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Polyimides (PIs) can be synthesized from diisocyanate and dianhydride through a direct heating one-step polymerization process with a lower temperature and shorter reaction time than the traditional stepwise heating route. This study discusses the properties of resulting PIs produced using the direct one-step heating procedure with N-methyl-2-pyrrolidinone (NMP) as the solvent. Based on the structural and property evaluations, the reaction system used yields not only organo-soluble PIs but also ultra-high thermal stability up to 580 °C at 5% weight loss. The obtained PIs have medium molecular weights ranging from 26.6 to 35.6 kg/mol. This reaction system is found to be fast and efficient in producing high thermoresistant PI materials with improved processing ability. These findings provided insights on the energy-efficient one-step synthesis of PIs specifically derived from diisocyanate and dianhydride. [ABSTRACT FROM AUTHOR]

Low critical solution temperature (LCST) of commonly used thermoresponsive polymers in water is basically dominated by hydrophobic interactions. Herein, a novel thermoresponsive system based on electrostatic interactions is reported. By simply loading aluminum chloride (AlCl3) into non‐responsive poly(2‐hydroxyethyl acrylate) (PHEA) hydrogels, PHEA‐Al gels turn to have reversible thermoresponsive behavior between transparent and opaque without any volume change. Further investigations by changing metal ion‐polymer compositions unravel the necessity of specific electrostatic interactions, namely, cation‐dipole bonding interactions between hydroxy groups and trivalent metal ions. The thermoresponsive hydrogel demonstrates high transparency (≈95%), excellent luminous modulation capability (>98%), and cyclic reliability, suggesting great potential as an energy‐saving material. Although LCST control by salt addition is widely known, salt‐induced expression of thermoresponsiveness has barely been discussed before. This design provides a new approach of easy fabrication, low cost, and scalability to develop stimuli‐responsive materials. [ABSTRACT FROM AUTHOR]

Bio-based polyureas (PUs) with main-chain furan rings were synthesized by the polyaddition of 2,5-bis(aminomethyl)furan with various diisocyanates, such as methylene diphenyl diisocyanate. Several PU's were soluble in polar organic solvents, and were cast to form thermomechanically stable films with softening temperatures of over 100 °C. The furan rings of the PU main chains underwent a dynamic Diels-Alder (DA) reaction with bismaleimide (BMI) cross-linkers. While the mixed solution of PU and BMI did not show any apparent signs of reaction at room temperature, the DA reaction proceeded to form gels upon heating to 60 °C, which became a solution again by further heating to 80 °C (retro-DA reaction). The solution phase was maintained by rapid quenching from 80 °C to room temperature, while the gel was reformed upon slow cooling. The recovered gels exhibited self-healing properties. A scratch made by a hot knife at temperatures above 80 °C disappeared spontaneously. When two different gels were cut using a knife at room temperature, placed in contact with each other, and heated to 60 °C, they fused. The ability to control the DA/retro-DA reaction allowed gels of varying composition to heal. [ABSTRACT FROM AUTHOR]

Aliphatic polyesters, such as poly(lactic acid), which degrade by hydrolysis, from naturally occurring molecules form the main components of biodegradable plastics. However, these polyesters have become substitutes for only a small percentage of the currently used plastic materials because of their poor thermal and mechanical properties. Polymers that degrade into natural molecules and have a performance closer to that of engineering plastics would be highly desirable. Although the use of a high-strength filler such as a bacterial cellulose or modified lignin greatly increases the plastic properties, it is the matrix polymer that determines the intrinsic properties of the composite. The introduction of an aromatic component into the thermoplastic polymer backbone is an efficient method to intrinsically improve the material performance. Here, we report the preparation of environmentally degradable, liquid crystalline, wholly aromatic polyesters. The polyesters were derived from polymerizable plant-derived chemicals—in other words, ‘phytomonomers’ that are widely present as lignin biosynthetic precursors. The mechanical performance of these materials surpasses that of current biodegradable plastics, with a mechanical strength, σ, of 63 MPa, a Young’s modulus, E, of 16 GPa, and a maximum softening temperature of 169 ∘C. On light irradiation, their mechanical properties improved further and the rate of hydrolysis accelerated. [ABSTRACT FROM AUTHOR]

The present study focuses on nanoparticles composed of amphiphilic poly(γ-glutamic acid) (γ-PGA) as potential protein carriers. Amphiphilic graft co-polymers composed of γ-PGA as the hydrophilic backbone and L-phenylalanine ethylester (L-PAE) as the hydrophobic segment were synthesized by grafting L-PAE to γ-PGA using water-soluble carbodiimide (WSC). Due to their amphiphilic properties, the γ-PGA-graft-L-PAE co-polymer formed monodispersed nanoparticles in water. The particle size of the nanoparticles composed of γ-PGA-graft-L-PAE (γ-PGA nanoparticles) was about 200 nm and showed a highly negative zeta potential. To evaluate their potential applications as multifunctional protein carrier, we prepared protein-entrapped γ-PGA nanoparticles by encapsulation, covalent immobilization or physical adsorption methods. For this purpose, 11 different proteins with various molecular weights and isoelectric points (pI values) were used as model proteins. The encapsulation of the protein into the nanoparticles was observed for all tested proteins. The amount of protein covalently immobilized or adsorbed onto the nanoparticles showed different tends based on the molecular weight and pI of each protein. Positively charged proteins could be adsorbed onto the negatively charged nanoparticles by electrostatic interaction. Moreover, it was found that enzyme-encapsulated nanoparticles showed higher enzymatic activity than surface-immobilized nanoparticles. These results indicated that the enzymatic activity of the enzyme-entrapped nanoparticles was significantly affected by the conjugation method, and that encapsulation was the optimal method for the conjugation of proteins and nanoparticles. It is expected that the γ-PGA nanoparticle will have great potential as multifunctional carriers in pharmaceutical and biomedical applications, such as drug and vaccine delivery systems. [ABSTRACT FROM AUTHOR]

Abstract: Porous linear-polymer penetrating networks (semi-IPNs) were prepared by the radical polymerization of acrylic acid (AAc) inside porous poly(N-isopropylacrylamide) hydrogels with “nano-sized tract networks (nano-tracts).” The deswelling behavior was investigated by measuring the time course of the swelling ratio change of the semi-IPNs just after the temperature or pH was changed. Although the incorporation of PAAc linear chains into the PNIPAAm hydrogel networks should facilitate deswelling, nonporous semi-IPNs showed only a slow thermoresponse under low pH conditions, and a slow pH-response under a high temperature. On the other hand, the porous semi-IPNs showed a rapid deswelling in response to either a change in pH or temperature, regardless of the environment, presumably due to the nano-tracts through which the water was rapidly released from the hydrogel without any interference by network shrinking. The novel network design of these nano-tracted semi-IPNs may be useful for high performance, dual molecule-release functions. [Copyright &y& Elsevier]

