MCA‐DEGDMA). It can be proven that DS is useful in detecting the inner information of the system changing over time through our work. [ABSTRACT FROM AUTHOR]

Controlling the end‐groups of biocompatible polymers is crucial for enabling polymer‐based therapeutics and nanomedicine. Typically, end‐group diversification is a challenging and time‐consuming endeavor, especially for polymers prepared via ionic polymerization mechanisms with limited functional group tolerance. In this study, we present a facile end‐group diversification approach for poly(2‐oxazoline)s (POx), enabling quick and reliable production of heterotelechelic polymers to facilitate POxylation. The approach relies on the careful tuning of reaction parameters to establish differential reactivity of a pentafluorobenzyl initiator fragment and the living oxazolinium chain‐end, allowing the selective introduction of N‐, S‐, O‐nucleophiles via the termination of the polymerization, and a consecutive nucleophilic para‐fluoro substitution. The value of this approach for the accelerated development of nanomedicine is demonstrated through the synthesis of well‐defined lipid‐polymer conjugates and POx‐polypeptide block‐copolymers, which are well‐suited for drug and gene delivery. Furthermore, we investigated the application of a lipid‐POx conjugate for the formulation and delivery of mRNA‐loaded lipid nanoparticles for immunization against the SARS‐COV‐2 virus, underscoring the value of POx as a biocompatible polymer platform. [ABSTRACT FROM AUTHOR]

Alkyl borane compounds‐mediated polymerizations have expanded to Lewis pair polymerization, free radical polymerization, ionic ring‐opening polymerization, and polyhomologation. The bifunctional organoborane catalysts that contain the Lewis acid and ammonium or phosphonium salt in one molecule have demonstrated superior catalytic performance for ring‐opening polymerization of epoxides and ring‐opening copolymerization of epoxides and CO2 than their two‐component analogues, i.e. the blend of organoborane and ammonium or phosphonium salt. To explore the origin of the differences of the one‐component and two‐component organoborane catalysts, here we conducted a systematic investigation on the catalytic performances of these two kinds of organoborane catalysts via terpolymerization of epoxide, carbon dioxide and anhydride. The resultant terpolymers produced independently by bifunctional and binary organoborane catalyst exhibited distinct microstructures, where a series of gradient polyester‐polycarbonate terpolymers with varying polyester content were afforded using the bifunctional catalyst, while tapering diblock terpolymers were obtained using the binary system. The bifunctional catalyst enhances the competitiveness of CO2 insertion than anhydride, which leads to the premature incorporation of CO2 into the polymer chains and ultimately results in the formation of gradient terpolymers. DFT calculations revealed the role of electrostatic interaction and charge distribution caused by intramolecular synergistic effect for bifunctional organoborane catalyst. [ABSTRACT FROM AUTHOR]

Whereas the cationic homopolymerization of β-pinene and isobutene (IB) have been extensively studied, their copolymerization is still very scarce, and the conditions under which copolymerization can occur are limited to extremely low temperatures. Moreover, the application of the copolymer has not been reported. Here, a series of room-temperature copolymerizations of β-pinene and IB, using group 13 compounds as catalysts, were conducted. The copolymerizations yielded a low molecular weight (Mn ~ 103) and a narrow molecular weight distribution (Mw/Mn < 2.0) copolymer, with a satisfactory yield at various comonomer feeds, and their glass transition temperature was predictable from the comonomer composition. Furthermore, the tackifying property of the obtained copolymer was investigated using a 180° peel adhesion test. A blend polymer of the copolymer and a styrene-isoprene triblock copolymer showed a high peeling force (0.58 ± 0.14 N/10 mm) and a glass transition temperature low enough for its application as a pressure-sensitive adhesive. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) is known for its excellent overall properties and is widely used as a degradable material. However, PLA has poor toughness due to its inherent brittleness and low ductility. Poly(butylene adipate-co-butylene terephthalate) (PBAT) has good toughness and can be used to toughen PLA, while the poor compatibility between the two materials leads to ineffective toughening of PLA by PBAT, which needs to be modified by adding compatibilizers during processing. In this study, high-toughness PLA-based blends were prepared by in-situ polymerization using lactide as the reactive monomer and PBAT as the toughening agent, with the addition of industrial-grade epoxy oligomers ADR and PLA-PBAT-PLA triblock copolymers as solo or synergistic compatibilizers, to investigate the effects of ADR and PLA-PBAT-PLA on the compatibility and properties of PLA and PBAT. The inclusion of compatibilizers enhanced the interfacial bonding between PLA and PBAT and boosted the toughness of PLA/PBAT blends, and the addition of 0.15 wt% ADR or 0.15 wt% PLA-co-PBAT resulted in the impact strength of PLA/PBAT (75/25) blends reaching 150.09 kJ/m2 and 100.39 kJ/m2, respectively. The epoxy group of ADR reacted with the terminal hydroxyl or terminal carboxyl group of PLA and PBAT to form a chemical bond, which enhanced the melt strength and water absorption. PLA-PBAT-PLA forms a block structure between PLA and PBAT, which improves the fluidity and tensile strength of the blends. These findings provide fundamental data for PLA/PBAT compatibility studies and provide further development for PLA blend modification studies. [ABSTRACT FROM AUTHOR]

