The 50 most-cited articles in Journal of Applied Polymer Science, 2021

Abstract Silicone is a synthetic polymer widely used in the biomedical industry as implantable devices since 1940, owing to its excellent mechanical properties and biocompatibility. Silicone biomaterials are renowned for their biocompatibility due to their inert nature and hydrophobic surface. A timeline illustration shows critical development periods of using silicone in varied biomedical applications. In this review, silicone properties are discussed along with several biomedical applications, including medical inserts, speciality contact lenses, drains and shunts, urinary catheters, reconstructive gel fillers, craniofacial prosthesis, nerve conduits, and metatarsophalangeal joint implants. Silicones are prone to microbial infections when exposed and interactions with the host tissue. As in the case of medical inserts, the development of specific antimicrobial strategies is essential. The review highlights silicone implants' interaction with soft and bone tissue and various antimicrobial strategies, including surface coating, physical or chemical modifications, treating with…

Abstract The use of polymer foams is becoming increasingly important due to the attainable weight reduction and value‐added properties. The development of foam structures is a popular research area as they have outstanding energy absorbing capability, which is related to the special deformation mechanisms of the cell structure (cell wall buckling and collapse of the cells). This property is exploited by the sports industry, where the main task of such products is to protect the health of the athlete and to ensure safe sports conditions. This review provides a comprehensive presentation of the advanced energy absorbing applications of polymeric foams in sports. The article presents in detail the processing technologies of polymer foams, as well as the sports‐specific regulations which contain the requirements for sports products. The impact damping of polymeric foams is typically determined by falling weight impact tests, which were used in several previous studies. However, it is a great challenge to compare the published results, as the test parameters and the tested materials are…

Abstract Most of the ancient buildings are made of inflammable wooden structures, which have serious potential safety hazards. Applying fire‐retardant coating is one of the simplest and most effective means of fire prevention in ancient wooden buildings. In this work, we have demonstrated that the Ti 3 C 2 T x transition metal carbide/carbonitride (MXene) was applied as the synergetic agent, waterborne epoxy resin as the film‐forming agent, ammonium polyphosphate, dipentaerythritol, and melamine (P‐C‐N system) as the intumescent fire‐retardant system to prepare Ti 3 C 2 T x /epoxy intumescent fire‐retardant coating (TEIFC). The results showed that MXene has significantly improved the fire‐retardant performance of the coating. By incorporating 3 wt% Ti 3 C 2 T x (TEIFC‐3, with 62 wt% P‐C‐N system), the coating displayed UL‐94 V‐0 rating with the limiting oxygen index value of 38%. In addition, the combination of Ti 3 C 2 T x and P‐C‐N system enhanced the Shore hardness of the coating to 95 SHD (TEIFC‐3). Furthermore, TEIFC‐3 presented high thermal stability with the T HRI of 177.0°C…

Abstract Lignin functions as an essential polymer in plants that forms the plant body's structural framework. The natural glue holds the cellulosic fibers together in the plant body, thereby providing rigidity and strength. Despite this, lignin shows promising relevance for biomaterial production due to its abundance, nontoxic nature and biodegradability. Considerably, adhesive components were derived from petroleum, which is increasingly more expensive. Hence, lignin, the natural glue in plant materials, gained much popularity because of its phenolic nature, making it an attractive substitute for adhesives. Lignin‐based binders are produced through phenols substitution in phenol‐formaldehyde resins with lignin due to their similar structural framework. Many researchers have confirmed the multifunctional applications of lignin, such as wood adhesive in fiber board, plywood and particleboard, a binder in printed wiring boards, abrasive tools, epoxy asphalts, epoxy wood composites, 3D printing, adhesive hydrogels, soil suppressants, lignocellulosic paper and coatings. This review…

Abstract Biopolymeric chitosan is considered a promising encapsulating agent for textile applications due to its biocompatibility, lack of toxicity, antibacterial activity, high availability, and low cost. After cellulose, it is nature's most important organic compound. Also, chitosan has unique chemical properties due to its cationic charge in solution. Microencapsulation technologies play an important role in protecting the trapped material and in the durability of the effect, controlling the release rate. The application of chitosan microcapsules in textiles follows the current interest of industries in functionalization technologies that give different properties to products, such as aroma finish, insect repellency, antimicrobial activity, and thermal comfort. In this sense, methods of coacervation, ionic gelation, and LBL are presented for the production of chitosan‐based microcapsules and methods of textile finishing that incorporate them are presented, bath exhaustion, filling, dry drying cure, spraying, immersion, and grafting chemical. Finally, current trends in the textile…

Abstract Shape memory polymers (SMPs) are polymers which ''remember'' their original shape and can return to it after deformation, if an external stimulus—often an increased temperature – is applied. Some SMPs can be 3D printed, typically by fused deposition modeling (FDM). The most well‐known SMP is poly(lactic acid), which belongs to the most often used materials in FDM 3D printing. There are; however, many more SMPs which can be 3D printed to combine the possibilities to prepare new, sophisticated shapes with the opportunity to restore these shapes after undesirable or intentional deformation. This review gives an overview of several 3D printable SMPs, their mechanical characteristics and their possible applications.

Abstract Polyethyleneimine (PEI) is a common polymer used in many industrial applications and in research, especially in surface chemistry. It is available in a wide range of molecular weights and different degrees of branching. It is classified as linear or branched and sometimes the term hyperbranched is also used. This description, however, is quite rough, which limits the possibility to correlate the structure of the PEI to its properties. The aim of this study is to provide analytical tools to characterize the polymer at a level of detail not normally provided by the supplier of PEI. To this end, five commercially available polyethyleneimines were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and nuclear magnetic resonance spectroscopy to gain insight into the structure and the functional groups present in the polymers. Quantitative 13 C NMR analysis turned out to be particularly useful, revealing the degree of branching of the polymer based on the ratio of primary, secondary, and tertiary amino groups.

