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Statistical and block copolymers of n‐hexyl isocyanate (HIC) and 2‐chloroethyl isocyanate (ClEtIC) were synthesized via cοοrdination polymerization employing the half‐titanocene complex [(η5‐C5H5)((S)‐2‐Bu‐O)TiCl2] as initiator. The complex, bearing a chiral substituent, led to optically active products, as confirmed by circular dichroism measurements. The molecular characterization of all products was carried out by NMR and IR spectroscopy and size exclusion chromatography (SEC), while their thermal stability was investigated through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and differential thermogravimetry (DTG). The reactivity ratios of the two monomers were determined using various graphical methods, as well as the COPOINT program, according to the terminal copolymerization model. Structural parameters, such as the dyad monomer sequences and the mean sequence lengths were calculated as well. In addition, the kinetics of the thermal degradation of the statistical copolymers was studied, and the activation energies of the thermal degradation were calculated employing the Kissinger, Ozawa–Flynn–Wall (OFW), and Kissinger–Akahira–Sunose (KAS) methods. The block copolymers were synthesized by sequential addition of monomers starting from the polymerization of HIC. Well‐defined products were obtained in a controlled way as revealed by SEC, IR, and NMR measurements. [ABSTRACT FROM AUTHOR]

The rapid and painless dressing change is a global challenge in wound management due to the traditional ways of dressing change often cause secondary damage on newly formed skin tissue. Recently, researchers have shown great interest in the development of on‐demand dissolvable hydrogel dressings that can be rapidly and safely dissolved under specific stimuli. These hydrogel dressings possess multifunctional properties, including injectability, self‐healing capacity, anti‐inflammation, antioxidation, and angiogenesis capabilities, which have successfully promoted healing for various types of wounds. In this review, we summarize current methods for fabricating on‐demand dissolvable hydrogels dressings, which include two strategies: (1) chemical stimuli, involving the introduction of external dissolving agents; (2) physical stimuli, where stimuli are applied without the use of dissolving agents. These approaches can decrease the density of cross‐links, resulting in the dissolution of hydrogel dressings. The advantages and drawbacks of these on‐demand dissolvable hydrogels dressings for promoting wound healing are discussed and addressed. The development and challenges for the clinical application of on‐demand dissolvable hydrogel dressings are prospected. [ABSTRACT FROM AUTHOR]

Traditional living/controlled cationic polymerization provides a simple synthetic route for the preparation of various polymers with set molecular weight, narrow molecular weight distribution, and clear structure. Nowadays, under the requirements of sustainable development, it is very important to explore the green chemical technology in depth. This review offers an overview of initiation systems, reaction media, polymerization techniques, and monomers, with the aim of summarizing environmentally friendly methods utilized in the field of cationic polymerization over the past 15 years. It covers a variety of directions from traditional initiation systems to green initiators, from corrosive solvents to environmentally friendly solvents, from drop initiation to external stimulation initiation, from petroleum fractionated monomers to bio‐based monomers. These methods and Techniques aim to develop advanced high‐quality polymer products using cationic polymerization, and achieving efficient energy savings and reducing emissions. The ongoing exploration of green‐controlled cationic polymerization holds promise for opening up new avenues and novel technology for high‐performance polyolefin materials. [ABSTRACT FROM AUTHOR]

Fused deposition modeling (FDM), an advanced 3D printing method, is a rapidly growing technology for realizing geometrically complex parts. FDM utilizes a thermoplastic feedstock that is heated and extruded through a nozzle to build up layers of material following toolpaths prescribed by three‐dimensional (3D) data. However, the rapid thermal cycles that the material undergoes during this process limit the formation, growth, and entanglement of the molecular chains in the material. Herein, we have proposed a novel laser‐assisted fused deposition modeling (LAFDM) process for the improvement in printed part properties such as bond width and tensile strength. The LAFDM system was developed consisting of an infrared CO2 laser, coupled with an industrial FDM printer. Using an adapted tensile testing method, the bond strength between deposited layers of acrylonitrile butadiene styrene (ABS) in 3D‐printed structures was assessed. Thermogravimetric analysis was used to monitor the thermal stability of the polymer to detect alterations to the chemical composition of the material as a result of the processing conditions. A 9.5% increase in the average bond tensile strength for the LAFDM‐printed specimen was observed compared to that of the non‐laser‐assisted FDM‐printed specimen. The improvement to the bond strengths was achieved without compromising the thermal stability of the polymer. [ABSTRACT FROM AUTHOR]

In the rapidly advancing era of intelligent technologies, the development of advanced materials characterized by high performance and functionality is considered a crucial aspect. A series of high‐performance functional polymers known as cis/trans‐tetraphenylethene‐containing poly (p‐phenylene terephthalamide) (cis/trans‐TPE‐PPTA), has been developed. These polymers exhibited typical aggregation‐induced emission (AIE) characteristics along with exceptional electrical and mechanical properties. It has been observed that addition ratios of cis/trans‐TPE‐2NH2 as the comonomer significantly influenced the properties of the cis/trans‐TPE‐PPTA paper. Specifically, when compared with pure poly (p‐phenylene terephthalamide) (PPTA), the homogeneous trans‐TPE‐PPTA paper at 10% trans‐TPE‐2NH2 addition ratio, fabricated using a hot‐pressing method, demonstrated significantly improved overall performance, including a substantial increase in tensile strength (97.4%) and dielectric strength (41.5%), as well as other favorable properties. This enhancement suggests promising prospects for numerous applications. [ABSTRACT FROM AUTHOR]