Abstract: Uniform polymeric nanoparticles with various morphologies of projection coronas like the viruses in the coronavirus group have been formed by the self-organization of macromolecular chains polymerizing in a dispersion system of styrene (St), acrylonitrile (AN) and poly(ethylene glycol) monomethoxymonomethacrylate (PEGm) in a polar solvent (water/ethanol). An increase in the water composition reduced the crystallization degree of AN units, resulting in a variety of the nanoparticle morphology such as the increased particle size, the reduced projection size, the increased projection number, and the decreased inter-projection distance. The difference in the projection morphology strongly affected a dispersibility in water. [Copyright &y& Elsevier]

Abstract: The objective of the present study was to prepare nanoparticles composed of poly(γ-glutamic acid) (γ-PGA) and l-phenylalanine ethylester (l-PAE) in order to evaluate the possibility of using these nanoparticles as protein carriers. Novel amphiphilic graft copolymers composed of γ-PGA as the hydrophilic backbone and l-PAE as the hydrophobic segment were successfully synthesized by grafting l-PAE to γ-PGA using water-soluble carbodiimide (WSC). Due to their amphiphilic properties, the γ-PGA–graft-l-PAE copolymers were able to form nanoparticles. The size of the γ-PGA nanoparticles was measured by photon correlation spectroscopy (PCS) and showed a monodispersed size distribution with a mean diameter ranging from 150 to 200 nm. The solvents selected to prepare the γ-PGA nanoparticles by a precipitation and dialysis method affected the particle size distribution. To evaluate the feasibility of vehicles for these proteins, we prepared protein-loaded γ-PGA nanoparticles by surface immobilization and encapsulation methods. Ovalbumin (OVA) was used as a model protein and was immobilized onto the γ-PGA nanoparticles or encapsulated into the inner core of these nanoparticles. Moreover, these OVA-encapsulated γ-PGA nanoparticles could be preserved by freeze-drying process. The results of cytotoxicity tests showed that the γ-PGA and γ-PGA nanoparticles did not cause any relevant cell damage. It is expected that biodegradable γ-PGA nanoparticles can immobilize proteins, peptides, plasmid DNA and drugs onto their surfaces and/or into the nanoparticles. These nanoparticles are potentially useful in pharmaceutical and biomedical applications. [Copyright &y& Elsevier]

IgG responses to antigen-nanosphere hybrids were studied in mice. Cholera toxin (CT) was covalently immobilized onto the surface of polymeric nanospheres (NS) with a nanophase-separated structure consisting of a polystyrene core and a poly(methacrylic acid) graft corona. Reaction conditions favoring the dehydroxide condensation reaction of the amino group of the CT with the carboxyl group of NS effectively immobilized CT onto their surface. When CT-immobilized nanospheres (CT-NS) were suspended in aqueous solution and administrated to mice either intranasally or intramuscularly, serum IgG titers elevated with increasing time and reached a maximum level at 8 weeks after immunization. On the other hand, intranasal administration of CT alone induced an even higher serum IgG titer than that of CT-NS at 4 weeks. However, the titer gradually decreased thereafter. Thus, polymeric NS may be an effective substrate to covalently immobilize antigen on their surface, steadily inducing a high level of IgG production in response to the intranasal administration. [ABSTRACT FROM AUTHOR]

Shellac, a naturally degradable material, was used as a carrier to load some functional and active compounds in the packaging fields. It is rarely used directly as a substrate to prepare packing films due to its unsatisfactory solubility and mechanical properties. In this research, ammonia was used as a solvent to dissolve shellac which helped form a smooth and tough shellac film via the interaction between shellac and ammonia. Moreover, a shellac composite film was formed by additional cellulose nanofibers (CNF). The properties of the shellac composite films (SAmCxPS) were regulated by modulating the concentrations of ammonia and CNF. The prepared films were characterized by a scanning electron microscope (SEM), NanoS Zetasizer, thermogravimetric analysis (TGA), and UV-Vis spectrophotometer, and their tensile strength was also determined. The results revealed that the shellac composite films were successfully prepared and were very thermally stable. The maximum tensile stress of the shellac composite films with 0.9 wt% CNF could reach 20.5 MPa. Such a high tensile stress indicated significantly improved mechanical properties. Moreover, the shellac composite films also showed good UV barrier properties, which reduced the ripeness of the fruit. Overall, the improvement in the stability and mechanical and UV barrier properties of shellac can broaden its application in the field of packaging. [ABSTRACT FROM AUTHOR]

The molecular orientation of liquid crystalline (LC) hydrogels has the potential to induce a range of functionalities that can deliver great mechanical strength. Sacran is a supergiant LC polysaccharide isolated from the cyanobacterium Aphanothece sacrum with a high amount of anionic functional groups such as sulfates and carboxylates. In this article, ultra-strong sacran hydrogels and their dried fibers were produced by cross-linking under injection flow with trivalent metal ions such as Al3+, Cr3+, Fe3+, In3+, and rare-earth metal ions such Er3+ and Sr3+. Crossed-polarizing microscopy and X-ray diffraction imaging revealed a uniaxial molecular orientation in the LC gel fiber, resulting in outstanding mechanical characteristics. [ABSTRACT FROM AUTHOR]

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

The effects of water absorption on the electric resistivity and dielectric constant of polyimide (PI) and poly(ethylene terephthalate) (PET) were investigated, and the mechanism of deterioration in electrical insulation properties was discussed. The polyimides are poly(oxydianiline pyromellitimide) (PMDA–ODA) and poly(para-phenylene diamine biphenyltetracarboxydiimide) (BPDA–PDA). These polymer films were immersed in pure water for various immersion times at room temperature, and the water absorption ratio was evaluated. The electric resistance for these films was measured at room temperature using a high-resistance meter, and the dielectric constant at room temperature was measured using an LCR meter in a frequency range of 200 kHz to 2 MHz. The absorption ratios at equilibrium absorption for PMDA–ODA, BPDA–PDA, and PET were 2.7, 2.5, and 0.5%, respectively. The critical volume fraction of the percolation threshold of electric conductivity due to water absorption was 0.034 for both PMDA–ODA and BPDA–PDA. On the other hand, PET did not show a significant decrease in the resistivity. For both PIs and PET, the dielectric constant observed could be explained by a series model of the respective capacitances of pure water and polymer. Actually, the resistivity of samples cut from the edges of the film after water absorption was almost the same value as that in the dry state. These results suggest that the absorbed water molecules are not uniformly dispersed in the film but are localized at the edges of the film even after the absorption equilibrium has been reached. [ABSTRACT FROM AUTHOR]