Abstract Conductive hydrogels with high flexibility, superior formability, good mechanical elasticity, and excellent biocompatibility have emerged as promising materials for broad applications in flexible/wearable electronic devices. In this work, a conductive dual‐network PVA/SA/MXene hydrogel (PSM‐h) composed of polyvinyl alcohol, sodium alginate, and MXene (Ti3C2Tx) is constructed by a green method without using chemical crosslinking agents. The resultant hydrogel with dual‐network feature shows excellent cytocompatibility (no toxicity for human umbilical cord mesenchymal stem cells), high stretchability (up to 263%), and superior anti‐fatigue ability (stretched up to 1000 cycles). More importantly, PSM‐h based strain sensor presents good sensing sensitivity with a fast response time (62.5 ms) and a low detection limit even under a very slight strain of 0.2%. In terms of the practical application, the PSM‐h based strain sensor can be applied to detect and distinguish various human motions.

Abstract Owing to economic and environmental benefits, new generations of materials/commodities follow “from waste to wealth” strategy. Recently, there has been a huge upsurge in research on the development of eco‐composites using recycled plastic polymers and agro‐residues because the eco‐composites satisfy the stringent environment regulations and are cost‐effective. Herein, we present a detailed review on the potential use of several types of natural fillers as an efficient reinforcement for recycled plastic polymers. In particular, the characterization of different categories of eco‐composites according to their morphological, physical, thermal, and mechanical properties is extensively reviewed and their results are analyzed, compared, and highlighted. Furthermore, a framework to produce functional eco‐composites, which includes functionalization of ingredients, critical issues on microstructural parameters, processing, and fabrication methods, is outlined and supported with sufficient data from the literature. Finally, the review outlines the emerging challenges and future…

Abstract The searching of suitable alternatives to petroleum‐based fillers is an uncompromising challenge in present day rubber research. Recently, natural fibers are the part of great attention of both academic and industrial researchers due to their easy availability, environmental friendliness, and biodegradability. Natural fiber is cellulose‐rich material, which is preferentially used as alternative filler in rubber technology. This article reviews current advances in natural fibers filled rubber composites in terms of mechanical, thermal, and biodegradable properties (2010–2020). The incorporation of unmodified natural fibers as filler is not able to offer desired reinforcement in rubber composites. Several surface modification methods can be introduced to improve the overall performances of natural fibers filled rubber composites. Finally, the review clarifies present status and future prospects of natural fibers based advanced rubber composites in automobile industry. The successful designing of natural fibers based sustainable rubber composites can introduce a new era in…

Abstract Natural bio‐based materials used in wound dressings have been continuously developed in recent years, and have certain advantages in water retention, biocompatibility, and therapeutic properties. Konjac glucomannan (KGM) is a kind of plant polysaccharide with good cell compatibility and gel properties. Various gels obtained by modification of KGM through physical and chemical methods have great application potential in wound excipients. In the past few years, various KGM‐based wound barrier materials such as hydrogels, xerogel, microspheres, films, and fibers have been continuously researched and developed. The combination of KGM and other polymers can improve the problem of poor mechanical properties and give it new functional properties, which is beneficial to the moisturizing of the wound surface and the release of drugs to promote wound healing. This article reviews the physicochemical properties of KGM and the latest developments in KGM‐based composite gels, reveals the relationship between molecules in KGM‐based composite gels, and looks forward to the research and…

Abstract Fused filament fabrication (FFF) has been used to create prototypes and functional parts for various applications using plastic filaments. It has also been extended to the use of continuous fibers for reinforcing thermoplastic polymers. This study aims to optimize the deposition design of a coextruded continuous carbon fiber (CCF) composite filament with a polyethylene terephthalate glycol‐modified (PETG) filament. The characterizations on the raw materials revealed that the matrix polymer in CCF composite filament had similar physicochemical properties as PETG, and carbon fibers were homogeneously distributed in CCF filament. The effect of raster orientation and shells number on the mechanical properties of non‐reinforced and coextruded CCF‐reinforced PETG was investigated. The highest mechanical properties were obtained at a raster orientation of 0° for both reinforced and non‐reinforced materials. With the increase of raster orientation, Young's modulus and ultimate tensile strength decreased. The presence of shells improved the tensile strength of non‐reinforced PETG.…

Abstract Poly(lactic acid) (PLA) stands out as the most promising biodegradable alternative to conventional petrochemical‐based polymers for manufacturing of high‐performance materials applied in medicine, pharmacy, food, textile, and electronic industry. This review was aimed to present the conventional and up‐to‐date technologies for PLA processing including melt blending and molding, hot melt extrusion, 3D printing, foaming, impregnation, thermally induced phase separation, nano‐ and microparticles preparation, wet and dry spinning processes. In addition, the effect of the processing parameters and polymer characteristics on the properties of the final material was elaborated. Diverse possibilities to tailor properties of PLA‐based materials by variation in polymer characteristics and concentration, solvent selection, drying method, processing pressure and temperature, incorporation of bioactive components, and so on were highlighted. The examples of the relations between processing methods, parameters, and end‐product properties are given for a better understanding of all…

Abstract This research reported developing a polyethersulfone (PES) membrane using covalent organic frameworks (COFs) nanoparticle with a mean dimension of 30 nm. The SNW‐1 (Schiff‐based network) COF was synthesized using precursors of melamine and terephthalic acid and then characterized by XRD, SEM, TEM, and FTIR analyses. The influence of different loadings of the COF was evaluated on the permeability, antifouling behavior and dye/salt rejection. The addition of SNW‐1 caused a reduction in surface roughness and an improvement in hydrophilicity of the nanocomposite membranes, which improved their flux and fouling resistance considerably. The improvement of water flux, 2.6 times, was observed by adding 0.5 wt% COF to the membrane matrix. The 0.5 wt% COF membrane presented the best water permeability, 38.9 L/m 2 h bar BSA solution flux, dye rejection of 98.7% for Reactive Green 19 and 62.6% for Reactive yellow 39, 52.9% Na 2 SO 4 and 24.5% NaCl salt rejections. Zeta potential and salt rejection trend indicated a negative surface charge on the nanocomposite membrane. Fouling…