Polymer agglomeration is a useful way to enlarge the particle size of polybutadiene latex (PBL). However, the agglomeration process is very complex and is affected by many factors. Therefore, it is difficult to predict the mean particle size and distribution of agglomerated PBL. This study proposed a novel simulation method based on the artificial neural network (ANN) model. Firstly, the influence of agglomeration conditions on the particle size of agglomerated PBL were investigated, including the particle size of pre‐agglomerate PBL, the amount, the α‐methacrylic acid (α‐MAA) content, the solid content and the particle size of agglomerating agent. It is found that these factors have a close nonlinear relationship with the mean particle size and polydispersion index (PDI) of agglomerated PBL. Then, a model containing 236 data points was built using ANN including these properties as input with mean particle size and PDI of agglomerated PBL as output. The coefficient of determination (R2) values predicted by ANN for training, validation, test and total data are 0.9879, 0.9964, 0.9930, and 0.9902, respectively. It indicates that there is a good agreement between experimental data and predicted results by ANN. This study demonstrates that a simple machine learning method has good performance in predicting the particle size of agglomerated PBL, which further improves the development efficiency of PBL polymer agglomeration. [ABSTRACT FROM AUTHOR]

Gelatin‐methacryloyl (GelMA) hydrogel has gained huge success in the last decades thanks to its versatilities in many applications. Notably, one of them is 3D bioprinting, as GelMA physical‐mechanical properties and biocompatibility of uncured formulation perfectly suit the requirements of a bioink. Nevertheless, before the photopolymerization, the hydrogel shows weak mechanical properties and long recovery time after stress application, which results in the inability to obtain complex and self‐standing forms due to structure collapse. In this work, Carbopol ETD 2020 NF, dissolved in cell culture medium, was used as supporting bath to optimize GelMA bioprinting and overcome its stability limitations. The achieved results demonstrated the possibility of printing shapes containing hollows with lumens or non‐planar surfaces, also by using nozzles with larger inner diameter, which reduced cell death during printing process, but were usually avoid because of low resolution. Moreover, constructs' extraction was easier when Carbopol solution was prepared in culture medium rather than in water, reducing sample handling. In conclusion, thanks to this supporting bath, it was possible to print cellularized scaffold, with channels that were then seeded, obtaining inner structure. Further, this Carbopol formulation could be considered an eligible candidate as a supporting bath to obtain GelMA 3D self‐standing‐shaped and vascularized scaffold. [ABSTRACT FROM AUTHOR]

To improve the therapeutic efficiency of paclitaxel (PTX) and reduce its toxicity to normal tissues, a novel hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) derivative has been designed and developed. The polymer (bio‐HP‐β‐CD(NAC)‐PLA) is synthesized by modifying HP‐β‐CD with polylactic acid, cysteine, and biotin. Using bio‐HP‐β‐CD(NAC)‐PLA as the carrier, a PTX‐loaded nanoparticulate system is developed by a modified emulsion solvent evaporation method. The optimized drug‐loaded nanoparticles are obtained with a mean diameter of 162.4 nm and drug loading of 16.1%. In vitro drug release study exhibits that PTX is released in a redox‐dependent manner. Cellular uptake study suggests that the bio‐HP‐β‐CD(NAC)‐PLA nanoparticles can be specifically taken up by MCF‐7 cells via the biotin receptor‐mediated endocytosis. In vitro and in vivo anticancer efficacy evaluations demonstrate the superior antitumor activity and negligible toxicity of the PTX‐loaded nanoparticles. It can be concluded that the proposed polymer bio‐HP‐β‐CD(NAC)‐PLA offers a promising drug delivery system for targeted delivery and controlled release of PTX. [ABSTRACT FROM AUTHOR]

Block polyethers comprised of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEG or PEO) segments form the basis of ABA‐type PEO‐b‐PPO‐b‐PEO poloxamer materials. The inverse architecture with an internal hydrophilic PEO segment flanked by hydrophobic blocks can be difficult to prepare with control of architecture by use of traditional anionic polymerization. These oxyanionic polymerizations are plagued by chain‐transfer‐to‐monomer side reactions that occur with substituted epoxides such as propylene oxide (PO). Herein, we report a new method for the preparation of block polymers through a controlled polymerization involving a N‐Al Lewis adduct catalyst and an aluminum alkoxide macroinitiator. The Lewis pair catalyst was able to chain‐extend commercial PEO macroinitiators to prepare di‐, tri‐, and pentablock polyethers with low dispersity and reasonable monomer tolerance. Chain extension was confirmed using size exclusion chromatography and diffusion ordered nuclear magnetic resonance spectroscopy. The resulting block polymers were additionally analyzed with small‐angle X‐ray scattering to correlate the morphology to molecular architecture. [ABSTRACT FROM AUTHOR]

With the development of heat and creep‐resistant UHMWPE fiber via UV crosslinking, its structure‐properties evolution during processing needs attention. The structures of UHMWPE fiber in different forms, the pre‐oriented yarn (POY), the full stretch yarn (FDY) and UV crosslinked FDY (UVFDY), obtained from our pilot line were systematically studied with differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), small‐angle X‐ray scattering (SAXS), and solid‐state 13C NMR. Additionally, the heat and creep resistance of UVFDY were evaluated by the temperature at break (Tb), glass transition temperature (Tg), time at break (tb) for a given aging temperature, and creep elongation (Lc). The results demonstrated that UVFDY possessed high gel content (89.0%), high crystallinity (84.2%), and high orientation (91.7%). These characteristics caused UVFDY not only with excellent mechanical properties but also process extraordinary heat and creep resistance, especially for its much higher Tb (220 °C), Tg (−75.7 °C) and tb (20 h) while lower Lc (7.8%), comparing with FDY (Tb = 158 °C, Tg = −86.8 °C, tb = 1.3 h and Lc = 38.2%). This work provides insights into the structure‐properties relationship of UVFDY, which will aid in the development of UV crosslinked UHMWPE fiber with better heat and creep resistance. [ABSTRACT FROM AUTHOR]