The mechanical properties for paper sheets composited with glucose (Glc), methyl cellulose (MC), and carboxymethyl cellulose (CMC) were investigated. The paper composites were prepared by immersing paper sheets in aqueous solutions of these materials and drying at 100 °C for 30 min. The stress–strain curves for these paper composites were measured by a uniaxial tensile apparatus with a stretching speed of 2 mm/min. The breaking stress and strain for untreated paper were 24 MPa and 0.016, respectively. The paper composites demonstrated stress–strain curves similar to the untreated paper; however, the breaking point largely differed for these composites. The breaking strain and breaking stress for the Glc composite slightly decreased and those for the MC composite gradually increased with the concentration of materials composited. Significant increases in the mechanical properties were observed for the CMC composite. The breaking stress, breaking strain, and breaking energy for the 3 wt.% CMC composite were 2.0-, 3.9-, and 8.0-fold higher than those for untreated paper, respectively. SEM photographs indicated that the CMC penetrated into the inner part of the paper. These results strongly suggest that the mechanical improvement for CMC composites can be understood as an enhancement of the bond strength between the paper fibrils by CMC, which acts as a bonding agent. It was also revealed that the breaking strain, breaking stress, and breaking energy for the CMC composites were at maximum at the first cycle and decreased gradually as the immersion cycles increased. [ABSTRACT FROM AUTHOR]

This paper presents the results of unidirectional strain-controlled experiments on fibrous electrospun networks used to study damage formation during elongation. The experimental loading curve shows a symmetrical parabolic type dependence at large scale and saw tooth-like force−extension behaviour at small scale. The damage formation was quantified by determining the number and the magnitude of abrupt force drops. The experiments evidenced that damage evolution is a consequence of strain induced random events. The frequency distribution of the number of damages as well as the magnitude of rupture force were represented by histograms. The results of the present study provide a better insight into damage tolerance and complex nonlinear tensile properties of electrospun networks. In addition, it could suggest a possible probabilistic approach to the fiber bundle model which has mainly motivated this study. [ABSTRACT FROM AUTHOR]

An all-environmentally stable eutectogel by combination of hydrophobic deep eutectic solvent and polymer network is fabricated. The flexible eutectogel with extraordinary transparency could be adhered on human skin and detect the human physiology signal even in the aqueous environment. [Display omitted] • Eutectogel with superior underwater stability is fabricated by all hydrophobic structure. • The abundant ion-dipole interactions and phase separation within the eutectogel endow it with excellent toughness. • Eutectogel maintain stable adhesiveness for a long time under various harsh environments. • The water-resistant eutectogel is of great potential in underwater ECG monitoring and motion detecting. Although the deep eutectic solvent based gels (eutectogels) are considered to be the next-generation stretchable electronics, it is still greatly challenging to develop an all-environmentally stable eutectogel because of the high water sensitivity of the DES. Herein, a eutectogel with high transparency, tailorable stretchability, and water-resistant properties is reported. First, a novel colorless hydrophobic deep eutectic solvent (DES) with good conductivity (1.2 mS cm−1), and low viscosity is found by forming hydrogen bonding between amphiphilic hydrogen donor and non-hygroscopic hydrogen acceptor. Moreover, abundant ion–dipole interactions between the polymer networks and DES are designed into the eutectogels and verified by 2D infrared spectrum, resulting in ultra-durability of eutectogels in different circumstances (including pH 1–14, 30–90 RH% and 10–50 °C) for over 5 days. Furthermore, thanks to the ion–dipole interactions and phase separation induced by poor solvated hard polymer segments in DES, the eutectogel is endowed with tailorable mechanical property (0.1–0.8 MPa), long-term underwater adhesion capability (0.5 MPa on irons), high transparency (>93%) and excellent biocompatibility (>95%), which has never been seen in previously reported eutectogels. This hydrophobic eutectogel could be used as action recognition devices and vital sign monitor underwater, meeting the next generation of wearable devices. [ABSTRACT FROM AUTHOR]

New soluble biopolyimides were prepared from a diamine derived from an exotic amino acid (4-aminocinnamic acid) with several kinds of tetracarboxylic dianhydride. The biopolyimide molecular structural flexibility was tailored by modifying the tetracarboxylic dianhydride moiety. The obtained polyimides were soluble in various solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and even tetrahydrofuran. It was observed that the biopolyimide solubility was greatly dependent upon the structural flexibility (torsion energy). Flexible structure facilitated greater solubility. The synthesized biopolyimides were largely amorphous and had number-average molecular weight (Mn) in the range (5–8) × 105. The glass transition temperatures (Tg) of the polymers ranged from 259–294 °C. These polymers exhibited good thermal stability without significant weight loss up to 410 °C. The temperatures at 10% weight loss (Td10) for synthesized biopolyimide ranged from 375–397 °C. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Current biomass-derived plastics are mostly aliphatic. • Aromatic plastics can be synthesized using 4-aminocinnamic acid, an amino acid. • Large-scale 4-aminocinnamic acid (4ACA) preparation was established. • Bulk 4ACA preparation will accelerate development of super engineering bioplastics. Abstract Aromatic amines are base materials for generating super-engineering plastics such as polyamides and polyimides. Recombinant Escherichia coli ferments 4-aminocinnamic acid (4ACA) from glucose, and it can be derived to plastics of biomass origin with extreme thermal properties. Here, we scaled-up 4ACA production by optimizing microbial fermentation processes. The initial fermentation of 4-aminophenylalanine (4APhe) using E. coli generated the papABC genes of Pseudomonas fluorescens that produced 4APhe with a volumetric mass transfer coefficient (k L a) of 70 h−1 in 115 L of culture broth, and 334 g of 4APhe at a final concentration of 2.9 g 4APhe L−1. Crude 4APhe prepared from the fermentation broth was bioconverted to 4ACA by an E. coli strain producing phenylalanine ammonia lyase of the yeast Rhodotorula glutinis. The E. coli cells cultured under optimized conditions converted 4APhe to 4ACA at a rate of 0.65 g L−1 4ACA OD 600 −1. These processes resulted in the final derivation of 4.1 g L−1 of 4ACA from glucose. The 4ACA was purified from the reaction as a hydrochloric acid salt and photodimerized to 4,4'-diaminotruxillic acid, which was polycondensed to produce bioaromatic polyimides. Large-scale 4ACA production will facilitate investigations of the physicochemical properties of biomass-derived aromatic polymers of 4ACA origin. [ABSTRACT FROM AUTHOR]