Abstract Thermal degradation of PVC occurs in two stages, with each stage subdivided into two substages. The first refers to the dehydrochlorination, where hydrochloric acid is formed, and giving polyene structures. Hitherto, the degradation mechanism and action of hydrochloric acid as a catalyst during the dehydrochlorination stage are poorly known. Recently, the importance of the tacticity has gained attention for its influence on the dehydrochlorination mechanism. The present work focused on the dehydrochlorination stage, studying the molecular structure by FTIR analysis and the kinetic parameters by TGA analysis in Nitrogen atmosphere, based on three mathematical methods: Friedman, Kissinger, and Flynn‐Wall‐Ozawa. The sample was a pure homopolymer obtained by suspension polymerization. The dehydrochlorination kinetics follows a first order reaction model and occurs by nucleation and growth. The dehydrochlorination begins with the loss of very labile chlorine atoms present in defective and isotactic molecular segments. The formed HCl acts as a catalyst in the degradation.…

Abstract Magnetic chitosan has received considerable attention over the decades due to its low cost, biodegradability, green sources, magnetic intensity. In this review, we reviewed the preparation methods of magnetic chitosan using co‐precipitation, cross‐linking and electrochemical. Therein cross‐linking methodologies involved in the reaction of amino groups are facile to introduce additional reaction groups and improve anti‐swelling of chitosan layers, mostly in an acidic environment. Besides, we focused on the applications of magnetic chitosan in various fields such as wastewater treatment, for example, removal of heavy metal ions, organic/inorganic dyes, fluorides, and pesticides. Moreover, magnetic chitosan also reveals great potential application in the field of medical, pharmaceutical, food and electronic screening. Above all, magnetic chitosan is economically and operationally beneficial as it can be easily separated and controlled with an external magnetic field and can be modified to maximize its functions.

Abstract Hydrogels can be one of the best polymeric wound dressings due to the desirable properties of wound healing. In this study, emphasizing the use of natural biomaterials such as Aloe vera and honey in the structure of cross‐linked polymers, a novel hydrogel was produced that might be applied to healing wounds. In the beginning, four hydrogel groups were made from a combination of Sodium Alginate and Chitosan with Aloe vera extract and honey in optimum concentrations. Then the structure of those was evaluated by SEM and FTIR. After confirming hydrogels' structural properties, their physical properties, including swelling, porosity, density, mass loss, stability, and WVTR, were examined. Besides, the hydrogel biocompatibility was assessed by analyzing the cell viability and hemolytic activity. Adhesion of the cells to the hydrogel was also observed by SEM imaging. The results showed that the designed hydrogel has a porous structure with interconnected cavities, which their size can provide suitable conditions for cell adhesion, migration, and proliferation. Also, their physical…

Abstract Fused deposition modeling (FDM), one among the most commonly used additive manufacturing (AM), techniques has been widely used in recent years to produce customized parts with intricate geometries, especially from thermoplastics. This method was limited in its ability to produce parts for industrial applications due to inferior properties and the poor quality of fabricated parts. Hence, researchers are being driven to discover novel materials that are viable for FDM in order to keep up with enormous demand for functional products. In the recent years, it is widely recognized that the emphasis was placed on the bio‐based polymer composite matrices rather than conventional thermoplastics due to its vital advantages that aid in the replacement of synthetic and perilous materials. On this context, this review focuses on the recent advancements in FDM printing with biomaterials. Specifically, attempts have been made to investigate and provide nutshell of 3D printing of current bio‐based nanocomposites which consist of either bio‐derived filler or polymer matrices in order to…

Abstract The research for self‐healing epoxy vitrimers has attracted a lot of attention over the years. However, due to the special structure of the epoxy molecular chain, which limits its movement ability, epoxy vitrimers usually need to be healed under high temperature and pressure. So it is relatively difficult to healing. Here, a new type of cross‐linked network is obtained by cross‐linking hydrogenated bisphenol A epoxy resin and polypropylene glycol diglycidyl ether (PPGDGE) as hard and soft segments with an amine curing agent containing disulfide bonds. The addition of PPGDGE can improve the mobility of the molecular chains in the cross‐linked network we designed, thereby obtaining a novel epoxy vitrimers with better healing properties. The effect of PPGDGE content on the mechanical properties and self‐healing properties of the material was studied. The ideal sample HEP‐3 has a good tensile strength (33.4 MPa) and a completely broken sample can achieve a good self‐healing rate (71.5%) at 100°C for 3 h without high pressure. In addition, the ideal sample also has excellent…

Abstract Hydrogel system based on enzyme‐mediated mild crosslinking reaction has been a promising approach in tissue engineering. Inspired by skin melanin synthesis and marine mussel adhesion, tyrosinase‐mediated hydrogel crosslinking has been exploited as cell‐friendly reactions and explicit reaction mechanisms. Hydrogel prepared by tyrosinase exhibits appealing properties as a dynamic scaffold for cell delivery and as a bioink for 3D bioprinting. Recapitulating the structure of the native extracellular matrix (ECM), innovative tyrosinase‐mediated hydrogel crosslinking has now shifted to the field of translational medicine. Biomimetic hydrogel with in situ tyrosinase crosslinking can be efficiently and easily applicable to the disease model for therapeutic purposes. In this review, we will discuss a broad range of tyrosinase‐mediated tissue engineering from the specific mechanism of tyrosinase reaction and designing a strategy for tyrosinase‐mediated hydrogel crosslinking to dynamic applications in tissue engineering. In addition, we report the current challenges and future…

