Macromolecular Chains Research Articles

Improving the energy storage efficiency and power density of polymer blend in combination with Ti3C2Tx for energy storage devices

Polymer blend-based dielectrics are extensively used because of their broad working temperature range, quick discharging speed, and high power density. The solution casting approach is used to prepare the PVDF/PMMA- Ti3C2Tx nanocomposite flexible energy storage films. The morphology results show that the composite has a homogeneous and dense microstructure. The structural study shows the composition of thin films and confirms the existence of the PVDF β-phase. The thermal analysis showed 31.36 % crystallinity for 20 wt% of nanocomposite (NCs). The values of band gap energy reduced from 3.07 eV to 2.65 eV with increasing Ti3C2Tx concentration (15 wt%). It was found that the almost high dielectric constant values of (̴205) at 100 Hz and loss of 0.078 were suggestive of increased interfacial polarization. The maximal energy density of the NCs is 1.28 J/cm3, and its power density is 4.86 MW/cm3 for 15 wt% NCs. The conductivities of 15 wt% composite increase to 10−9 –10−7 S.cm−1 at 100 Hz, and then it reaches nearly 10−3 S cm−1 when the frequency is raised to 1 MHz. The 2D MXene nanofiller and PVDF macromolecular chain have an improved interface interaction, which results in excellent complete electrical characteristics. The rise in residual polarization can be inhibited by adding PMMA. In this work, adding 2D Ti3C2Tx MXene to PVDF/PMMA blends offers a viable way to create materials that are highly effective at storing energy in capacitors.

Arc-shaped air layer bioinspired by ginkgo nut to resist high humidity environment for PET fabrics

Developing simple processes and significant effect modification method for polyester (PET) fabrics to resist hygrothermal aging is a formidable challenge. In this study, inspired by the silver mirror phenomenon of natural ginkgo nut, we utilized the pea pod-shaped nanoparticles that zinc oxide (ZnO) was encapsulated in polyhedral oligomeric silsesquioxane (ZnO@POSS), and polydimethylsiloxane (PDMS) to construct stabilized arc-shaped air layer on the PET fabric surface to resist high humidity environment. The round belly structures of pea pod-shaped ZnO@POSS and interlaced physical networks assisted by PDMS on the PET fabrics surface served as the crucial roles to capture and retain air, resulting in the capacity of the arc-shaped air layer was significantly larger than other microstructures underwater. The water vapor was prevented from entering the fabric interstices that the self-catalytic hydrolysis behavior of PET macromolecular chains was efficiently restrained, and the strength retention of PET fabric was significantly improved from 45 % to 89 % after accelerated hygrothermal aging test (60 °C, 80 % RH, 600 h). This work represents a simple and effective approach to improve the durability for PET fabrics in high humidity environments.

Supramolecular blends of C-alkylpyrogallol[4]arenes and polytetrahydrofurans

A small series of the amphiphilic macrocycles – C-alkylpyrogallol[4]arenes has been synthesized and examined by single crystal X-ray analysis which showed the formation of two supramolecular arrangements depending on solvent used for crystallization, i.e., multilayered motif and hexameric capsule. Those structural findings provided an insight into blends prepared from aforementioned macrocycles and various polytetrahydrofurans (polyTHFs). Thus, 1:1 wt ratio mixtures were obtained and investigated by combination of Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). As it turned out, the viscosity of these blends was increased compared to starting materials, which imply that pyrogallol[4]arenes can be successfully utilized as supramolecular cross-linkers enhancing H-bonding between adjacent macromolecular chains. As the major difference between compounds synthesized is the length and geometry of their respective alkyl side chains attached directly to macrocyclic core, i.e., n-propyl- and cyclohexyl- vs. n-dodecyl-, it seemed likely that even insignificant increase in their hydrophobicity can induce high order aggregation of nanoparticles in the slurries, thus affecting their viscosity. Overall, material viscoelastic properties are tunable at macroscopic level by choosing particular pyrogallol[4]arene/solvent combination and adjusting the temperature, which may be advantageous for the design of hybrid materials.