Liquid crystal polyesters (LCPs) have attracted growing attention due to the increasing demand for military equipment and 5G communication devices. Commonly, the LCPs are polymerized by transesterification reaction catalyzed through inorganic salts, however, the effects of anionic pairs of catalysts on the LCP polymerization have not been studied carefully. Herein, five kinds of sodium salts with varied anionic pairs as catalysts to facilitate LCP polymerization are investigated for the first time. The catalytic activity is analyzed by the evolution of the liquid crystal (LC) phase during polymerization based on the thin-film polymerization technique. The temperature from 190 °C to 270 °C and the catalyst content in the range from 0 to 0.1 wt% are compared, demonstrating that temperature at 270 °C and catalyst content at 0.1 wt% are the best polymerization conditions for all sodium salts. It is found that sodium formate has the best catalytic activity for the polymerization of LCP in all experimental conditions, in comparison with sodium acetate, sodium propionate, sodium butyrate, and sodium p-hydroxybenzoate. The successful polymerization is also determined by FT-IR spectra, performing the declined intensity of vibration peak at 1370 cm−1 ascribed to the vanishment of acetoxy groups as well as the enhanced intensity of vibration peak at 1735 cm−1 ascribed to the formation of ester groups. [ABSTRACT FROM AUTHOR]

Thermoplastic resin transfer molding (T‐RTM) is one of the composites manufacturing processes using anionic ring‐opening polymerization of ε‐caprolactam (CPL). Because of very fast reaction among materials, traditional T‐RTM requires two different channels before transferring resin into the mold cavity. Single‐stream method has been researched for robust and simple process, which has several advantages in aspect of manufacturing process. Carbon fibers were preprocessed including polyamide sizing, plasma treatment and activator sizing for modified single‐channel T‐RTM. Through quantitative calculation of required sizing content, concentration of sizing agent was controlled. Thermal stability of preprocessed carbon fibers during molding was measured by TGA. Crystallinity of anionic‐polyamide 6 (A‐PA6) manufactured by single‐stream T‐RTM was measured by DSC and 3.0% lower than traditional T‐RTM. Mechanical properties were measured, which are short‐beam strength and flexural strength/modulus. The short‐beam strength and flexural strength of the composites fabricated through single‐stream T‐RTM were 29.7% and 17.0% higher than those fabricated through conventional T‐RTM while strain and toughness decreased. Fracture surface of carbon fibers/A‐PA6 composites manufactured by single‐stream T‐RTM showed more adhesive bonding between carbon fiber and matrix. Highlights: Surface treatment on carbon fibers to develop single‐channel T‐RTM process.Effects of surface treatment researched by thermal, quantitative, and IR analysis.Improved interfacial fracture mechanisms due to higher adhesion at the interface. [ABSTRACT FROM AUTHOR]