Abstract: Cyanobacteria are regarded as very eco‐friendly microreactors for the production of various biomolecules such as polysaccharides by fixing not only carbon but also nitrogen in water. Cyanobacterial polysaccharides having various functional groups such as hydroxyls, carboxyls, sulfates, etc. have the ability to interact with metals or inorganics, to create bionanocomposites. Sacran, a supergiant cyanobacterial anionic polysaccharide extracted from the extracellular matrix of Aphanothece sacrum which is mass‐cultivated in freshwater, is mainly used to create functional bionanocomposites. Gel‐type bionanocomposites of sacran with various metal cations are formed and showed photoresponsive functions. Metal recovery is performed from the sacran bionanocomposite gels. Sacran chains are complexed with multi‐wall carbon nanotubes (MWCNT) to give viscose dispersion from which MWCNT bionanocomposites can be collected by electrophoresis. The MWCNT/sacran dispersion retains the capability of adsorbing various metal ions to form hardened hydrogel beads. Finally, natural inorganic sepiolite can be used for sacran bionanocomposites which show an efficient neodymium ion adsorption ability. Thus, cyanobacterial polysaccharides are useful for preparing eco‐friendly and functional bionanocomposites with various hard materials. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF) is widely used in the preparation of carbon-fiber-reinforced polymer composites (CFRP) in which it is combined with epoxy resin due to its good mechanical properties. Thermosetting bisphenol A epoxy resin, as one of the most common polymer materials, is a non-renewable resource, leading to a heavy environmental burden and resource waste. To solve the above problems and achieve high mechanical and thermal properties comparable to those of bisphenol A, herein, a high-performance, degradable and recyclable bio-based epoxy resin was developed by reacting the lignin derivative vanillin with 4-amino cyclohexanol via Schiff base. This bio-based epoxy resin showed a Young's modulus of 2.68 GPa and tensile strength of 44 MPa, 36.8% and 15.8% higher than those of bisphenol A epoxy, respectively. Based on the reversible exchange reaction of the imine bond, the resin exhibited good degradation in an acidic environment and was recoverable by heat treatment. Moreover, the prepared epoxy resin could be used to prepare carbon fiber (CF)-reinforced composites. By washing off the epoxy resin, the carbon fiber could be completely recycled. The recovered carbon fiber was well preserved and could be used again for the preparation of composite materials to realize the complete recovery and utilization of carbon fiber. This study opens a way for the preparation of high-performance epoxy resin and the effective recycling of carbon fiber. [ABSTRACT FROM AUTHOR]

The evaporative interface on polysaccharides has evolved to form hierarchical structures with moisture sensitivity to enable organisms to live in drying environments. Here, the discovery of the morphological instability of polysaccharides, especially the reversible self‐assembly/disassembly between micron‐fibers and microparticles in response to changes in aquatic environments, is reported. This is similar but different to the dynamic instability observed in cytoskeletal proteins, in terms of an accompanying the polymeric deformation. The formation of the polymeric fibers containing crystalline structures can be flexibly controlled by controlling the polymer concentration and salt concentration in aqueous mixtures. Moreover, the microparticles having crosslinking points in the interior acquire the ability to retain a larger number of water molecules in drying environments and behave as super‐moisturizing materials. [ABSTRACT FROM AUTHOR]

Highly-thermostable but degradable polyamides have been synthesized by a polycondensation of bio-derived itaconic acid salts with aromatic diamines to form heterocyclic pyrrolidone ring in the polymer backbone. The molecular weight was greater than 33,600 g/mol. Glass transition temperatures, T g , and 10% weight loss temperatures, T 10 , ranged 156–242 °C and 370–400 °C, respectively, which were higher than those of conventional bio-based plastics. However their processability was too low to process the fiber as specimens of mechanical tests. We then incorporated an appropriate amount of aliphatic moiety into the aromatic backbones to prepare the high-performance and processable polyamides with T g over 115 °C and T 10 over 355 °C. The processed fibers showed tensile strength and Young's modulus ranged 20–58 MPa and 0.2–2.3 GPa, respectively. The degradation behaviors inside soil and under ultraviolet-irradiation in water were additionally found. [ABSTRACT FROM AUTHOR]

Utilizing antibacterial packaging material is an effective approach to delay fruit rotting and spoilage thereby minimizing financial losses and reducing health harm. However, the barrier and mechanical properties of biodegradable antibacterial packaging materials are barely compatible with transparency. Herein, antimicrobial nanoparticles encapsulating citral (ANPs) were first prepared by emulsification under the stabilization of oxidized dextran (ODE) and ethylene diamine. Then, composite films with high transparency, good water vapor barrier, and mechanical and antibacterial properties for fruits packaging were prepared from chitosan (CS), carboxymethyl-glucan (CMG), poly(vinyl alcohol) (PVA), and ANPs by solvent casting strategy. The synergistic effects of electrostatic interaction and hydrogen bonding could regulate crystalline architecture, generating high transparency of the composite films (90 %). The mechanical properties of the composite film are improved with elongation at break up to 167 % and stress up to 32 MPa. The water vapor barrier property of the film is appropriate to the packed fruit for less weight loss and firmness remaining. Simultaneously, the addition of ANPs endowed the film with excellent antimicrobial and UV-barrier capabilities to reduce fruit mildew, thereby extending the shelf life of fruits. More importantly, the composite polymer solution could be sprayed or dipped directly on fruits as a coating for food storage to improve food shelf life, substantially expanding its ease of use and scope of use. [Display omitted] • The electrostatic and hydrogen interactions have positive effects on transparency and comprehensive properties. • CS-CMG-PVA-P composite film has a high transparency of 90%. • CS-CMG-PVA-P composite film has an appropriate WVP barrier. • CS-CMG-PVA-P composite film has an extra UV barrier. • CS-CMG-PVA-P composite film has good antibacterial properties. [ABSTRACT FROM AUTHOR]