High‐performance fibers are used in fire‐protective garments due to their exceptional thermal stability and mechanical performance. However, these garments suffer from a reduction in their performance over their lifetime. The purpose of this study was to investigate the hydrothermal aging of 15 yarns contained in eight fabrics made of different fiber blends. The accelerated hydrothermal aging was performed via immersion in reverse osmosis (RO) and acidic water at temperatures between 40 °C and 90 °C for up to 1200 h. The resulting mechanical, chemical, and physicochemical changes in the yarns and fabrics were assessed. The result showed a large drop in the breaking force of yarns made from para‐aramid/polybenzimidazole (PBI) fiber blends in all aging water conditions. For the other fabrics, aging in acidic water and a jar with the PBI‐containing fabrics generally caused a larger decrease in strength compared to aging in RO water in a separate jar. The results also showed that a change in crystallinity rather than in chemical structure appeared to be the cause for the changes in tensile strength after hydrothermal aging. The findings of this study will contribute to identifying strategies to improve the long‐term performance of fire‐protective fabrics. [ABSTRACT FROM AUTHOR]

Bacterial infections are common during skin wound healing, which can interrupt the healing process, delay wound healing and seriously affect the quality of life. Long‐term antibiotic treatment may lead to the development of drug resistance. Traditional bandages, sponges, films, and textiles are commonly single‐functional, and usually fail to satisfy the complicated needs of wound healing process. In recent years, antibacterial hydrogel dressings have received extensive attention for treatment of infected and chronic wounds, which can serve as biocompatible, multifunctional platforms for both promoting tissue regeneration and inhibiting bacterial infection. Cationic polymers with inherent antibacterial properties have been used as the hydrogel backbone, and metal ions and metal nanoparticles can be loaded in the hydrogels to enhance the antibacterial effects. Besides, various drugs and bioactive factors have been incorporated to provide the hydrogel with anti‐inflammatory and antioxidant activities in complicated environment of chronic wound healing. Additionally, the tissue adhesion of hydrogel dressings can have advantages in fixing the dressings at wound sites and promoting the dressing‐tissue interactions. In this review, we focus on the designing strategies for tissue‐adhesive, antibacterial, naturally‐derived polymer hydrogels for treating infected and chronic wounds. The typical tissue adhesion mechanisms and antibacterial mechanisms of the hydrogel dressings are summarized. Finally, the prospects and challenges in the further development of multi‐functional hydrogels to treat infected and chronic wounds are proposed. [ABSTRACT FROM AUTHOR]

This paper presents a systematic review of the literature on the melt memory effects observed in polymers, an area that has engendered considerable debate for over 50 years. Recent advances in experimental techniques have provided fresh insights into how a polymer's thermal history influences its recrystallization behavior. It has been observed that given other conditions unchanged, the crystallization temperature during recrystallization decreases with an increase in the melt temperature Ts above the melting point Tm until a critical melt temperature is attained. This phenomenon also extends to the half‐time of crystallization and the secondary structures, such as lamellar thickness, of semi‐crystalline polymers. Despite these findings, a comprehensive constitutive model that encapsulates polymer melt memory effects remains elusive. Cutting‐edge instrumentation, including in situ small and wide‐angle X‐ray scattering, temperature‐controlled Fourier transform infrared spectroscopy, and flash differential scanning calorimetry, have posed significant challenges to the traditional nucleation and growth models established in the 1970s. These models are foundational to our understanding of polymer crystallization, which is an integral part of polymer processing and production. In this review, the historical contours of this discourse are traced, with an examination of both the recent experimental breakthroughs and theoretical advancements pertinent to polymer melt memory effects. This paper delves into the prevailing theories of polymer nucleation and crystallization and engages with theoretical discussions and numerical simulations that attempt to elucidate and rationalize these melt memory phenomena. [ABSTRACT FROM AUTHOR]

The preparation of four types of epoxidized iron‐based comb butadiene‐isoprene rubber (EBIR) with different epoxidation degrees (4.7%, 6.4%, 10.2%, and 12.3%) was investigated for the first time in this study. The modification involved the use of hydrogen peroxide and formic acid as raw materials for the epoxidation process. Following this, silica/EBIR composites were prepared by mixing EBIR with silica nanoparticles, without the use of a silane coupling agent (SCA). The objective was to investigate the influence of the epoxidation degree on the structure and properties of the resulting silica/EBIR nanocomposites. The results indicated that the introduction of epoxy groups had a positive effect on the interfacial interaction between the rubber and filler, leading to improved dispersion of the silica nanoparticles in the rubber matrix. Consequently, the tensile properties, wet skid resistance, and abrasion resistance of the silica/EBIR composites were found to be superior to those of the un‐epoxidized silica/BIR composites. Furthermore, comparing the silica/EBIR‐12.3 nanocomposites with silica/BIR‐Si69 nanocomposites, it was revealed that silica/EBIR‐12.3 showed a 69.4% enhancement in wet skid resistance and an 8.0% reduction in rolling resistance. These findings demonstrate the potential of silica/EBIR composites for high‐performance tire tread rubber applications, offering environmental benefits and improved properties. [ABSTRACT FROM AUTHOR]

We explore the crystal structure and ionic conductivity of unfilled and cellulose nanowhisker‐filled polymer electrolytes, based on high molecular weight PEO and LiClO4 at a concentration EO:Li = 6:1 (EO = ether oxygen). At this concentration, the polymer electrolyte forms crystalline PEO6 (PEOy—the crystal structure co‐crystallizes "y" PEO ether oxygens to one Li‐anion pair). While the diffraction patterns for PEO3 and PEO6 with LiClO4 are available, their structures are not. Thus, we optimize these structures using density functional theory and show agreement between simulated and experimental diffraction patterns. The PEO6 crystal shows insufficient Li‐ion conductivity due to a lack of percolated conduction paths, and the crystal structure is unstable following 2 months after annealing. Cellulose nanowhiskers, with their patterned surface OH groups, extend the length of PEO6 tunnels, stabilize these tunnels for as long as a year, and result in the percolation of crystals. Although the EO:Li = 6:1 stoichiometry should not favor PEO3 formation, we observe this crystal phase in some unfilled samples. But, with the addition of nanowhiskers, the patterned surface templates PEO6 formation rather than PEO3. Despite these advantages, nanowhiskers do not improve ionic conductivity as hypothesized. The tools developed in this work allow further mechanistic exploration of conduction through crystalline domains. [ABSTRACT FROM AUTHOR]