Abstract Among commercial biodegradable polyesters, poly(glycolic acid) (PGA) has been rarely investigated for packaging applications, despite its unique advantages such as 100% compostability, high degree of crystallinity, high thermal stability and high gas barrier properties. The application of PGA has been limited by its mechanical brittleness, moisture sensitivity, and high melting temperature (~240°C), restricting its processing and applications for film packaging. In this study, PGA was modified by blending with poly (butylene adipate‐co‐terephthalate) (PBAT) via melt‐extrusion. A commercial terpolymer of ethylene, acrylic ester and glycidyl methacrylate (EMA‐GMA) was selected for compatibilization. The phase morphology, rheology, thermal, mechanical and gas barrier properties of the blends were investigated. With addition of 20 wt. % EMA‐GMA, the elongation of PGA/PBAT (50/50 wt. %) blends was improved from 10.7% to 145%, the oxygen permeability was reduced from 125 to 103 (cm3 mm)/(m2 24 h atm), and the water vapor barrier performance was improved by ~47%. The enhancement…

Abstract Proton exchange membrane fuel cell (PEMFC) is a promising technology that offers a clean and efficient renewable energy source. The hybrid SiO2, sulfonated SiO2(SSiO2), and metal–organic framework‐5 (MOF‐5) incorporated sulfonated poly (ether ether ketone) (SPEEK) ternary composite membranes are fabricated using dry phase inversion technique for PEMFC. The membrane performance is evaluated in terms of water uptake, ion exchange capacity, methanol permeability, and proton conductivity (PC) measurements. The morphological study of fabricated membranes was carried out using scanning electron microscopy and atomic force microscopy analysis. The mechanical stability is strengthened up to 30–40%, and the PC gets enhanced with the incorporation of MOF‐5, achieving simultaneous improvement in proton conduction and membrane stability. The PC of the ternary SPEEK/SSiO2/MOF‐5 membrane is 3.69 × 10−3S cm−1, 32% more than the neat membrane. A significant increase in selectivity of 23% is observed by incorporating SSiO2and MOF‐5 fillers when compared with the neat membrane. The…

Abstract Polysilazane coatings have a broad need in real‐life applications, which require low processing or working temperature. In this work, five commercially available polysilazanes have been spin‐coated on polycarbonate substrates and cured in ambient environment and temperature to obtain transparent, crack‐free, and dense films. The degree of crosslinking is found to have a significant impact on the hardness and Young's modulus of the polysilazane films but has a minor influence on the film thickness and hydrophobicity. Among all five polysilazane coatings, the inorganic perhydropolysilazane‐based coating exhibits the largest hardness (2.05 ± 0.01 GPa) and Young's modulus (10.76 ± 0.03 GPa) after 7 days of curing, while the polyorganosilazane‐derived films exhibit higher hydrophobicity. The molecular structure of polysilazanes plays a key role in mechanical properties and hydrophobicity of the associated films, as well as the adhesion of coatings to substrates, providing an intuitive and reliable way for selecting a suitable polysilazane coating material for a specific…

The global coronavirus disease 2019 (COVID-19) pandemic has rapidly increased the demand for facemasks as a measure to reduce the rapid spread of the pathogen. Throughout the pandemic, some countries such as Italy had a monthly demand of ca. 90 million facemasks. Domestic mask manufacturers are capable of manufacturing 8 million masks each week, although the demand was 40 million per week during March 2020. This dramatic increase has contributed to a spike in the generation of facemask waste. Facemasks are often manufactured with synthetic materials that are non-biodegradable, and their increased usage and improper disposal are raising environmental concerns. Consequently, there is a strong interest for developing biodegradable facemasks made with for example, renewable nanofibres. A range of natural polymer-based nanofibres has been studied for their potential to be used in air filter applications. This review article examines potential natural polymer-based nanofibres along with their filtration and antimicrobial capabilities for developing biodegradable facemask that will promote…

Abstract Harmful electromagnetic radiations that are generated from different electronic devices could be absorbed by a light weight and mechanically flexible good electromagnetic interference (EMI) shielding polymer nanocomposite. On the other hand, different electronic wastes (“e‐wastes”) which are generally polymer building materials generated from wastes of dysfunctional electronic devices are not naturally biodegradable. Our recent effort has been employed to produce bio‐degradable EMI shielding polymer nanocomposite. For that purpose, we had prepared a 50:50 ratio polylactic acid/thermoplastic polyurethane polymer nanocomposite by mixing the conducting carbon black with the blend following the facile and industrially feasible solution mixing method. Morphological characterizations by scanning electron microscopy and transmission electron microscopy analysis revealed the co‐continuous morphology of the neat blend as well as polymer nanocomposites with the preferential distribution of conductive filler on a particular polymer phase. The polymer nanocomposites gave good…

Abstract Environmental concerns about fiber composites are leading manufacturers to consider bio‐based alternatives to petroleum‐derived epoxies. Such a substitution is hindered by a lack of information, so commercially available bio‐based epoxy systems have been compared, their mechanical properties measured, and fiber composites produced by vacuum infusion. Most high bio‐based content resins for infusion use conventional curing agents. Bio‐based content is generally added using Epicerol, but also other bio‐based precursors. A diglycidyl ether of bisphenol A system produced using Epicerol achieves 20 % bio‐based content, but achieves higher contents when Epicerol is used in diluents. Fully bio‐based monomers can be deleterious to the mechanical properties and glass transition temperature (Tg), so are used sparingly. The most‐promising systems (28 % to 43 % bio‐based) compare well to conventional epoxies, possessing good strength, stiffness, toughness, and a reasonableTg. These partially bio‐based epoxies offer an immediate lower‐carbon alternative for vacuum‐infused composites in…