Aromatic and functional polymers with processibility derived from biobased starting materials are prerequisite considering sustainable society. Poly(2,5‐benzimidazole)s are rigid‐rod polymers to show ultrahigh thermal stability such as flame retardance, while usually suffer from poor solubility. Here, poly(benzimidazole‐co‐amide)s are synthesized from two biobased monomers, 3,4‐diaminobenzoic acid and a semirigid comonomer, 4‐aminohydrocinnamic acid. The copolymers with an amide composition of 80 mol% and higher are soluble in widely used polar solvents to fabricate the films keeping high flame retardance, which is comparable with popular high‐performance polymers such as aromatic polyimides, polyetheretherketone, polyphenylene sulfide, etc. [ABSTRACT FROM AUTHOR]

Wetting phenomena play important roles in several technological applications and in many physical and biological thin-film phenomena, such as wetting, adhesion and friction. One of key issues of these studies is to control the surface energy (or wettability) dynamically for liquid transportation. We have developed a liquid crystal (LC) surface for use as a transport substrate since we expected that the surface energy of an LC surface can be controlled rapidly using an electric field. The rapid control of the polarisability (or wettability) of a liquid crystalline surface by an electric field has been demonstrated, together with the transportation of a liquid microdroplet. [ABSTRACT FROM AUTHOR]

Abstract: A novel thermotropic liquid-crystalline biocopolymer, poly{trans-4-hydroxycinnamic acid (4HCA: trans-coumaric acid)-co-lithocholic acid (LCA)}, was synthesized by a thermal polycondensation of 4HCA and LCA. When the LCA composition of P(4HCA-co-LCA) was 0, 5, 7, 23, 27, and 45mol%, the copolymers showed a nematic liquid-crystalline phase. The melting point of the copolymers was 120–250°C depending on the LCA composition, and showed a maximum at 7mol%. Wide angle X-ray diffraction (WAXD) analyses showed a typical diffraction pattern of a hexagonal arrangement for 0, 7, 23, and 27mol% LCA composition, which were cooled from a nematic melt. The other polymers showed no distinct diffraction. In particular, the copolymer of 7mol% LCA composition showed four distinct diffractions corresponding to spacings with a reciprocal ratio of 1, √3, 2, and √7, indicating the highest structural ordering of all copolymers prepared here. The results of the cell adhesion and static contact angle tests suggest that the 7mol% LCA composition copolymer had the highest hydrophobicity and cell adhesion ability, which was easily controlled by altering in feed. We conclude that the structural ordering may have a significant correlation with cell adhesion activity. [Copyright &y& Elsevier]

NAITO, S.,et al.: Biatrial Epicardial Pacing Prevents Atrial Fibrillation and Confers Hemodynamic Benefits After Coronary Artery Bypass Surgery. Biatrial pacing (BIP) can be more effective than standard right atrial pacing (RAP) in preventing atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG). However, the mechanisms and hemodynamic benefits of BIP have not been studied in detail. This study examined the efficacy and hemodynamic benefits conferred by overdrive epicardial BIP in preventing post-CABG AF. After undergoing CABG, 72 patients (mean age= 66± 12 years, 48 men) were randomly assigned to triggered BIP (BIP-AAT; n= 50) versus single RAP (RAP-AAI; n= 22). The hemodynamic effects of BIP were measured by right heart catheterization and echocardiography. The patients were monitored for 8.8± 2.4 days after CABG to detect episodes of AF. The incidence of AF was significantly lower in the BIP-AAT group (22.0%) than in the RAP-AAI group (59.1%, P<0.01). Cardiac output was significantly higher and pulmonary artery wedge pressure (PAWP) significantly lower during BIP-AAT than during RAP-AAI. The E-wave (65.2± 37.8 vs 57.8± 37.8 cm/s, P<0.05) was significantly higher during BIP-AAT, and the interval between atrial pacing spike and the end of A-wave (241± 18.4 vs 286± 17.2 ms, P<0.001) was significantly shorter during BIP-AAT than during RAP-AAI. Triggered BIP was well tolerated and significantly reduced the incidence of post-CABG AF compared to single-site RAP. The hemodynamic improvements conferred by BIP-AAT were due to a shortening of the inter-atrial conduction delay and greater contribution of left atrial contraction. These hemodynamic benefits may play a role in lowering intra-atrial pressure and in preventing AF.(PACE 2005; 28:S146–S149) [ABSTRACT FROM AUTHOR]

Optically transparent and heat‐resistant polymer films are useful in the field of organic glasses usable for electric insulators for panels, windows, optical devices, etc. A series of biopolyimides having non‐π‐conjugated backbones prepared using a renewable diamine, 4,4′‐diaminotruxillic acid dimethyl esters, and various dianhydride monomers were prepared and cast onto substrates to form transparent films with high heat resistances and good electric resistance. The second order orientation coefficients (P200) of the biopolyimide films were evaluated by polarized attenuated total reflection Fourier‐transform infrared spectroscopy, and the P200 values for the C−N stretching vibrations at a wavenumber of 1365 cm−1 displayed a good correlation with that for the aromatic C−C stretching at 1510 cm−1, regardless of the dianhydride structure. The in‐plane/out‐of‐plane birefringence and coefficients of linear thermal expansion exhibited strong correlations with P200 except for those of a few samples. Most of the biopolyimide films exhibited good transparencies with low birefringence and high electric resistance, which are applicable to flexible substrates with a low coefficient of thermal expansion for panel displays. [ABSTRACT FROM AUTHOR]

[Display omitted] Generation of long-range ordering of colloidal particles through anisotropic interactions is of growing interest in material designing. At submicron-scale, routine works use synthetic spheres or rods but the knowledge pertaining to assembly of binary combination of particles is severely restricted. Improved understanding of the fundamental aspects that drive self-assembly, can lead to robust strategies for fabrication of topographically oriented films. The fluidical geometry of a liquid crystalline (LC) solution of polysaccharide consisting of micron-sized rod and platelet units was explored. The solutions, characterized for their rheological behavior, were evaporated from a rectangular cavity. The assembly and orientation of the units was monitored by polarizing microscopy and the interparticle capillary forces approximated mathematically. The units deposited into an uninterrupted membrane upon interfacial evaporation, forming a bridge along the 8 mm gap, linking the substrates. The membrane, composed of a lamellar structure, was uniaxially oriented along the direction of the gap. The rheological estimations corroborated an extremely high value of viscosity with the presence of crosslinking junctions in this solution when compared to a solution with only rod units, capable of bridging a maximum of 1 mm. It has been demonstrated for the very first time that the presence of platelet-units contributes lateral capillary interactions and assist rod-units towards a wider, self-assembled structure. [ABSTRACT FROM AUTHOR]