Microgels have a wide range of applications, from catalysis to biomedical applications such as drug delivery in dispersion, or as surface‐attached materials to improve the biocompatibility of implants or as anti‐fouling coatings. The first aim of this work is to understand the morphology of the supramacromolecular, tannic acid (TA) crosslinked microgels using two‐dimensional 1H NMR spectroscopy, and relaxometry. The second aim is to study the volume phase transition (VPT) of TA‐crosslinked microgels with different crosslinker densities in dispersion using NMR. In this context, 1H high‐resolution NMR spectroscopy is used in combination with the two‐state model and the Boltzmann sigmoidal function to determine thermodynamic quantities of the VPT, such as temperature (Tt), width of transition (ΔTt), and change in entropy (ΔS). Third, surface‐deposited microgels are characterized in terms of their VPT using a quartz crystal microbalance (QCM‐D) to study the properties of these microgels for applications where they are used as coatings. Finally, the Tt of microgels supramolecular crosslinked with TA are compared with microgels covalently crosslinked with N,N′‐methylenebisacrylamide (BIS) in dispersion, using NMR, and deposited on a surface, using QCM‐D. For this purpose temperature‐responsive poly(N‐vinylcaprolactam) and poly(N‐isopropylacrylamide) microgels crosslinked with the plant‐derived polyphenol TA or BIS are used. [ABSTRACT FROM AUTHOR]

Many countries have recently banned the production and importation of petrochemical plastic microbeads for use as exfoliating agents in personal care products. Plastic particles in products of this nature are too small to be retrieved during wastewater treatment and they accumulate in the environment, negatively impacting living organisms and ecosystems. Sustainable alternatives that offer comparable mechanical properties to synthetic plastic microbeads could be developed using biowaste material. Brewer's spent grain (BSG), the primary residue of the brewery industry, is shown herein to be a promising starting material in the development of biodegradable, nontoxic microbeads. After dilute acid hydrolysis, pretreated lignocellulosic pulp from BSG is solubilized using an aqueous system of NaOH and ZnO. Solid microbeads may then be formed by dropping the resulting solution into an acid bath, filtering, and drying. The conditions of each step required optimization to successfully produce spherical microbeads with a mean diameter as small as 1.25 mm, a homogeneous size distribution, and an average hardness of 199 MPa. The beads also demonstrated superior cleansing abilities to commercially available natural exfoliating particles. BSG microbeads are therefore a promising option for use as a physical exfoliating agent in various personal hygiene products. [ABSTRACT FROM AUTHOR]

With the development of high power‐density electronic devices on smaller scales and emerging new energy vehicles, high thermal conductive materials have attracted more attention for better thermal management to adapt to various applications. By combining both the advantages of polymer materials and thermally conductive fillers, thermal conductive polymer composite materials are widely used in packaging and the protection of electronic devices for their mechanical robustness, high thermal conductivity, excellent insulation properties, heat resistance, and chemical resistance. In this review, first, the basic theory of heat conduction of polymer composites is discussed. Second, according to the classification of the composition of the thermal conductive polymer, the filled thermal conductive material is emphatically introduced. In this paper, the construction process of a thermal conductive network of polymer and composites is discussed from the perspective of processing. The simple construction of a thermal conductive network includes core‐shell structure, external force orientation, electrostatic spinning, electrostatic spraying, induced orientation, and vacuum‐assisted filtration. The three‐dimensional thermal conductivity network can be constructed using self‐assembly and template methods. From the above processing methods, this paper analyzes how to effectively improve thermal conductivity and achieve the goal of high thermal conductivity and excellent mechanical properties under low filling. After that, the contribution of filler and polymer modification to thermal conductivity is explained in detail. Finally, the future research direction of functionalization is prospected. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate that blending an organic dye (guest/filler), with a vinyl polymer (host template), is an inexpensive and simple approach for the fabrication of multifunctional photonic materials which could display an enhancement in the desirable properties of the constituent materials and, at the same time provide novel synergistic properties for the guest-host system. A new guest-host nanocomposite system comprising Phenol Red dye and poly (vinyl alcohol) as guest and host template, respectively, which exhibits tunable optical characteristics and saturable absorption behavior, is introduced. The dependence of local electronic environment provided by the polymer template and the interactions of the polymer molecules with the encapsulated guest molecules on the observed optical/nonlinear absorption behavior is discussed. An understanding of the tunability of the optical/ photophysical processes, with respect to the filler content, as discussed herein could help in the design of improved optical materials for several photonic device applications like organic light emitting diodes and saturable absorbers. [ABSTRACT FROM AUTHOR]

The dissociation of polaron pairs into free charge carriers in organic bulk heterojunction solar cells is a fundamental step in generating photocurrent and is still in debate. In this study, we propose two simple criteria that can be used to test the validity of any polaron pair dissociation model for polymer-fullerene bulk heterojunction solar cells. The first criterion states that the ratio of the bimolecular recombination current density to the maximum photocurrent density should increase as a function of applied voltage. The second criterion states that the ratio of the bimolecular recombination current density to the maximum photocurrent density at short circuit should not be larger than 1. We apply these criteria to test the validity of the widely used Onsager-Braun model by using the experimental current-voltage data of poly[2-methoxy-5-(3'-7'-dimethyloctyloxy)-p-phenylene vinylene] (OC1C10-PPV) and [6,6]-phenyl C61-butyric acid methylester (PCBM) based solar cells. We find that our numerical analysis is not suitable to employ these criteria. Our analytical analysis, on the other hand, clearly demonstrates that the Onsager-Braun model simply cannot fulfill the first criteria. The reason is because the polaron pair dissociation given by the Onsager- Braun model is too strongly influenced by the electric field (i.e., decreases too rapidly as the electric field decreases). The analysis provides a further evidence against the widely used Onsager- Braun model. The proposed criteria can help us to determine the correct model for polaron pair dissociation by serving as a guideline on how strongly the electric field is allowed to influence the polaron pair dissociation. [ABSTRACT FROM AUTHOR]