Overcoming strength-ductility and functional period-degradability tradeoffs: Multifunctional biodegradable polyesters with ionic cluster skeleton and PDMS skin

To overcome the strength-ductility and functional period-degradability tradeoffs of biodegradable polyesters, we proposed a nanophase structure design strategy to construct a soft-hard dual phase in poly(butylene succinate) (PBS) copolymers by simultaneously introducing polydimethylsiloxane (PDMS) and isophthalate-5-sulfonate (SIPM) on PBS macromolecular chains to improve the stiffness, toughness, and multifunctionality. The high-resolution transmission electron microscope (HR-TEM) and energy dispersive X-Ray spectroscopy (EDX) tests indicated that PBS copolymers possessed continuous “ionic cluster skeleton” and “PDMS skin”. The hybrid liquid state theory and self-consistent field approach for copolymers further demonstrated the mechanism of microphase separation for PDMS blocks and SIPM segments. The copolymers showed excellent yield strength of 52 MPa, great impact strength of 171 J/m, large extensibility of 491 %, and long functional period in the acidic environment. The novel stereo nanostructure endowed the materials with advanced multifunctions that can be applied in various applications, such as the biomedical field and flexible electronic devices. Compared with PBS, copolymers possessed excellent in vitro attachment and proliferation of MC3T3-E1 cells. Furthermore, the synergistic effect of the ionic skeleton and PDMS skin improved the ionic conductivity of the materials. The copolymer film was innovatively employed as anion-exchanging separators of supercapacitors with acid-organized electrolytes. It has been testified that this newly designed strategy of a novel stereo nanophase structure was efficient in endowing the biodegradable polyesters with excellent combined properties and multifunctions.

Preparation and characterization of crystalline poly(L‐lactic acid)/silica nanocomposite films with high ductility and gas barrier properties

AbstractIncorporating inorganic particles is a common approach to preparing polymeric materials with desirable physical properties and processability. However, this often results in increased brittleness, necessitating methods to improve melt strength and toughness. In this study, in situ polymerization was employed to functionalize silica nanoparticles with the silane coupling agent (3‐aminopropyl) triethoxysilane (APTES) as a core. A flexible chain segment, poly(butylene itaconate) (PBI), was then introduced as a “rubbery” intermediate layer, resulting in a core‐shell structure of poly(L‐lactic‐co‐butanediol itaconate) nano‐silica copolymer films (PLBISiO2) with both branched and “rubbery” structures. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) confirmed the formation of macromolecular chains, with the molecular weight (Mn) of PLBI increasing from 59,638 to 74,306 g/mol. This significant increase supports the “rubbery” core‐shell structure. When 0.5% SiO2 was added, the T5% of the film increased by 40°C, significantly improving thermal stability. Additionally, the elongation at break increased to 265.7%, while retaining the original tensile strength. Dynamic rheology experiments further confirmed the generation of branched or “rubbery” core‐shell structures, and a doubling of gas barrier properties was observed with increased silica nanoparticles, suggesting potential applications in food packaging or biopharmaceuticals.Highlights Nanocomposites with core‐shell structure and improved mechanical properties. Dynamic rheology experiments confirmed the formation of the core‐shell structure. Significantly improved gas barrier properties due to core‐shell structure.

Structural Rheology in the Development and Study of Complex Polymer Materials.