An enhancement of environmental concern lately has improved the awareness of researchers in employing eco-friendly solvents for processing biopolymers. Recently, ionic liquids have been utilized to prepare biopolymer blends as they are non-volatile and recyclable. Biopolymers such as cellulose, chitin, chitosan, keratin, lignin, silk, starch, and zein are widely used for the preparation of biopolymer blends via dissolution in ionic liquids, followed by coagulation procedure. In this concise review, three types of ionic liquids based on imidazolium cations combined with different counter anions that are frequently utilized to prepare biopolymer blends are described. Moreover, three types of biopolymer blends that are prepared in ionic liquids were classified, specifically polysaccharide/polysaccharide blends, polysaccharide/polypeptide blends, and polysaccharide/bioplastic blends. The physicochemical properties of biopolymer blends prepared in different imidazolium-based ionic liquids are also concisely reviewed. This paper may assist the researchers in the polymer blend area and generate fresh ideas for future research. [ABSTRACT FROM AUTHOR]

In contrast to convective self-assembly methods for colloidal crystals etc., "convective meniscus splitting method" was developed to fabricate three-dimensionally ordered polymeric structures. By controlling the geometry of evaporative interface of polymer solution, a deposited membrane with uniaxial orientation and layered structures can be prepared. Here it is demonstrated that xanthan gum polysaccharide microparticles with diameter ~ 1 µm can bridge a millimeter-scale gap to form such a membrane because the capillary force among the particles is more dominant than the gravitational force on the evaporative interface. This method is applicable for various substrates with a wide range of wettability (water contact angle, 11°–111°), such as glass, metals, and plastics. The specific deposition can be also confirmed between frosted glasses, functional-molecules-modified glasses, and gold-sputtered substrates. By using such a universal method, the membrane formed on a polydimethylsiloxane surface using this method will provide a new strategy to design a functional polysaccharide wall in microfluidic devices, such as mass-separators. [ABSTRACT FROM AUTHOR]

4-Aminophenylalanine (4APhe), an exotic amino acid which is obtained as a microorganism metabolite of glucose, is polycondensed with various tetracarboxylic dianhydrides as a diamine monomer to obtain poly(amic acid)s. Subsequent thermal imidization of poly(amic acid)s is made at 220 °C with stepwise heating from 100 °C. Some of the obtained polyimides (PIs) exhibited good solubility in organic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and more. The progress of imidization was observed by proton nuclear magnetic resonance and infrared spectroscopy to confirm that the imidization ratio was up to 98%. Carboxylate group of the side-chains of PIs affected their solubilities despite the high imidization ratio, and the solubility was lost for any organic solvents by decarboxylation at 280 °C, confirmed from mass-loss of thermogravimetric analysis. Thus, a new series of PIs were obtained with abilities of solvent-molding in PI state and thermal resistivity enhancement by further heating after molding. [ABSTRACT FROM AUTHOR]

Epidermal growth factor (EGF) accelerates epidermal regeneration, and it is widely studied as a wound-healing agent. However, the special carrier for the topical administration of EGF is urgently needed to deliver EGF on the wound site. In a preceding study, sacran hydrogel film (Sac-HF) showed a possible use as a dressing material for wound healing, as well as a good capability as a drug carrier. In the current study, we prepared Sac-HF containing EGF (Sac/EGF-HF) and then characterized their physicochemical properties, including thickness, swelling ratio, degradability, tensile strength, and morphology. In addition, we have also conducted thermal and crystallography studies using differential scanning calorimetry (DSC) and X-ray diffraction, respectively. Furthermore, we investigated the in vitro influence of Sac/EGF-HF on cell migration using a fibroblast cell line. Morphology study confirmed that the casting method used for the film preparation resulted in a homogeneous film of Sac/EGF-HF. Furthermore, EGF significantly increased the thickness, tensile strength, and degradability of Sac/EGF-HF compared to Sac-HF. Sac/EGF-HF had a lower swelling ability compared to Sac-HF; this result corroborated the tensile strength result. Interestingly, X-ray diffraction and DSC results showed that Sac/EGF-HF had an amorphous shape. The in vitro studies revealed that Sac/EGF-HF induced the fibroblast migration activity. These results conclude that Sac/EGF-HF has the potential properties of HF for biomedical applications. [ABSTRACT FROM AUTHOR]

Bio-based polyamides with high transparency and low yellowness were synthesized using 4,4′-bis(trifluoroacetamido)-α-truxillic acid (ATA-F1) and 4,4′-bis(pentafluoropropionamido)-α-truxillic acid (ATA-F2) as a fluoroalkylated aromatic dicarboxylic acid, and various aromatic diamines. The introduction of fluorine side chains improved the transparency of the polyamide film, and suppressed its yellowness. On the other hand, water repellency, which should be a general characteristic of the fluorinated polymers, was not observed. By using ATA-F1 and various aromatic diamines, aromatic and fluorinated polyamides were obtained. In addition, these also demonstrated a high transparency and a low yellowness index. The heat resistance properties of all the obtained polyamides was over 250 °C, and the characteristics of the bio-based polyamides from 4-aminocinnamic acid derivatives were retained. [ABSTRACT FROM AUTHOR]

Uniaxial orientation is highly desirable for fabricating advanced soft materials. Liquid crystal (LC) polymer deposition was strategically manipulated at the air-LC interface, by controlling the drying temperature and initial concentration of aqueous solution of xanthan gum in a limited space. Interface-assisted orientation led to membrane-like depositions bridging the millimeter-scale gap between the substrates both, vertically and horizontally. The applicability of this approach lies in synchronization of the molecular orientation beyond their individual LC domains into the condensed state. Cross-polarized microscopy and SEM analysis correlated the orientation of the deposited polymer with the controlled mobility of xanthan gum LC domains at the evaporative interface. Subsequently, a phase diagram was prepared for the variety of oriented structures, depending upon the drying conditions. The deposited membrane behaved as an oriented hydrogel showing reversible anisotropic swelling/deswelling only along its thickness. [ABSTRACT FROM AUTHOR]