Polymer composites offer numerous benefits, including low cost, easy processability, and diverse applications. In this work, we fabricated a composite material with high thermal conductivity and electromagnetic interference (EMI) shielding performance using EGaIn, a liquid metal (referred to as LM in this paper), MXene (MX), and expanded graphite (EG) as multifunctional fillers, along with polyacrylic acid (PAA). LM was used to exfoliate MX under the effect of shear force, which not only reduced the size of MX but also increased the aspect ratio of the 2D‐structured MX. MX was filled into the pores of EG to make a heat transfer path, thereby enhancing its thermal conductivity, mechanical properties, and EMI SE properties. LM served as the initiator of free‐radical polymerization to convert acrylic acid (AA) into PAA. Finally, the LMMX/EG/PAA composite was hot‐pressed to make the heat‐transfer path dense. As a result, the LMMX/EG/PAA composite exhibited a thermal conductivity of 1.88 W/m·K and an EMI shielding effect of 52 dB. [ABSTRACT FROM AUTHOR]

Functional polymers play an important role in various biomedical applications. From many choices, poly(2-isopropenyl-2-oxazoline) (PIPOx) represents a promising reactive polymer with great potential in various biomedical applications. PIPOx, with pendant reactive 2-oxazoline groups, can be readily prepared in a controllable manner via several controlled/living polymerization methods, such as living anionic polymerization, atom transfer radical polymerization (ATRP), reversible addition–fragmentation transfer (RAFT) or rare earth metal-mediated group transfer polymerization. The reactivity of pendant 2-oxazoline allows selective reactions with thiol and carboxylic group-containing compounds without the presence of any catalyst. Moreover, PIPOx has been demonstrated to be a non-cytotoxic polymer with immunomodulative properties. Post-polymerization functionalization of PIPOx has been used for the preparation of thermosensitive or cationic polymers, drug conjugates, hydrogels, brush-like materials, and polymer coatings available for drug and gene delivery, tissue engineering, blood-like materials, antimicrobial materials, and many others. This mini-review covers new achievements in PIPOx synthesis, reactivity, and use in biomedical applications. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotube (MWCNT)/polypyrrole nanotube (PPyNT)/triiron tetraoxide (Fe3O4) composites with a sword‐sheath structure are added to a UV‐curable resin to form a unique highly microwave‐absorbing material with a low absorbent content. Specifically tailored for high‐precision stereolithography three‐dimensional (3D) printers, the low absorbent content ensures an efficient curing and molding of the photosensitive resin. The conducting polymer polypyrrole is coated on the MWCNTs via free‐radical polymerization, forming a sheath structure. The initiator of the free‐radical polymerization, FeCl3, is converted into Fe3O4 and loaded onto the sheath structure. This ternary composite material is uniformly dispersed in the photosensitive resin with interconnected sword‐sheath structures, ensuring a favorable dielectric loss performance even at a low absorbent content. Importantly, the material exhibits both dielectric loss and magnetic loss properties. Using a UV‐cured microwave‐absorbing material with an absorbent content of 0.5 wt%, an electromagnetic loss of −22.5 dB can be achieved with a thickness of 1 mm. This UV‐cured microwave‐absorbing material facilitates the high‐precision 3D printing of microwave structures with various intricate shapes, broadening the application scope of microwave‐absorbing materials. [ABSTRACT FROM AUTHOR]

Light‐mediated 3D printing techniques have gained significant interest due to the inherent advantages of light as external stimuli, including spatiotemporal control and easy access. As 3D printing processes require rapid polymerization, free radical or cationic polymerization methods are used. However, these polymerization reactions are limited to the production of materials with properties that cannot be chemically altered post‐printing. In this work, a rapid, open‐to‐air photo‐controlled cationic reversible addition‐fragmentation chain‐transfer polymerization of vinyl ethers is demonstrated in the presence of a three‐component photoinitiating system comprising a photosensitizer, electron donor, and acceptor as co‐initiators under the irradiation with blue light. The polymerization mechanism shows rapid kinetics and controlled, living polymerization characteristics. Trithiocarbonate chain ends of poly(isobutyl vinyl ethers) are reactivated to produce block copolymers with cyclohexyl vinyl ethers. The rapid kinetics and water tolerance of the reported system enable the 3D printing of polymeric solids under ambient (e.g., room temperature and open to air) conditions, followed by the effective reactivation of trithiocarbonate chain ends to post‐synthetically modify the object with an acrylate‐based fluorescent monomer via a controlled radical polymerization strategy. [ABSTRACT FROM AUTHOR]