The progress in polymer science and nanotechnology yields new colloidal and macromolecular objects and their combinations, which can be defined as complex polymer materials. The complexity may include a complicated composition and architecture of macromolecular chains, specific intermolecular interactions, an unusual phase behavior, and a structure of a multi-component polymer-containing material. Determination of a relation between the structure of a complex material, the structure and properties of its constituent elements, and the rheological properties of the material as a whole is the subject of structural rheology-a valuable tool for the development and study of novel materials. This work summarizes the author's structural-rheological studies of complex polymer materials for determining the conditions and rheo-manifestations of their micro- and nanostructuring. The complicated chemical composition of macromolecular chains and its role in polymer structuring via block segregation and cooperative hydrogen bonds in melt and solutions is considered using tri- and multiblock styrene/isoprene and vinyl acetate/vinyl alcohol copolymers. Specific molecular interactions are analyzed in solutions of cellulose; its acetate butyrate; a gelatin/carrageenan combination; and different acrylonitrile, oxadiazole, and benzimidazole copolymers. A homogeneous structuring may result from a conformational transition, a mesophase formation, or a macromolecular association caused by a complex chain composition or specific inter- and supramolecular interactions, which, however, may be masked by macromolecular entanglements when determining a rheological behavior. A heterogeneous structure formation implies a microscopic phase separation upon non-solvent addition, temperature change, or intense shear up to a macroscopic decomposition. Specific polymer/particle interactions have been examined using polyethylene oxide solutions, polyisobutylene melts, and cellulose gels containing solid particles of different nature, demonstrating the competition of macromolecular entanglements, interparticle interactions, and adsorption polymer/particle bonds in governing the rheological properties. Complex chain architecture has been considered using long-chain branched polybutylene-adipate-terephthalate and polyethylene melts, cross-linked sodium hyaluronate hydrogels, asphaltene solutions, and linear/highly-branched polydimethylsiloxane blends, showing that branching raises the viscosity and elasticity and can result in limited miscibility with linear isomonomer chains. Finally, some examples of composite adhesives, membranes, and greases as structured polymeric functional materials have been presented with the demonstration of the relation between their rheological and performance properties.

Natural resin-derived urushiol-based phosphorylation derivative towards flame-retardant and mechanically strong epoxy resin

Biobased flame retardants have attracted great attention owing to their environmental friendliness and easy availability. Urushiol, extracted from natural resin-raw lacquer, has been capped with diphenylphosphoryl chloride to afford a biobased flame retardant, namely urushiol-based phosphonate (U-DC). As an additive this material is effective in reducing flammability while maintaining good mechanical strength for epoxy resins (EP). Impressively, an EP/9 %U-DC blend exhibits a UL-94 V-0 rating, and an LOI of 37.1 % for combustion. Further, compared to that for EP, the peak heat release rate (pHRR) and total heat release (THR) for the EP/9 %U-DC blend was lower by 40.5 % and 26.6 %. Through analysis of volatile products formed and char residue produced during polymer degradation, a mode of flame retardant action for U-DC has been proposed. Further, EP/U-DC blends display better mechanical properties than those of unmodified EP. Tensile strength of EP containing 7 wt% U-DC (81.6 MPa) is greater than that for unmodified EP (64.4 MPa). This may be ascribed to the presence of abundant rigid benzene units in U-DC and chain entanglement between the long side chain of U-DC and the epoxy macromolecular chain. These observations provide a basis for the utilization of new urushiol derivatives in the production of high-performance EP.

Self-passivation/self-delivery/self-healing anticorrosion polymer coating for marine applications

Corrosion of steel in the marine environment greatly reduces their service life. Polymeric coatings are the most popular anticorrosion technology, but seawater penetration cannot be prohibited because of the distinct stacking structure of the macromolecular chains. In this context, a novel anticorrosive hyperbranched polyurethane-based coating with dopamine (DOPA) at the terminals is prepared herein. The built-in DOPA is able to capture the iron ions released from the corroded substrate and form DOPA-Fe3+ complexation, which further cooperates with the surrounding seawater and imparts self-passivation, self-delivery and self-healing capabilities to the coating. Under the joint action of these measures, the corrosion of tinplate (serving as the steel model) is reduced to a record-low level (corrosion current = 1 × 10−9 A cm−2, corrosion rate = 1 × 10−5 mm year−1). Conceptually, the present dynamic active anticorrosion strategy greatly outperforms the traditional static passive approach, and turns the unfavorable but unavoidable seawater into a favorable factor, which paves the way for the development of long-lasting marine coatings.

Fabricating epoxy vitrimer with excellent mechanical and dynamic exchange properties via network topology design