Abstract High-performance bio-based plastics can make a major contribution to environmental sustainability. A series of high-performance poly(2,5-benzoxazole- co -2,5-benzimidazole)s (PBO- co -PBI) bio-based plastic films, were developed using the aromatic biomolecule 3-amino-4-hydroxybenzoic acid and the commercial product 3,4-diaminobenzoic acid. The partially bio-based PBO- co -PBI films exhibit higher thermal and mechanical performance than conventional bio-based polymers such as polyamide 11 or poly(lactic acid). The robust PBO- co -PBI films exhibit lower dielectric constants (ε r) than conventional high-performance aromatic polymers, attaining the value comparable to those of polyethylene or polypropylene. Highlights • (PBO- co -PBI)s were derived using bio-monomer 3-amino-4-hydroxybenzoic acid and commercial 3, 4-diaminobenzoic acid. • Aromatic bio-base plastics having high thermo-mechanical stability was developed. • Bio-bases plastic films having low dielectric constants and high volume resistivity were developed. [ABSTRACT FROM AUTHOR]

Abstract Simple and bulk preparation of catecholic polymers is challenging. Herein, we describe a novel bio-copolyester poly(DHHCA- co -4HPPA) (polyHH4P) prepared via thermal polycondensation of renewable resources 3,4-dihydroxyhydrocinnamic acid (DHHCA) and 3-(4-hydroxyphenyl) propanoic acid (4HPPA) in one pot. PolyHH4P exhibited strong adhesion properties on diverse materials, and its adhesive strength was highly dependent on the DHHCA composition (C DHHCA). PolyHH4P with 25% C DHHCA showed the highest shear strength at fracture, with values of 10.3 MPa on carbon, 9.6 MPa on glass, and 6.2 MPa on steel substrates, and these values are higher than the corresponding values for commercial instant super glue. Furthermore, the structural effects of para -hydroxyphenylpropionic acid (para -HPPA) and meta -hydroxyphenylpropionic acid (meta -HPPA) moieties on the properties of the prepared polymers were studied. PolyHH4P with the para -HPPA moiety showed an evidently improved glass transition temperature (T g s) relative to that of polyHH3P with meta- HPPA at the same C DHHCA , such as 19 °C increase at 25 mol% C DHHCA. However, unexpectedly, polyHH4P showed weaker adhesive shear strength than polyHH3P at the same C DHHCA mol%. We discussed the effects of C DHHCA , degree of crystallinity (CD), degree of branching (BD), catechol groups, and polymer chain rigidity on their properties. The difference in the adhesive strength of polyHH4P and polyHH3P can probably be ascribed to the higher symmetry and poorer flexibility in polyHH4P. The polyHH4P with an introduced rigid moiety and characterized by strong adhesion and an appropriately improved T g s is expected to have potential applications in various medical fields, for example, as a dental adhesive. Graphical abstract Image 1 Highlights • Mussel-inspired novel bio-copolyesters were prepared by a thermal polycondensation of renewable resources monomers. • Bio-copolyesters exhibited strong adhesion properties on a wide range of materials. • Adhesive strength of these copolymers was greatly related with C DHHCA. • Effects of meta - or para -hydroxyphenylpropionic acid segments on their properties were studied. • Copolymers with meta -HPPA show improved T g s but lower adhesive strength than those with para -HPPA segments. [ABSTRACT FROM AUTHOR]

In this study, novel α-truxillic and β-truxinic acid-based, bio-derived diesters have been developed as internal donors for preparing Ziegler-Natta (ZN) catalysts. Impacts of these bio-derived diesters were investigated on the chemical composition, the morphology, the mode of adsorption, and the propylene polymerization performance of the catalysts in comparison to the most widely used fourth-generation catalyst containing dibutyl phthalate. The molecular structures of the diesters and the particle morphology of the catalysts were preserved in the catalyst preparation. The bio-derived diesters afforded ZN catalysts with a reasonable activity and stereospecificity in propylene polymerization along with similarly broad molecular weight distribution (MWD) as the phthalate-based catalyst. Another promising feature of the catalysts was an opposite hydrogen response in terms of expansion of MWD upon the addition of H 2 . [ABSTRACT FROM AUTHOR]

Biomass plastics are expected to contribute to the establishment of a carbon-neutral society by replacing conventional plastics derived from petroleum. The biomass-derived aromatic amine 4-aminocinnamic acid (4ACA) produced by recombinant bacteria is applied to the synthesis of high-performance biopolymers such as polyamides and polyimides. Here, we developed a microbial catalyst that hydrogenates the α,β-unsaturated carboxylic acid of 4ACA to generate 4-aminohydrocinnamic acid (4AHCA). The ability of 10 microbial genes for enoate and xenobiotic reductases expressed in Escherichia coli to convert 4ACA to 4AHCA was assessed. A strain producing 2-enoate reductase from Clostridium acetobutylicum (ca2ENR) reduced 4ACA to 4AHCA with a yield of > 95% mol mol and reaction rates of 3.4 ± 0.4 and 4.4 ± 0.6 mM h OD at the optimum pH of 7.0 under aerobic and anaerobic conditions, respectively. This recombinant strain reduced caffeic, cinnamic, coumaric, and 4-nitrocinnamic acids to their corresponding propanoic acid derivatives. We polycondensed 4AHCA generated from biomass-derived 4ACA by dehydration under a catalyst to form high-molecular-weight poly(4AHCA) with a molecular weight of M = 1.94 MDa. This polyamide had high thermal properties as indicated by a 10% reduction in weight at a temperature of T = 394 °C and a glass transition temperature of T = 240 °C. Poly(4AHCA) derived from biomass is stable at high temperatures and could be applicable to the production of high-performance engineering plastics. [ABSTRACT FROM AUTHOR]

Atopic dermatitis (AD) is a skin disorder characterized by filaggrin (FLG) defect. We evaluated sacran’s effects on dust-mite extracts (DME)-induced AD-like disease and also its effect on profilaggrin (proFLG) in a murine model of 2,4- dinitroflurobenze (DNFB)-induced contact hypersensitivity. In the murine AD-like disease model, allergic NC/Nga mice (N = 60) were randomly divided into five treatment groups of 12 animals each: 0.2% and 1%sacran; 0.1% Tacrolimus ; Vaseline and buffer-treated controls. Blood samples were drawn and serum levels of representative Th-1, Th-2 and also Th-17 (IL-17A) cytokines were assayed by Cytometric Bead Array (CBA). In the contact hypersensitivity model, diseased NC/Nga mice (N = 20) were divided into four groups of five mice each [0.05%sacran, 0.05% chondroitin sulfate (CS), 0.5% prednisolone (PD), non-treated control group] and were treated for 14 days. Skin biopsies were performed for the measurement of proFLG-mRNA by real-time PCR. Sacran solutions and 0.1% Tacrolimus reduced disease severity, suppressed histological changes and decreased the serum Th-1 (IFN-γ, TNF-α, IL-2) and Th-2 (IL-4, IL-6, IL-10) cytokines in allergic mice (vs. controls). Additionally, a marked increase of proFLG-mRNA expression was observed in 0.05%sacran group (vs. control 0.05% CS and 0.5% PD groups). Thus, Sacran might be useful as a natural skin barrier enhancer and anti-allergic agent. [ABSTRACT FROM AUTHOR]