Abstract When fabricating polymer nanocomposites (PNCs), it is difficult for nanoparticles to disperse stably in polymer matrix since their high‐surface energy can cause them to attract each other. In this paper, we review the effects of nanoparticle size, surface chemical properties, and thermodynamic parameters on the dispersion state of nanoparticles (including inorganic and organic particles) in PNCs and describe some key measures to promote the nanoparticles dispersion. The ideal nanoparticles dispersion in polymer melt is available when the particle size is smaller than the rotation radius of polymer chains and the particle surface is highly compatible or has interactions with the matrix. In polymer solution, establishing proper thermodynamic parameters is necessary to ensure the balance interactions among particles, solvents, and polymers, leading to the successful preparation of PNCs with ideal structure. These results could supply theoretical suggestions for the design of PNCs. Moreover, the equilibrium dispersion may be unavailable without reasonable kinetic parameters,…

Abstract Epoxy‐amine thermosetting resins undergo different reactions depending on the amine/epoxy stoichiometric ratio (r). Although many desirable properties can be achieved by varying the stoichiometric ratio, the effects of the variation on the crosslinked structure and mechanical properties and the contribution of these factors to the ductility of materials have not been fully elucidated. This study investigates the brittle‐ductile behavior of epoxies with various stoichiometric ratios and performs curing simulations using molecular dynamics (MD) to evaluate the crosslinked structures. The molecular structure is predominantly branched in low‐stoichiometric ratio samples, whereas the chain extension type structure dominates the high‐stoichiometric ratio samples. As a result, the higher‐stoichiometric ratio samples enhances the ductility of materials and the elongation at break increases form 1.4% (r= 0.6) to 11.4% (r= 1.4). Additionally, the tensile strength (105.4 MPa) and strain energy (7.96 J/cm3) are maximum atr= 0.8 and 1.2, respectively. On the other hand, the Young's…

Abstract This study investigates the influence of using multifunctional epoxy Joncryl ADR 4468 chain extender (CE) on the properties of various polylactide (PLA)/thermoplastic polyurethane (TPU) (75 wt/25 wt) blend systems. The blends were based on two different TPU grades with ether‐ and ester‐based soft segment as the dispersed phase (i.e., TPUether and TPUester) and an amorphous and a semicrystalline PLA grades as the matrix (i.e., aPLA and scPLA). PLA appeared to be more compatible with the TPUester, which caused the enhancement of the impact strength and strain at break values of the blends more remarkably. The dynamic rheological experiments also confirmed that the CE revealed a better reactivity with TPUester than TPUether. This further enhanced the interfacial compatibility between the PLA and TPUester and thereby dramatically improved the impact strength and ductility of the PLA/TPUester blends, specifically those with 0.5 wt% CE. Meanwhile, aPLA as the matrix reflected the TPUs toughening effect more efficiently than scPLA. This was due to the possible shrinkage caused by…

Abstract Genipin‐crosslinked chitosan hydrogels have gained attention as promising drug delivery vehicles. To bring them one step closer to clinical applications, this study evaluates the hydrogels' in vitro biocompatibility and biodegradation. Cytotoxicity test on 3T3 fibroblasts shows that the cells retain normal adhesive properties and high viability on gels with 3.1 and 4.4 m m genipin but not on gels with 1.7 m m genipin. The hydrogels with highest genipin content (4.4 m m ) are studied further in the presence of RAW 264.7 macrophages and DC 2.4 dendritic cells. In both cases, cell viability is preserved and interferon‐β gene transcription is enhanced while over‐production of five inflammatory cytokines is not detected, suggesting the hydrogels' immune stimulating property and potential as vaccine carriers. The biodegradation is monitored efficiently using the hydrogels' intrinsic fluorescence upon crosslinking with genipin. Addition of poly (ethylene glycol) to form a semi‐interpenetrating hydrogel is found to enhance the cytocompatibility to 3T3 cells and delay the…

Abstract The advanced thermal insulation materials with low cost and high mechanical properties play an important role in transport packaging and thermal protection fields. An inorganic/organic composite aerogel was prepared through hydrogen bonds and chemical crosslinking among silica aerogel particles, gelatin (GA), and hydroxyethyl cellulose (HEC). The as‐prepared GA/HEC‐SiO2 composite aerogels were characterized by compression tests, scanning electron microscopy, Fourier transform infrared, thermogravimetric analyzer, and contact angle tests to investigate the chemical composition and physical structure. The GA/HEC‐SiO2 composite aerogels exhibited a strong mechanical strength (0.53–4.01 MPa), a high compression modulus (1.33–11.52 MPa), a lower volume density (0.035–0.081 g/cm3), thermal conductivity as low as 0.035 W/[m K]), a porosity of more than 93%, and hydrophobic angle as high as 150.01° after hydrophobic modification. These results indicate that biopolymer composite aerogels embedded with SiO2 aerogel particles display a bright future in thermal insulation.

Abstract Polyetheretherketone (PEEK) composites exhibit high stiffness, chemical stability, and heat resistance and they are therefore employed in applications under severe operating environments. This work aims to provide insight into the effect of the size, concentration, and type of fillers on the thermal and mechanical properties of PEEK. A total of 32 composites are used to highlight the influence of nature (lamellae, such as boron nitride and graphite and silicon carbide and alumina), size (nano and micrometric), and content (2.5, 5, 7.5, and 10 vol%) of fillers. The melting temperature and lamellar thickness did not change regardless of the nature of the filler. The thermomechanical analysis demonstrates that lamellar fillers form a percolating network and contribute significantly to the enhancement of the storage modulus. The increase in the storage modulus is proportional to the filler content, and it is more pronounced for micro composites. As expected, the percolating network is formed at lower concentrations for lamellar fillers than for spherical ones. The highest…