In this report, an attempt has been made to investigate the morphological evolution of nanoscale surface ripples on aliphatic (polypropylene, PP) and aromatic (polyethylene terephthalate, PET) polymeric substrates irradiated with 50 keV Ar+ ions. The specimens were sputtered at off normal incidence of 30° with 5 x 1016 Ar+ cm-2. The topographical features and structural behavior of the specimens were studied using Atomic Force Microscopy (AFM) and UV-Visible spectroscopy techniques, respectively. The Stopping and Range of Ions in Matter simulations were performed to calculate sputtering yield of irradiated PP and PET polymers. Sputtering yield of carbon atoms has been found to be smaller for PP (0.40) as compared to PET (0.73), which is attributed to the different structures of two polymers. AFM analysis demonstrates the evolution of ripple like features with amplitude (2.50 nm) and wavelength (690 nm) on PET while that of lower amplitude (1.50 nm) and higher wavelength (980 nm) on PP specimen. The disorder parameter (Urbach energy) has been found to increase significantly from 0.30 eV to 1.67 eV in case of PP as compared to a lesser increase from 0.35 eV to 0.72 eV in case of PET as revealed by UV-Visible characterization. A mutual correlation between ion beam sputtering induced topographical variations with that of enhancement in the disorder parameter of the specimens has been discussed. [ABSTRACT FROM AUTHOR]

The forced translocation of homopolymers through αβα sandwich-like compound channels was investigated by Monte Carlo simulation. The interaction between polymer and part α is strongly attractive, whereas that between polymer and part β is purely repulsive. Simulation results show that the translocation is influenced obviously by the length of part β (Lβ) and the starting position of part β (Lα1). For small Lβ, the translocation is mainly governed by the escaping process, and polymer is trapped near the exit of the channel. However, the translocation time can be tuned by varying Lα1 and the fastest translocation can be achieved at relatively large Lα1. Whereas for large Lβ and small Lα1, the translocation is mainly controlled by the filling process. It is difficult for polymer to enter the channel, and polymer is trapped at the first αβ interface. Finally, the dynamics for the filling process and the escaping process are discussed from the view of free-energy landscape, respectively. [ABSTRACT FROM AUTHOR]

Reconfigurable metamaterials have great potential to alleviate complications involved in using passive metamaterials to realize emerging electromagnetic functions, such as dynamical filtering, sensing, and cloaking. This paper presents a new type of tunable meta-atoms in the X-band frequency range (8-12 GHz) toward reconfigurable metamaterials. The meta-atom is made of all flexible materials compliant to the surface of an interaction object. It uses a liquid metal-based split-ring resonator as its core constituent embedded in a highly flexible elastomer. We demonstrate that simple mechanical stretching of the meta-atom can lead to the great flexibility in reconfiguring its resonance frequency continuously over more than 70% of the X-band frequency range. The presented meta-atom technique provides a simple approach to dynamically tune response characteristics of metamaterials over a broad frequency range. [ABSTRACT FROM AUTHOR]

The cover image is based on the Research Article Biosourced spherical microbeads from brewer's spent grain for sustainable personal hygiene products by Amy McMackin et al., https://doi.org/10.1002/pol.20230613 Microbeads used in personal hygiene products have conventionally been crafted from synthetic plastics offering precise control over hardness and shape. However, the disposable nature of these products has linked synthetic plastic microbeads to pollution in marine environments. In this study, we present a sustainable alternative by using brewer's spent grain as our starting material. Through solubilization and regeneration, we transform this brewery residue into spherical lignocellulosic microbeads. Beyond mitigating the environmental impact associated with exfoliating microbeads in personal care items, this method introduces an innovative valorization strategy for brewer's spent grain. Image design by Amy McMackin via Canva.com. [ABSTRACT FROM AUTHOR]

This article aims to describe the implementation, evaluation, and outcomes associated with a science, technology, engineering, and mathematics (STEM) research fellow experience at an historically Black college and university (HBCU) funded by the National Science Foundation. This experience, Polymer Research, was part of a multipronged approach for infusing polymers into the General and Physical Chemistry curricula. After briefly reviewing the literature on broadening participation in STEM and undergraduate research experiences, the authors provide a description of the context, evaluation, and project outcomes and conclude with a discussion on project impact and the role of HBCUs in training and graduating underrepresented students in STEM. [ABSTRACT FROM AUTHOR]

Five coordination polymers, namely, [Cd(µ 3 –5-nip)(µ-obix)] n ( 1 ), [Co(µ 3 –5-nip)(µ-obix)] n ( 2 ), [Zn(µ−5-nip)(µ-obix)] n ( 3 and 4 ) and [Cd(µ−5-nip)(µ-bisobix)] n ( 5 ) (5-nip: 5-nitroisophthalate, obix: 1,2-bis(imidazol-1ylmethyl)benzene, bisobix: 1,2-bis(2-isopropylimidazol-1ylmethyl)benzene) were hydrothermally synthesized and characterized by IR spectroscopy, elemental analysis, single crystal and powder X-ray diffraction and thermal analysis (TG/DTA). X-ray results showed that the complexes displayed structural diversity depending on metal ions and conformations of bis(imidazole) linkers. Complexes 1 and 2 were 1D structures and obix ligand displayed cis -conformation. Complexes 3 and 4 exhibited 2D and 3D structures with same components depending on obix conformation. In complex 5 , 3D+3D→3D interpenetrated structure was obtained with dia topology when bisobix having sterically hindered groups on imidazole rings was used. Moreover, thermal, photoluminescence and optical properties of the complexes were also investigated. [ABSTRACT FROM AUTHOR]