Epoxy vitrimers are a novel type of environmentally friendly materials that possess exceptional properties, including self-healing, recyclability, and reprocessability. They offer a solution to the issue of traditional thermosetting epoxy resins, which are not recyclable. However, the incorporation of dynamic bonds typically results in a decrease in mechanical properties. Therefore, achieving a balance between the mechanical properties and dynamic exchange capability is crucial. In this work, a series of epoxy resin systems with various topological network characteristics were prepared by adjusting the proportions of bisphenol A epoxy resin (E51) and polyethylene glycol diglycidyl ether (EGDGE) epoxy resins in combination with a curing agent containing vinylogous urethane (VU) dynamic bonds. Through further study, we found that with the increase of E51 content, the cross-linking density of the network gradually increased, and the flexibility of the macromolecular chains decreased (favorable for enhancing the material's mechanical performance). Simultaneously, the free volume of the network gradually increased, and the tightness of the macromolecular chains decreased (favorable for improving the material's dynamic exchange ability). These two effects combined to make E51-40 exhibit the lowest activation energy for dynamic covalent bond exchange and the lowest topological transition temperature. Compared to E51-0, the tensile strength and glass transition temperature of E51-40 were improved by 22.23 % and 25.30 %, respectively. After remoulding experiment at 140 °C for 1h, the material exhibited a high tensile strength recovery of 91.34 %. Therefore, starting from the design of molecular structure, adjusting the network topology is an effective means to balance the mechanical and dynamic exchange properties of epoxy vitrimers. This provides experimental guidance and theoretical insights for designing high-performance epoxy vitrimer materials.

Semi‐aromatic poly(m‐xylylene adipamide‐co‐isophthalamide) copolyamides (MXD6/I): Effect of isophthalic acid on the thermal, crystallization, mechanical, and barrier properties

AbstractSemi‐aromatic nylon MXD6 shows superior mechanical strength and gas barrier properties. To improve its toughness and get sight into its excellent properties, a series of poly(m‐xylylene adipamide‐co‐isophthalamide) (MXD6/I) random copolyamides were synthesized using adipic acid, isophthalic acid (IPA) and m‐xylylene diamine as monomers via direct melt polycondensation. The effect of IPA content on the thermal, crystallization, heat resistant, mechanical, and barrier properties of the copolyamides were systematically investigated. The results showed that the increase of IPA content from 0 to 12 mol% resulted in a decrease in the melting point of the copolyamides from 238 to 217°C but the glass transition temperature (Tg) increased from 88 to 105°C. Correspondingly, the Vicat softening temperature decreased from 199.2 to 172.5°C. The crystallization rate of the copolyamides significantly decreased with the increase of the IPA content. The copolyamides had improved elongation and rupture energy and decent oxygen barrier properties with the introduction of IPA. It is expected that this study would guide design of MXD6 macromolecular chain structure to prepare high‐performance MXD6 materials.

One-Pot Preparation of Ratiometric Fluorescent Molecularly Imprinted Polymer Nanosensor for Sensitive and Selective Detection of 2,4-Dichlorophenoxyacetic Acid.

The development of fluorescent molecular imprinting sensors for direct, rapid, and sensitive detection of small organic molecules in aqueous systems has always presented a significant challenge in the field of detection. In this study, we successfully prepared a hydrophilic colloidal molecular imprinted polymer (MIP) with 2,4-dichlorophenoxyacetic acid (2,4-D) using a one-pot approach that incorporated polyglycerol methacrylate (PGMMA-TTC), a hydrophilic macromolecular chain transfer agent, to mediate reversible addition-fragmentation chain transfer precipitation polymerization (RAFTPP). To simplify the polymerization process while achieving ratiometric fluorescence detection, red fluorescent CdTe quantum dots (QDs) and green fluorescent nitrobenzodiazole (NBD) were introduced as fluorophores (with NBD serving as an enhancer to the template and QDs being inert). This strategy effectively eliminated background noise and significantly improved detection accuracy. Uniform-sized MIP microspheres with high surface hydrophilicity and incorporated ratiometric fluorescent labels were successfully synthesized. In aqueous systems, the hydrophilic ratio fluorescent MIP exhibited a linear response range from 0 to 25 μM for the template molecule 2,4-D with a detection limit of 0.13 μM. These results demonstrate that the ratiometric fluorescent MIP possesses excellent recognition characteristics and selectivity towards 2,4-D, thus, making it suitable for selective detection of trace amounts of pesticide 2,4-D in aqueous systems.

Preparation and Properties of GMS/HTSF-Modified Waterborne Polyurethane Fluorine-Free Waterproof and Breathable Film.