Abstract Cellulose nanocrystals (CNC) are rod‐like nanoparticles extracted from cellulose. Due to their fascinating properties—renewable, biocompatible, non‐toxic, biodegradable, excellent mechanical performances, high specific surface area, water dispersible, can be assemble in chiral nematic phases—CNC have shown promise in various fields, including oil recovery, polymer composites reinforcing, hydrogels, aerogels, supercapacitors, energy saving buildings, cosmetics, papermaking, coatings, liquid crystals, and waste water treatment. However, the hydrophilic surface of CNC hinders their broader applications. In this context, surface modification of CNC via polymer grafting can be used to finely tune their surficial properties and endow CNC with a variety of functionalities, such as conductivity, pH or temperature responsiveness, reactivity…In particular, surface‐initiated atom transfer radical polymerization (SI‐ATRP) is a powerful tool to graft various polymers with a high grafting density and controlled chain length. In this review, the precise control of grafted polymers from…

Abstract Covalent organic framework (COF) is a new class of porous materials used in energy storage devices. By solvothermal method, the triphenylamine‐based covalent organic framework was synthesized using Schiff base coupling reaction between tris(4‐aminophenyl) amine (TAPA) and tris(4‐formylphenyl) amine. The regular pore structure of TPA‐COFs not only exposes more active sites of triphenylamine structure to electrolyte solution during the charge–discharge process, but also accelerates the transport of ions in the active layer. At the same time, the π‐electron conjugated system and the interlayer π‐π stacking effect effectively promote the conduct of electrons in the two‐dimensional and three‐dimensional directions of COFs materials, which improves the electrochemical performance of the materials. TPA‐COFs show a higher specific capacitance of 263.1 F/g at 0.1 A/g. At the same time, TPA‐COFs materials exhibit a high specific surface area of 398.59 m2/g. After 5000 cycles of charge–discharge, the capacitance retention rate of TPA‐COFs is 111%, showing excellent cycle stability.

Abstract This study was designed to develop a drug delivery system based on poly(N‐isopropylacrylamide) (pNIPAM) hydrogel and a suitable solvent to enhance solubility and local release of curcumin. pNIPAM hydrogel was synthesized by radical polymerization. The chemical, mechanical and physical properties and biocompatibility of pNIPAM hydrogel were investigated as an implantable and rechargeable drug reservoir. Curcumin was loaded within pNIPAM hydrogel during swelling by using two different solvents; methanol, an organic solvent, and low molecular weight polyethylene glycol (PEG200), a polymeric solvent. The results of drug solubility showed that using PEG200 can increase curcumin solubility more than commonly used organic solvents such as methanol. Also, the release profile of drug‐loaded hydrogels demonstrated that PEG200 has a superior effect on the cumulative amount of released curcumin (33.163 ± 0.319 μg/ml) compared to methanol (8.765 ± 0.544 μg/ml) during 1 week. Based on our results, curcumin‐loaded hydrogels did not show any cytotoxicity, and pNIPAM/PEG combination…

Abstract Natural fibers are exceptional renewable resources to develop biocomposite materials for reducing the negative effects on the environment and producing economical and lightweight materials for load bearing semi‐structural applications. The present study is an attempt to develop kenaf/pineapple reinforced bio‐epoxy biocomposite and investigates thermo‐mechanical and viscoelastic properties under accelerated weathering conditions. The compression molding technique is used to develop biocomposite with four different arrangements of kenaf/pineapple laminates. To perform accelerated weathering, laminates are exposed to ultraviolet radiation and humidity conditions with extreme temperature in weathering tester machine. The tensile, flexural, impact, thermogravimetric analysis, thermal conductivity, viscoelastic properties, and water absorption tests are performed before and after accelerated weathering. The results revealed that the hybridization of kenaf/pineapple laminates showed better interfacial strength and stiffness while reducing the moisture sensitivity under accelerated…

Abstract Developing 3D printing high‐performance biodegradable materials is important to protect the environment and deal with emergencies such as COVID‐19. Fused deposition modeling (FDM), one of the 3D printing methods, has many advantages, such as low cost and wide range of materials. However, the weak interlayer adhesion is an important factor restricting the development of FDM. In addition to the influence of material properties, the optimization of 3D printing parameters is also an important means to give full play to the inherent properties of materials. The optimal 3D printing parameters are conducive to the diffusion and entanglement of molecular chains between adjacent layers. PLA/PBAT/PLA‐g‐GMA (70/30/10 wt%, PLA‐g‐GMA was a compatibilizer synthesized in our lab) was used as the research object. This work aims to analyze the mechanical properties response of biodegradable polymers products manufactured through FDM. Herein, the effect of 3D printing parameters including layer thickness, nozzle temperature, printing speed and platform temperature have been systematically…

In response to the nowadays battle against SARS-CoV-2, we designed a new class of high performant filter media suitable to advance the facemask technology and provide new efficient widespread solutions against virus propagation. By means of the electrospinning technology we developed filter media based on polyvinyl alcohol (PVA) nanofibers doped with AgNPs combining three main performance requirements: high air filtration efficiency to capture nanometer-size particles, low airflow resistance essential to ensure breathability and antimicrobial activity to inactivate aerosolized microorganisms. PVA/AgNPs electrospun nanofibers were produced by electrospinning the dispersion of colloidal silver into the PVA water solution. A widespread physicochemical characterization was addressed to the Ag colloidal suspension. The key functional performances of the electrospun nanofibers were proven by water stability, antibacterial activity, and filtration efficiency and pressure drop measurements performed under conditions representative of facemasks. We assessed a total bacterial depletion…