Bio-based polybenzoxazoles (PBOs) are prepared by polycondensation of diacid monomer derived from 3-amino-4-hydroxybenzoic acid with a series of aliphatic diamines. Resulting bio-based PBOs have high weight average molecular weight ranging 5.70-7.20 × 10 g/mol and show ultrahigh thermal resistance with T values over 400 °C and T values over 170 °C, which are higher than those of conventional bio-based polymers, polyamides 11 (around 60 °C) or poly(lactic acid) (56 °C). Especially hydrazide group of the bio-based PBO were cyclized to form diazole ring by annealing at 330 °C for 20 min. The resultant PBO show liquid crystalline (LC) behavior to spin fiber in a melting state. The resultant PBO fibers showed high values of Young's modulus and mechanical strength as compared with conventional polymers polyamide 11 and poly(lactic acid) (PLA). [ABSTRACT FROM AUTHOR]

Fully bio-based chitosan derivative was synthesized using 3-benzyl-2,5-diketopiperazine-6-acetic acid (DKP) activated by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. From IR and H NMR spectra, the structure of the bioconjugated chitosan and the quantitative modification were confirmed. Oil-in-water (o/w) emulsion of the obtained product was presented with the various ratios of water and benzene solution. Continuously the obtained o/w emulsions were freeze-dried to produce the mesoporous sponge, depended on the ratio of the water and benzene. These amphiphilic properties were observed by the property of the pendant DKP moieties in chitosan. The pore size in the sponges was controlled in a range from 0.1 to 0.3 μm by changing the solvent ratios. [ABSTRACT FROM AUTHOR]

We have synthesized new bio-based polyureas (PUs) using 4-aminophenylalanine (4-APhe) as a diamine monomer bioavailable by fermentation of genetically modified Escherichia coli. Most of PUs are processable into films or fibers having excellent mechanical properties; mechanical strength at maximum around 150 MPa and strain energy density around 10 J/cm3 at maximum, which means that PU much tougher than those of conventional bioplastics. [ABSTRACT FROM AUTHOR]

Curcumin is one of promising agents to accelerate the wound-healing process. However, the efficacy of curcumin is limited due to its poor water solubility and stability. To enhance the properties of curcumin, 2-hydroxypropyl-γ-cyclodextrin (HP-γ-CyD) can be used through complexation. Recently, we revealed that sacran has the potential to form a hydrogel film (HGF) as a wound dressing material. Therefore, in the present study, we investigated the wound healing ability of curcumin/HP-γ-CyD (Cur/HP-γ-CyD) complex in sacran-based HGF (Sac-HGF). We prepared the Cur/HP-γ-CyD complex in Sac-HGF without surface roughness. Additionally, the amorphous form in the Cur/HP-γ-CyD complex in Sac-HGF were observed. In contrast, the curcumin in Sac-HGF and curcumin/HP-γ-CyD physical mixture in Sac-HGF formed inhomogeneous films due to crystallization of curcumin. Furthermore, HP-γ-CyD played an important role to increase the elastic modulus of the Sac-HGF with high re-swelling ability. The Cur/HP-γ-CyD complex in Sac-HGF maintained antioxidant properties of curcumin. Curcumin was gradually released from the HP-γ-CyD complex in Sac-HGF. Notably, the Cur/HP-γ-CyD complex in Sac-HGF provided the highest wound healing ability in hairless mice. These results suggest that the Cur/HP-γ-CyD complex in Sac-HGF has the potential for use as a new transdermal therapeutic system to promote the wound-healing process. [ABSTRACT FROM AUTHOR]

The size effect of magnetomechanical response of chemically cross-linked disk shaped magnetic elastomers placed on a permanent magnet has been investigated by unidirectional compression tests. A cylindrical permanent magnet with a size of 35 mm in diameter and 15 mm in height was used to create the magnetic field. The magnetic field strength was approximately 420 mT at the center of the upper surface of the magnet. The diameter of the magnetoelastic polymer disks was varied from 14 mm to 35 mm, whereas the height was kept constant (5 mm) in the undeformed state. We have studied the influence of the disk diameter on the stress-strain behavior of the magnetoelastic in the presence and in the lack of magnetic field. It was found that the smallest magnetic elastomer with 14 mm diameter did not exhibit measurable magnetomechanical response due to magnetic field. On the opposite, the magnetic elastomers with diameters larger than 30 mm contracted in the direction parallel to the mechanical stress and largely elongated in the perpendicular direction. An explanation is put forward to interpret this size-dependent behavior by taking into account the nonuniform field distribution of magnetic field produced by the permanent magnet. [ABSTRACT FROM AUTHOR]

A wound dressing is one of the essential approaches for preventing further harm to cutaneous wounds as well as promoting wound healing. Therefore, to achieve ideal wound healing, the development of advanced dressing materials is necessary. Recently, we revealed that a novel megamolecular polysaccharide, sacran, has potential properties as a biomaterial in a physically cross-linked hydrogel film (HGF) for wound dressing application. In this study, to enhance the wound-healing properties of sacran hydrogel film (Sac-HGF) further, we fabricated and characterized novel Sac-HGFs containing cyclodextrins (CyDs). The sacran/α-CyD film (Sac/α-CyD-HGF) and sacran/γ-CyD HGF (Sac/γ-CyD-HGF), but not sacran/β-CyD HGF (Sac/β-CyD-HGF), were well prepared without surface roughness. Powder X-ray diffraction (XRD) patterns of the Sac/γ-CyD-HGFs showed a totally amorphous state compared to that shown by Sac/α-CyD-HGFs. Furthermore, the addition of γ-CyD to Sac-HGFs significantly increased the swelling ratio, porosity, and moisture content of the HGFs, compared to those of the Sac-HGF without CyDs. The Sac/γ-CyD-HGFs were not cytotoxic against NIH3T3 cells, a murine fibroblast cell line. Notably, the Sac/γ-CyD-HGFs significantly improved wound healing in mice, compared to that achieved with the Sac-HGF without γ-CyD. These results suggest that γ-CyD has the potential to promote the wound healing ability of Sac-HGF. [ABSTRACT FROM AUTHOR]