Developing a fluorine-free, durable, high-performance waterproof breathable film for fabrics remains a formidable challenge. In this paper, a strategy for the preparation of fluorine-free, durable, and high-efficiency fabric waterproof and breathable membranes using glyceryl monostearate (GMS)/double-ended hydroxy silicone oil (HTSF)-modified waterborne polyurethane was proposed. The orderly orientation of GMS and HTSF gives the fabric excellent water-repellent properties, and the polyurethane macromolecular chain ensures strong adhesion of long-chain alkanes and silicones to the fabric surface. In this paper, the effects of different GMS contents on the stability, chemical structure, particle size, viscosity, water absorption performance, surface morphology, and XPS of a waterborne polyurethane fluorine-free waterproof and breathable membrane (GHWPU) were studied. At the same time, the application properties of GHWPU-treated fabrics, such as waterproof performance, antifouling performance, surface energy, morphology, and air permeability, were discussed. Through the analysis of SEM and XPS, it was found that the folds on the surface of the film were more and more orderly with the increasing content of GMS, and this orderly distribution of water-repellent groups endowed the film with excellent water-repellent ability. When the GMS content was 28 wt %, the finished fabrics had excellent comprehensive properties such as static contact angle of 141.6°, hydrostatic pressure of 96.7 KPa, resistance to more than 30 washes, and air permeability of 119.3 mm/s.

Polymerization‐Induced Emission and Specific Detection to Cu2+ Ions of Polyacrylates with Morpholine Structure

AbstractIn this investigation, the fluorescent poly(N‐hydroxyethyl morpholine acrylate) (PHEMA) and poly(N‐hydroxypropyl morpholine acrylate) (PHPMA) are prepared and applied as fluorescent probes for the specific detection of Cu2+ ions. Far different from the non‐fluorescent monomer, PHEMA and PHPMA emit a strong fluorescence at 410 nm due to the intramolecular aggregation of morpholine structures along macromolecular chains in the polymerization, indicating polymerization‐induced emission (PIE). The fluorescent emission of PHPMA shows the dependence on external factors including solution concentration, excitation wavelength, solvent, and pH value. PHPMA specifically detects Cu2+ ions even in the presence of 16 common metal ions and 6 anions, with an LOD of 0.077 µM. In the fluorescent quenching, the O atom from ─C═O and N atom from morpholine moiety on the PHPMA chain participate in the complexation with Cu2+ ions with the ratio of the structural unit and Cu2+ ion of 2:1, leading to the dynamic quenching of PHPMA solution. As for the application, PIE‐active PHPMA is easily made into a portable semi‐quantitative filter paper with recyclability. In brief, the PIE‐active PHPMA synthesized in this study can be used as a promising material for the specific detection of Cu2+ ions in industry, agriculture, and medicine fields.

Evolution mechanism of organic macromolecular structure during lignite pyrolysis

Understanding the mechanisms governing coal pyrolysis reactions, particularly in relation to the coal macromolecular structure, is crucial for improving energy efficiency and facilitating the transition of coal into a clean energy source. This study employs cutting-edge techniques, such as High-Resolution Transmission Electron Microscopy (HRTEM) and Thermogravimetric Analysis coupled with Fourier Transform Infrared Spectroscopy and Mass Spectrometry (TG–FTIR–MS), to analyze lignite and its residual solid samples subjected to pyrolysis across a range of temperatures from 300 °C to 1100 °C. The variational characteristics of the macromolecular structure during coal pyrolysis are examined. Utilizing molecular dynamics simulations, we analyze the evolution mechanism of the macromolecular carbon structure of organic matter during the coal pyrolysis process. The results show that the pyrolysis can be divided into three distinct phases: activation (30–300 °C), pyrolysis (300–650 °C), and condensation (650–1200 °C). During these phases, the coal structure undergoes complex transformations, including folding, twisting, shedding of small molecular side chains, and breaking of macromolecular side chains, ultimately leading to the directional arrangement of structural fragments. The structural units initially undergo decomposition, followed by growth and alignment in a certain direction. The spatial distribution of aromatic structural units evolves from local ordering to complete disordering, culminating in larger-scale, three-dimensional ordering. The order of bond breaking within the macromolecular structure of lignite pyrolysis is: oxygen-containing functional groups (such as C–O and COOH) > aliphatic structure (N–C and C–C) > aromatic structure (CC). By uncovering the reaction intermediates and pathways involved in lignite pyrolysis, this research provides a comprehensive quantitative description of the coal pyrolysis process. These insights offer invaluable theoretical support for the industrial-scale pyrolysis of coal, paving the way for more efficient and sustainable utilization of this crucial energy resource.