A novel framework based on stochastic modeling methods and likelihood analysis to address large‐scale monetization processes of converting shale gas to polymers under the mixed uncertainties of feedstock compositions, estimated ultimate recovery, and economic parameters is presented. A new stochastic data processing strategy is developed to quantify the feedstock variability through generating the appropriate number of scenarios. This strategy includes the Kriging‐based surrogate model, sample average approximation, and the integrated decline‐stimulate analysis curve. The feedstock variability is then propagated through performing a detailed techno‐economic modeling method on distributed‐centralized conversion network systems. Uncertain economic parameters are incorporated into the stochastic model to estimate the maximum likelihood of performance objectives. The proposed strategy and models are illustrated in four case studies with different plant locations and pathway designs. The results highlight the benefits of the hybrid pathway as it is more amenable to reducing the economic risk of the projects. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2017–2036, 2018 [ABSTRACT FROM AUTHOR]

Five photoresponsive polymers towards ultraviolet (UV), visible, and near-infrared (NIR) light were prepared and assembled to achieve complicated light-induced shape deformation. The UV light responsive polymer was contributed by a synthesized linear polyurethane elastomer (azo-PU) containing azobenzene groups in the main chains, which presented both shape-memory effect and UV light-induced shape deformation behavior. The other four polymers that were sensitive to visible or NIR light consisted of crosslinked poly(ethylene-co-vinyl acetate) (EVA) composites mixing with gold nanoparticles (AuNPs), Nd(TTA) 3 Phen, Yb(TTA) 3 Phen, and Sm(TTA) 3 Phen as photothermal fillers, respectively. The results showed that the shape recoveries of these EVA composites were triggered merely by visible and/or NIR light with suitable wavelengths. Moreover, the assembly of the prepared five light-induced polymers in three different manners improved the spatiotemporal control of complicated shape deformations upon different light illumination sequences. Benefiting from the creation and assembly of five photoresponsive polymers with high wavelength selectivities, complex shapes of polymer specimens can be achieved in a remote and non-contact manner via simply tuning irradiation sequences. The reported materials here and their assembly manners provide a strategy to expand the applications of photoresponsive polymers. [ABSTRACT FROM AUTHOR]

ABSTRACT To further enhance oil recovery of high temperature and high salinity reservoir at Tahe Oilfield, field test results from profile control and oil displacement of gel were carried out in this article. Static and dynamic evaluations were performed through gel strength code method, environment scanning electron microscope, and physical simulation experiment devices. The field test results show that, under the conditions of high temperature (100.8 °C) and salinity (19.8 × 104 mg/L), the stable gel system was formed with gelling time range from 26 to 45 h, gel strength ranging from E to H, and dehydrating amount lower than 3.0% after ageing 60 days. Meanwhile, the microstructure is very stable. When the permeability and gel strength ranges from 0.212 to 0.970 μm2 and E to H, respectively, the plugging ratio is larger than 85%, and the plugging performance becomes better with the increase of permeability or gel strength. Due to the profile improvement rate of 99.8% and the oil recovery up to 28.5%, profile control and oil displacement technology of gel can effectively promote fluid diverting. The water cut reduced from 95.2% to 89.0% during field test carried out in Tahe Oilfield, which means that profile control and oil displacement technology of gel could stabilize oil production by water control effectively. Also, this technology has a wide application prospective that provides with strong technical support for further enhanced oil recovery in high temperature and high salinity reservoirs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46075. [ABSTRACT FROM AUTHOR]

Abstract: Performance stability of electrochemically active polymers (EAPs) remains one of the greatest and long‐standing challenges with regard to EAP‐based technologies for a myriad of energy, biomedical, and environmental applications. The performance instability of EAPs originates from their structural alteration under repeated charge–discharge cycling and/or flexing. In this work, a conceptually new “soft confinement” strategy to enhance EAP performance stability, including cyclic and mechanical, by using rationally designed, vapor‐deposited organic networks is presented. These chemically cross‐linked networks, when in contact with an electrolyte solution, turn into ultrathin, elastic hydrogel coatings that encapsulate conformally the EAP micro‐/nanostructures. Such hydrogel coatings allow easy passage of ions that intercalate with EAPs, while simultaneously mitigating the structural pulverization of the EAPs and/or their detachment from substrates. Fundamentally distinct from extensively studied “scaffolding” or “synthetic” approaches to stabilizing EAPs, this soft confinement strategy relies on a postmodification step completely decoupled from the EAP synthesis/fabrication, and enjoys the unique advantage of substrate‐independency. Hence, this strategy is broadly applicable to various types of EAPs. The proposed stability enhancement strategy is demonstrated to be effective for a range of EAP systems with differing chemical and morphological characteristics under various testing conditions (repeated charging/discharging, bending, and twisting). [ABSTRACT FROM AUTHOR]

Performance of polymer reinforced with continuous long natural and man-made fibers was extensively investigated in literature. However, using yarns made of short discrete natural fibers needs to be investigated as a source of sustainable reinforcement for composites. In this study, long yarns made of short flax and jute fibers were selected to reinforce polyester bars. Infusion technique was implemented to produce natural yarns reinforced polyester (NYRP) bars having various fiber volume fraction ratios. Microscopic images showed good fibers distribution and resin-fibers impregnation across the of NYRP bars. In addition, polyester bars reinforced with selected natural yarns lead to remarkable enhancement of their tensile strength, stiffness and ductility. Moreover, concrete slabs reinforced with surface treated NYRP bars performed compatibly until failure. Despite low stiffness of the produced NYRP bars, their use for reinforcing normal and lightweight concrete slabs enhanced their ductility and toughness as well as increased their flexural capacity up to six-fold. [ABSTRACT FROM AUTHOR]