Abstract Blends of poly(butylene adipate‐co‐terephthalate)/polyglycolic acid (PBAT/PGA) were prepared by melt blending, in which PGA was used as reinforcing component. Impacts of PGA content on tensile property, microstructure, crystallization property, melt viscosity, barrier performance of the blends were researched. Compared with very soft behavior of PBAT, the tensile yield strength and modulus of PBAT/PGA (65/35) sample increased from 7.67, 62.6 MPa of neat PBAT to 12.05, 158.9 MPa, respectively. However, owing to poor PBAT/PGA interface compatibility, its elongation at break decreased significantly from 1082.1% to 88.7%. An epoxy chain extender (ADR) was used as reactive modifier to improve its interface compatibility and rheological property. The related physical properties of PBAT/PGA/ADR (65/35/x) samples with various ADR contents were evaluated in detail. It was found that ADR exerted relatively complex influences on the properties. Overall, compared with neat PBAT and PBAT/PGA (65/35) sample, the PBAT/PGA/ADR (65/35/x) samples exhibited better stiffness‐ductility balance…

Abstract Fluororubber (FKM) materials have excellent mechanical properties, and are widely used in automotive and aerospace fields. As fluorine rubber is a typical representative of new special rubber, the formula and mechanical test method of fluorine rubber have become one of the important issues at present. Multi‐factor optimization of fluororubber compound plays an important role in the mechanical properties of FKM. Based on the introduction of new materials in FKM compounding agents (reinforcing agent, softening plasticizer, anti‐aging agent, accelerator, vulcanizing agent, auxiliary agent and filler), this paper focuses on the research progress of characterization methods and mechanical properties of the composite materials combined with FKM.

Abstract Aromatic polyimides (PI) with low‐dielectric constant are becoming more and more important with the continuous development of high‐speed communication technology. Herein, high fluorine‐containing PI with low‐dielectric constant was prepared. First, a novel aromatic diamine monomer 4,4′‐(3,3′‐bis[trifluoromethyl]biphenyl‐4,4′‐diyl)bis(oxy)bis(3‐[trifluoromethyl]aniline) bearing multi‐trifluoromethyl groups (12FDA) was synthesized and characterized. Subsequently, a series of PI with high‐fluorine content (HFPI) were obtained by two‐step polymerization of 12FDA with three commercial dianhydrides. The polymer films cured at a maximum temperature of 310°C showed excellent thermal and mechanical properties with high‐glass transition temperatures (>250°C) and high‐storage modulus (> = 2.0 GPa). The 5% weight loss temperatures of HFPIs were all above 500°C, which indicated that HFPIs exhibited excellent thermostability. Meanwhile, HFPI exhibited low‐water absorption (<0.3%) and low‐dielectric constant (2.40–2.68 at 1 MHz). The excellent thermal, mechanical, and electrical…

Abstract This investigation intended at fabricating gelatin active packaging films based on nano‐sized droplets of coconut oil emulsified by Pickering emulsion (PE) using chitosan/Arabic gum (CH/AG) nanoparticles (NPs) as a stabilizer and in the presence of titanium dioxide NP (TiO2NPs) as an extra antimicrobial agent. The developed films were characterized by attenuated total reflectance–Fourier transmittanceinfrared, X‐ray diffraction, and scanning electron microscope. The antimicrobial, antioxidant, water vapor sorption isotherm, and mechanical properties of the prepared films were assessed. The (CH/AG) NPs weight ratios (1:1, 1:2, and 2:1) impact on particle size (PS), zeta potential, wettability, morphology, and in vitro cumulative release was investigated. The (CH/AG) NPs (1:2) exhibits the small PS (246.4 nm). (CH/AG) NPs and PE exhibit spherical and oval morphologies. The CH/AG (1:2) exhibits the higher water contact angle (85.7o). At the oil volume fraction (α) = 1.0, nearly 81% of the entrapped oil released from the NPs. Gelatin films enriched with P atα = 1.0 exhibits…

Abstract A multi‐component, fluorescent hydrogel of chitosan and gelatin using maleic acid as a cross‐linking agent was fabricated with improved mechanical and thermal properties. The FTIR spectroscopy and SEM studies confirmed the formation of a cross‐linked and porous hydrogel. The XPS studies confirmed the presence of rich functionalities over the surface of hydrogel. The hybrid hydrogel possessed strong blue emission band centered at 438 nm when excited with an absorption band centered at 384 nm. The fluorescent hydrogel was tested for selective detection of different heavy metal ions including Cr (VI) in the aqueous solution. The strong complexation among the functional groups of hydrogel and metal ions led to the quenching of hydrogel's fluorescence. The fluorescence of hydrogel was quenched significantly in the presence of Cr (VI) ions in comparison to the other heavy metal ions. The fluorescence‐quenching efficiency displayed a linear response to the Cr (VI) concentration in the range of 1–14 nM with a lower detection limit of 0.12 nM. Embraced with good sensitivity and…

Abstract Three types of ultra‐high molecular weight polyethylene (UHMWPE) with different entangled state and molecular weight were blended with high‐density polyethylene (HDPE) matrix by melt blending. Rheology, 2D‐SAXS, 2D‐WAXD, DSC, and mechanical tests were used to study the evolution and difference of microstructure and mechanical properties of the blends. The addition of weakly entangled UHMWPE enhanced the chain diffusion and chain orientation ability under a specific flow field. Thus, the rheological properties and mechanical properties of the blends were improved with the mix of weakly entangled UHMWPE. The mechanical properties enhancement effect of HDPE/UHMWPE blends with weakly entangled UHMWPE was owing to the shish‐kebab structure formed in the injection molding process. The molecular chains of UHMWPE with a low degree of entanglement and high molecular weight increased the lamella size and crystallinity of the blends during processing. This leads to the formation of more oriented shish structures and more kebab lamella. Besides, the molecular chains of weakly entangled…