In vinyl/divinyl copolymerization, a crosslink is formed by the reaction between an active center and a pendant double bond. When both the active center and the pendant double bond are located within the same polymer molecule, the cyclization occurs, which is ineffective for growth in molecular weight. In the present model, the network dimension theory is applied to estimate the mean‐square radius of gyration for the growing polymer molecule, which is used to account for the enrichment effect of pendant double bonds around the active center for the cyclization reaction. The model is applied to the miniemulsion copolymerization, and both conventional free‐radical polymerization and ideal living polymerization are considered. Some of important characteristics of network architecture formed in these two types of polymerization mechanisms that cannot be predicted based on the classical chemical kinetics can be reproduced by the model, such unique characteristics as the pendant double bonds are consumed from the beginning of polymerization in the conventional free‐radical polymerization but not so in the living polymerization. The present model provides useful insights into the size and structural dependent network formation kinetics without relying on the lattice model. [ABSTRACT FROM AUTHOR]

The polymerization mechanism of 2-vinylpyridine catalyzed by cationic yttrium complexes with diverse ancillary ligands, specifically [L¹Y(CH2SiMe3)(THF)]+ [L¹ = (2,6-Et2C6H3)NC(Me)CHC(Me)N(2,6-Et2C6H3)] (Y-1), [L²Y(CH2SiMe3)(THF)]+ [L² = (2,6-Cl2C6H3)NC(Me)CHC(Me)N(2,6-Cl2C6H3)] (Y-2), and [L³Y (CH2SiMe3)(THF)]+ [L³ = (2,6-C6H5)NC(Me)CHC(Me)N(2,6-iPr2C6H3)] (Y-3), was studied using density functional theory (DFT) calculations. Having achieved an agreement between theory and experiment, it is found that isotactic selectivity induced by Y-1 or Y-2 results from a combination of smaller deformation of the catalyst and stronger electronic effects. Conversely, the Y-3 complex exhibits comparable energy barriers for proceeding via either isotactic or syndiotactic pathways, aligning with the production of atactic polymers as seen experimentally. To examine the steric effects on the kinetic and thermodynamic properties, a computational model of an analogue complex [L4Y(CH2SiMe3)(THF)]+ [L4 = (2,6-Cl2C6H3)NC (Me)CHC(Me)N(iPr2C6H3)] (Y-4), featuring increased steric hindrance, was analyzed. Distortion-interaction and topographic steric map analyses further affirmed that steric hindrance significantly influences stereoselectivity. A direct relationship was identified between the energy barriers of isotactic insertion transition states and the bulkiness of ancillary ligands; greater distortion energy of the catalyst correlates with higher barriers for isotactic polymerization. These findings enhance the mechanistic comprehension of 2-vinylpyridine polymerization and are expected to contribute valuable insights for the improvement of catalytic polymerization systems of 2-vinylpyridine. [ABSTRACT FROM AUTHOR]

This study focuses on how catalyst concentration, activator concentration, and initial polymerization temperature impact in‐situ anionic ring‐opening polymerization (AROP) of ω‐lauryllactam. Catalyst and activator roles are fulfilled by NaH and toluene‐2,4‐diisocyanate (TDI), respectively, with varying catalyst/activator ratios to assess the influence of a bifunctional activator on the polymerization process. The materials produced undergo a thorough analysis, with a specific emphasis on solidification time. The examination extends to scrutinizing how different concentrations of catalyst/activator and polymerization temperatures affect crucial physical and chemical parameters. The study identifies NaH‐6 mol%/TDI‐3 mol% as the optimal formulation for solidification among the three explored temperatures. Notably, at 180 and 200°C, PA12 exhibits enhanced monomer conversion when a catalyst/activator ratio of 1.7 or 2 is applied. These findings underscore the significant impact of the catalyst/activator ratio and their individual concentrations on the polymer's final properties. This influence extends to factors such as crystallinity, polymer chain regularity, and dynamic mechanical properties. Additionally, the experimental conditions utilized for anionic polymerization are observed to shape the characteristics of PA12. [ABSTRACT FROM AUTHOR]