The ability to switch between thermally and photochemically activated reaction channels with an external stimulus constitutes a key frontier within the realm of chemical reaction control. Here, we demonstrate that the reactivity of triazolinediones, powerful coupling agents in biomedical and polymer research, can be effectively modulated by an external photonic field. Specifically, we show that their visible light-induced photopolymerization leads to a quantitative photodeactivation, thereby providing a well-defined off-switch of their thermal reactivity. Based on this photodeactivation, we pioneer a reaction manifold using light as a gate to switch between a UV-induced Diels-Alder reaction with photocaged dienes and a thermal addition reaction with alkenes. Critically, the modulation of the reactivity by light is reversible and the individually addressable reaction pathways can be repeatedly accessed. Our approach thus enables a step change in photochemically controlled reactivity, not only in small molecule ligations, yet importantly in controlled surface and photoresist design. [ABSTRACT FROM AUTHOR]

A recently developed technique of Micro-Spatially Offset Raman Spectroscopy (micro-SORS) extends the applicability of Raman spectroscopy to probing thin, highly diffusely scattering layers such as stratified paint samples, enabling their nondestructive chemical characterization. The technique has a wide applicability across areas such as cultural heritage, polymer research, forensics, and biological fields; however, currently, it suffers from a major unaddressed issue related to its ineffectiveness with highly heterogeneous samples. In this paper, we address this unmet need while demonstrating an effective strategy to probe such samples, involving a mapping on scales substantially larger than the scale of heterogeneity. This approach provides an effective means of obtaining robust and representative micro-SORS datasets from which sample composition can be effectively deduced, even in these extreme scenarios. The approach is compared with a basic point collection approach on two-layer paint systems where different layers--top, bottom, or both--are heterogeneous. The study has particular relevance to cultural heritage, where heterogeneous layers are often encountered with painted stratigraphies. [ABSTRACT FROM AUTHOR]

Polymeric foams derived from renewable sources are a requirement of the modern world due to increasing concern about the environment and various issues related to petroleum based foams. Much research has been conducted recently to produce foams using renewable sources; however, low mechanical strength, high flammability and low thermal stability are a matter of concern when using these foams on a commercial scale. Various approaches may be used to overcome these problems, including the modification of raw material or the incorporation of property-enhancing fillers, with or without surface treatment. In this overview, various methods that may be used to enhance mechanical, thermal and flame retardant properties of renewable source-based and other environmentally benign polyurethane foams are discussed. [ABSTRACT FROM AUTHOR]

Viscosity remedial technology, which uses a water-soluble polymer mixed with remedial fluids, has been introduced in recent years to improve the removal efficacy of perchloroethylene/tetrachloroethylene (PCE) by improving oxidant coverage (i.e. sweep efficiency). Xanthan gum and hydrolysed polyacrylamide (HPAM) are relatively stable with time and temperature and possess salt and oxidation resistance, indicating that they may be good flooding agents (the former is better than the latter in this work). In this work, we quantified the polymer directly improved oxidation of PCE during transport by using a two-dimensional flow tank. Using a low pore volume (≤3.0), the removal rate of the PCE increased with the polymer concentration before stabilizing at approximately 93.00 and 88.30% for xanthan and HPAM, respectively. In this work, over 80% of PCE was removed via less than 3.0 PV of the SDS solution, whereas complete removal (100%) was achieved with less than 3.0 PV of SDS foam. Furthermore, the new experimental discoveries demonstrate that xanthan is better than HPAM and SDS foam is a better remediation agent than the SDS solution for removing PCE. [ABSTRACT FROM AUTHOR]

Revealing the nature of chain packing in conjugated polymer nanoparticles (CPNs) is one of the important issues to polymer physics research. Surfactant-stabilized CPNs in water show significantly enhanced luminescence intensity in comparison to small molecular organic dyes and single polymer chains dissolved in solvents. The importance of the conjugated polymer structure in nanomaterials is undoubted. However, details of the relationship between alignment of conjugated polymer backbone in CPNs and its luminescent property have not been established. Furthermore, there are yet no methods that can predict the atom-resolved structure of conjugated polymer in the CPNs. Herein, we employ coarse-grained (CG) molecular dynamic simulations to investigate the structure of phase-separated film and the film shattering process for a mixture of poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and 1,2-dioctanoyl-sn-glycero-3-phosphocholine (D8PC). The p-p stacked structure of PCPDTBT is significantly enhanced when the ratio of D8PC increases in both dried and water exposed film. We also show that the amount of D8PC is at least 2.5 times larger than that of PCPDTBT to wrap the conjugated polymer chain, and the direct retrieval of atomistic details is achieved through back-mapping from the morphology of CG. Finally, we confirmed that conjugated backbones inside the nanoparticles were completely shielded from the aqueous solution by the dense layers of alkyl chains, resulting in remarkably enhanced chain packing. These simulated results are correlated with experimentally observed structure through UV-vis-near-infrared (UV-vis-NIR) spectrometry, scanning electron microscopy (SEM), particle size analyzer (PSA), transmission electron microscopy (TEM), and grazing-incidence X-ray diffraction (GIXD). [ABSTRACT FROM AUTHOR]

Super absorbent polymers (SAPs) are novel multipurpose materials in concrete technology. This study investigated the potential for using SAPs as a mechanism for physical air entrainment. Mixtures were produced using various quantities of either dry or pre-saturated SAP along with a conventionally air-entrained control. One additional mixture used lightweight fine aggregate as a mechanism for physical air entrainment. The quality of the air void system was investigated using a high resolution flatbed scanning and image analysis. It was found that one-dimensional water absorption decreased with increased SAP dosage suggesting that SAP would not increase degree of saturation during freezing and thawing. Various dosage rates and conditions of SAP were able to produce adequate air void systems with satisfactory size and distribution as compared to conventional air entraining agents. [ABSTRACT FROM AUTHOR]