Abstract Gelatin (Gel)‐based pH‐ and thermal‐responsive magnetic hydrogels (MH‐1 and MH‐2) were designed and developed as novel drug delivery systems (DDSs) for cancer chemo/hyperthermia therapy. For this goal, Gel was functionalized with methacrylic anhydride (GelMA), and then copolymerized with (2‐dimethylaminoethyl) methacrylate (DMAEMA) monomer in the presence of methacrylate‐end capped magnetic nanoparticles (MNPs) as well as triethylene glycol dimethacrylate (TEGDMA; as crosslinker). Afterward, a thiol‐end capped poly( N ‐isopropylacrylamide) (PNIPAAm‐SH) was synthesized through an atom transfer radical polymerization technique, and then attached onto the hydrogel through “thiol‐ene” click grafting. The preliminary performances of developed MHs for chemo/hyperthermia therapy of human breast cancer was investigated through the loading of doxorubicin hydrochloride (Dox) as an anticancer agent followed by cytotoxicity measurement of drug‐loaded DDSs using MTT assay by both chemo‐ and chemo/hyperthermia‐therapies. Owing to porous morphologies of the fabricated magnetic hydrogels…

Abstract Nowadays, polyimide (PI) with low dielectric constant is expected to be widely applied in microelectronics. For this reason, hollow glass microspheres (HGM) modified by silane coupling agent KH‐550 (K‐HGM), a series of HGM/PI and K‐HGM/PI composite films with excellent thermal performance, hydrophobic and low dielectric constant were fabricated by in situ polymerization. The effect of HGM/K‐HGM content on the properties of composite films was studied. The superior heat resistance of HGM can improve the thermal performance of composite films. Due to silane coupling agent KH‐550, K‐HGM exhibits a good interfacial compatibility with PI matrix and forms an interfacial adhesion region. With the HGM loading of 6%, comparing with pure PI films, the glass transition temperatures (Tg) of composite films were dramatically increased by 32.3°C. Especially, the low dielectric constant of 2.21 and dielectric loss of 0.0059 at 1 MHz were obtained for the PI/K‐HGM composite film with addition of 8 wt%. Thus, PI/K‐HGM composite films show more excellent performance. The current work…

Abstract The increasingly disturbing electromagnetic wave pollution has intensified research for high‐performance shielding materials to protect humans and the environment. It remains a great challenge to combine high electromagnetic interference (EMI) shielding performance with mechanical robustness and stretchability. These crucial features have been simultaneously achieved in this work by using a facile method to prepare elastomer/MXene nanocomposites. An EMI shielding effectiveness of 49 dB was obtained from a 1‐mm thick nanocomposite film at 19.6 vol% of MXene; the film has a density of 1.25 g/cm3. The outstanding electrical conductivity of MXene – 4350 ± 125 S·cm−1 – provided free charge carriers in the matrix to absorb electromagnetic signals, leading to the dominance of absorption mechanism over reflection mechanism. Owing to a nanofiller modification step, the nanocomposite films demonstrated not only outstanding EMI shielding but sufficient strength and stretchability. A nanocomposite at 14.0 vol% exhibited Young's modulus of 15.85 ± 0.75 MPa and tensile strength 25.94 ±…

Abstract To improve the mechanical properties of polyvinyl alcohol (PVA) fibers, a series of PVA fibers were prepared via dry‐wet spinning with cross‐linking of boric acid (BA) (PVA/BA fibers), and using the mixed solvent of dimethyl sulfoxide and water. Moreover, the final PVA/BA fibers were characterized by Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), differential scanning calorimetery (DSC), thermogravimetric analyzer (TGA), powder X‐ray diffraction (XRD) and yarn strength tester. Furthermore, with the increasing of BA content, FTIR analysis showed that the degree of crosslinking of BA with PVA increased. SEM images of final PVA/BA fibers presented smooth surfaces, and the diameters decreased firstly and then increased. DSC, TGA, and XRD analysis indicated that the melting temperatures, thermal properties and crystallinities first increased and then decreased with the increasing of BA content. In addition, mechanical properties measurements illustrated that the cross‐linking existed at an optimal BA content of 0.3 wt%, and PVA/BA‐0.3 fiber had…

Abstract Ultra‐high temperature dramatically deteriorates rheological properties and filtration performance of water‐based drilling fluids (WBDFs), especially for a salt‐gypsum formation that greatly restricts the application of WBDFs in ultra‐deep well drilling operations. Hence, the research in this article used an anionic copolymer (DANS) prepared by N , N ‐dimethylacrylamide, 2‐acrylamide‐2‐methylpropanesulfonic acid, N ‐vinylpyrrolidone, and sodium 4‐styrenesulfonate as an anti‐ultra‐high temperature and anti‐salt contamination filtrate reducer. Due to its multiple bulky cyclic structures in the side chain, DANS exhibits excellent thermal stability in the thermal gravimetric, rheological, and filtration tests. By adding 1.0 wt% DANS, the American Petroleum Institute (API) filtration volume of sodium bentonite‐based fluids (SBT‐BFs) decreased from 56.0 to 9.2 ml after aging at 240°C. Even under both 20 wt% NaCl contamination and 240°C aging, SBT‐BFs with 2.0 wt% DANS could maintain a filtration volume of 9.4 ml, whereas SBT‐BFs without DANS reached a filtration volume of 203.0…

Abstract Phenolic impregnated carbon ablator (PICA) as a typical lightweight ceramic ablative material is widely used in thermal protection systems (TPS). However, the rigidity and poor mechanical property of the existing PICA limit its application in flexible TPS. For the purpose of solving these problems, a novel lightweight, flexible, and heat‐insulated PICA material is first successfully fabricated using resorcinol‐formaldehyde (RF) aerogel as matrix and flexible carbon fiber felt as reinforcement through vacuum impregnating and ambient pressure drying. The prepared composites have relatively low densities (0.20 ~ 0.27 g/cm3) and low thermal conductivities (~0.11 W/[m·K]) at room temperature. The flexible PICA has adjustable flexibility through changing the RF concentration of impregnated sols and exhibits excellent folding endurance, which can be folded more than 500 times without fracture. The material can recover to its original shape without fracture when the compressive strain is up to 60%, which shows high compressive resilience properties. The result of the back‐face…