In conventional foams, anisotropy within the microcellular structure can only be achieved through confinement in one or more directions during the foaming process. Herein, we present a novel, versatile, and energy efficient method to create unique high‐performance foams where the anisotropy of the microcellular and the microcellular structure itself is not dictated by external confinement during the foaming process. To generate such foams, an initial crosslinked gel is first created where the crosslink density of the gel can be tuned by UV intensity and cure time. Next, the gel can be foamed while simultaneously creating a second network via radically induced cationic frontal polymerization (RICFP). In this case, the anisotropy in the foam is dictated by propagation front during the RICFP and the microcellular morphology and cell surface area are dictated by the crosslink density of the gel. These two unique qualities lead to rigid foams that can be generated from a gel without the need for confinement where the microcellular size and shape can be tuned by the crosslink density of the gel precursor. A one‐pot liquid system composed of miscible epoxies, acrylates, and chemical blowing agents (CBAs), allows for control over the foam physical, mechanical, and thermal properties with glass transition temperatures ranging from 74.7 to 125.8°C. Additionally, by patterning the crosslink density of the initial gel through controlled exposure of UV, complex microcellular structures can be formed that are not possible in conventional foaming processes. This positions gel frontal polymerization and foaming as an advanced technique to produce high performing anisotropic foams with a wide array of tunable physical, mechanical, and thermal properties. [ABSTRACT FROM AUTHOR]

Radiation-initiated cross-linking polymerization of multifunctional monomers is an attractive method used for drying solvent-free liquid coatings, inks, and adhesive as well as for fabricating high-performance composite materials. The method offers a number of advantages compared with thermal curing processes. Free radical and cationic polymerization have been investigated in detail over the past years. A high degree of control over curing kinetics and material properties can be exerted by adjusting the composition of matrix precursors and/or by acting on the process parameters (overall dose, dose rate, dose increment, initial temperature). Several pending issues that require deeper investigations are as follows: (i) the fast polymerization of multifunctional monomers generates micro-heterogeneous networks requiring detailed characterization and quantification by microscopic, thermal, and spectroscopic analyses; (ii) the adhesion and surface properties of radiation-cured coatings are quite sensitive to processing parameters; and (iii) significant enhancement of the toughness is needed to qualify potential matrices based on simple difunctional monomers for high-performance composites. Recent results show that the bulk and surface properties of radiation-cured materials can be improved by advanced formulation of matrix precursors and by a parametric study of the processing factors. [ABSTRACT FROM AUTHOR]

Reversible addition‐fragmentation chain‐transfer polymerization, or RAFT, is a method for the controlled synthesis of block copolymers and an alternative to living ionic polymerizations. Although it is less susceptible to impurities, oxygen leads to inhibition of the polymerization. In a previous study, a model was developed to describe the inhibition kinetics of the RAFT polymerization of styrene. Based on this model, a detailed sensitivity analysis is performed with respect to the kinetic coefficients. While the formation of polyperoxides by oxygen addition shows high reaction rates, their further reactions (growth and termination) could be identified as rate‐determining steps. In addition, a proportional dependence of the duration of inhibition on the oxygen concentration was found. Based on the knowledge gained, a new initiation strategy with different thermal initiators to optimize polymerization was successfully tested using simulations. [ABSTRACT FROM AUTHOR]

The tacticity of vinyl polymers is a key factor affecting the properties of materials. Recently, organic Brønsted acids have been demonstrated as effective catalysts for the development of highly stereoselective cationic reversible addition-fragmentation chain transfer (RAFT) polymerizations of vinyl ethers, in which the use of RAFT agents could allow the control the molecular weight and tacticity of polymer products simultaneously. However, the effect of RAFT agents on the tacticity-regulation remains elusive and lacks of investigation. In this study, we synthesized four types of RAFT agents and evaluated their influence in the stereoselective cationic polymerization of isobutyl vinyl ether in the presence of PADI as a Brønsted acid catalyst, which unveils that the Z group of RAFT agents could not only affect the polydispersity of the products, but also exert a profound effect on the stereoselectivity. After extensive screening of the RAFT agents, high stereoregularity (isotacticity, 90% m) was obtained when using dithiocarbonate ester-type RAFT agents with a benzyloxy Z group. [ABSTRACT FROM AUTHOR]