Cyclic polymers are an important class of macromolecules, but the structural diversity of the backbone is limited. Herein we report the use of the Piers-Rubinsztajn reaction for the one-step synthesis of cyclic polysiloxanes with novel structural features. Specifically, the B(C6F5)3-catalyzed coupling of various organic tris(dimethylsiloxy)silane and trialkoxysilane compounds generated a series of cyclic polysiloxanes with cyclotetrasiloxane subunits. The thiolated cyclic polymers were also shown to be effective in directing the circular assembly gold nanoparticles. The presence of constrained rings in the backbone is unprecedented and may offer opportunities for novel applications of these cyclic polymers. [ABSTRACT FROM AUTHOR]

Polymer brushes have become a significant focus of polymer research with the need for straightforward and versatile surface modification. With the development of controlled radical polymerization from surfaces, new theoretical models, and sophisticated characterization tools, the resulting ability to control brush density and brush thickness gives unparalleled control over surface properties and functionality. By increasing brush density, a stretched brush conformation is formed as a result of constraining the cross-sectional area of that brush strand which thereby influences the interactions of molecules with the brush surface. The associated residual stress also gives polymer brushes properties distinct from an equivalent layer of coated polymer chains. Examples of uncharged and charged “grown from” polymer brushes, the effect of architecture on physical behavior, and the influence of nanoscale patterning will be described. The use of brush surfaces in biology relevant applications will be discussed and include resistance to nonspecific binding, cell bioadhesion, their use as platforms for biosensors, thermoresponsive surfaces, and targeted protein binding. [ABSTRACT FROM AUTHOR]

A series of experiments were carried out to investigate polymer recovery in the micro hot embossing process. Above the glass transition temperature ( Tg ), polymer deformation becomes much easier and complete filling of microcavities is generally not difficult to achieve. One of the problems restricting replication efficiency of the hot embossing technique is polymer recovery. After complete filling, if without timely cooling, large recovery may happen and lead to defective embossing results. In this study, the recovery was found to be able to cause a height reduction of 21.4%, 17.8%, and 16.0% in the hot embossed micro-pyramid arrays, micro-pillar arrays, and micro-prism arrays respectively. This recovery can be avoided by means of prolonging embossing time or increasing embossing temperature. However, prolonging embossing time increases cycle time, while increasing embossing temperature is likely to induce severe warpage or damage problems. Thus, improvement of the embossing process is in urgent need. Through investigation on the recovery phenomena, which are characterized by that an apparent height and shape difference can be observed among adjacent embossed structures in the same polymer replica, it was found that interfacial bonding formed between the mold cavity wall and the polymer material is capable of preventing the recovery from happening. By applying the energy balanced approach widely used in fracture mechanics to the polymer recovery process, a theory of competition between the recovery and the adhesion was proposed, with which the experimental phenomena can be satisfactorily explained. During unloading, if the strain energy stored in the system for recovery is not enough for breaking the interfacial bonding, the recovery will be stopped; otherwise, large recovery may happen. To verify the theory, hot embossing experiments considering effects of process conditions and improved adhesion were conducted finally, further demonstrating that in the micrometer scale the adhesion has significant impacts on the recovery behavior of the polymer. Results of this research work indicate that we can take advantage of the adhesion to prevent the recovery and to achieve high-accuracy and high-efficiency micro hot embossing in the temperature range near the Tg . [ABSTRACT FROM AUTHOR]

Surface-degrading polymers have been widely used to fabricate scaffolds with the mechanical properties appropriate for tissue regeneration/repair. During their surface degradation, the material properties of polymers remain approximately unchanged, but the scaffold geometry and thus mechanical properties vary with time. This paper presents a novel method to determine the time-dependent mechanical properties, particularly stiffness, of scaffolds from the geometric changes captured by synchrotron-based imaging, with the help of finite element analysis (FEA). Three-dimensional (3D) tissue scaffolds were fabricated from surface-degrading polymers, and during their degradation, the tissue scaffolds were imaged via the synchrotron-based imaging to characterize their changing geometry. On this basis, the stiffness behavior of scaffolds was estimated from the FEA, and the results obtained were compared to the direct measurements of scaffold stiffness from the load-displacement material testing. The comparison illustrates that the Young's moduli estimated from the FEA and characterized geometry are in agreement with the ones of direct measurements. The developed method of estimating the mechanical behavior was also demonstrated effective with a nondegrading scaffold that displays the nonlinear stress-strain behavior. The in vivo monitoring of Young's modulus by morphology characterization also suggests the feasibility of characterizing experimentally the difference between in vivo and in vitro surface degradation of tissue engineering constructs. [ABSTRACT FROM AUTHOR]

The article offers information on the independent not-for-profit research corporation Polymer Processing Institute (PPI) focusing in areas of polymer processing. It mentions availability of instrumented machine with experimental molds and visualization capability in injection molding. It also highlights research capabilities of PPI such as tandem extruders set-up for low-density foams.

The crystallization behavior of poly(ε-caprolactone) (PCL) in a poly(vinylidene fluoride) (PVDF)/PCL blend as well as on a highly orientated PVDF substrate was studied by means of POM, DSC and TEM. The results show that the miscibility of the PVDF/PCL blend and the spherulitic morphology of PVDF varies with the blend ratio. For all the compositions, the pre-existing PVDF crystals accelerated the crystallization of PCL because the PVDF exhibits very strong nucleation ability toward PCL as reflected by the occurrence of heteroepitaxy and the transcrystallization of PBA on the PVDF substrate. This is associated with the perfect lattice matching between the PBA and PVDF crystals. [ABSTRACT FROM AUTHOR]