An Algorithm for Computing Entanglements in an Ensemble of Linear Polymers

AbstractThe entanglement length plays a key role in deciding many important properties of thermoplastics. A number of computational techniques exist for the determination of entanglement length. In Ahmad et al.,[1] a method is proposed that treats a macromolecular chain as a 1D open curve and identifies entanglements by computing the linking number between two such interacting curves. If the curves wind around each other, a topological entanglement is detected. However, the entanglement length that is measured in experiments is assumed to be between rheological entanglements, which are clusters of such topological entanglements that collectively anchor the interacting chains strongly. In this article, the method of clustering topological entanglements into rheological ones is further elaborated and the robustness of the method is assessed. It is shown that this method estimates an entanglement length that depends on the forcefield chosen and is reasonably constant for chain lengths longer than the entanglement length. For shorter chain lengths, the method returns an infinite value of entanglement length indicating that the sample is unentangled. Moreover, in spite of using a geometry‐based algorithm for clustering topological entanglements, the estimated entanglement length retains known empirical connections with physical attributes associated with the ensemble.

Harnessing Cytosine for Tunable Nanoparticle Self-Assembly Behavior Using Orthogonal Stimuli.

Nucleobases control the assembly of DNA, RNA, etc. due to hydrogen bond complementarity. By combining these unique molecules with state-of-the-art synthetic polymers, it is possible to form nanoparticles whose self-assembly behavior could be altered under orthogonal stimuli (pH and temperature). Herein, we report the synthesis of cytosine-containing nanoparticles via aqueous reversible addition-fragmentation chain transfer polymerization-induced self-assembly. A poly(N-acryloylmorpholine) macromolecular chain transfer agent (mCTA) was chain-extended with cytosine acrylamide, and a morphological phase diagram was constructed. By exploiting the ability of cytosine to form dimers via hydrogen bonding, the self-assembly behavior of cytosine-containing polymers was altered when performed under acidic conditions. Under these conditions, stable nanoparticles could be formed at longer polymer chain lengths. Furthermore, the resulting nanoparticles displayed different morphologies compared to those at pH 7. Additionally, particle stability post-assembly could be controlled by varying pH and temperature. Finally, small-angle X-ray scattering was performed to probe their dynamic behavior under thermal cycling.

Imparting Ultrahigh Strength to Polymers via a New Concept Strategy of Construction of up to Duodecuple Hydrogen Bonding among Macromolecular Chains.

Interconnecting macromolecules via multiple hydrogen bonds (H-bonds) can simultaneously strengthen and toughen polymers, but material synthesis becomes extremely difficult with increasing number of H-bonding donors and acceptors; therefore, most reports are limited to triple and quadruple H-bonds. Herein, this bottleneck is overcome by adopting a quartet-wise approach of constructing H-bonds instead of the traditional pairwise method. Thus, large multiple hydrogen bonds can be easily established, and the supramolecular interactions are further reinforced. Especially, when such multiple H-bond motifs are embedded in polymers, four macromolecular chains-rather than two as usual-are tied, distributing the applied stress over a larger volume and more significantly improving the overall mechanical properties. Proof-of-concept studies indicate that the proposed intermolecular multiple H-bonds (up to duodecuple) are readily introduced in polyurethane. A record-high tensile strength (105.2MPa) is achieved alongside outstanding toughness (352.1 MJ m-3), fracture energy (480.7 kJ m-2), and fatigue threshold (2978.4 J m-2). Meantime, the polyurethane has acquired excellent self-healability and recyclability. This strategy is also applicable to nonpolar polymers, such as polydimethylsiloxane, whose strength (15.3MPa) and toughness (50.3 MJ m-3) are among the highest reported to date for silicones. This new technique has good expandability and can be used to develop even more and stronger polymers.

Enhanced Stability-Based Hydroxymethyl Cellulose/Polyacrylamide Interpenetrating Dual Network Hydrogel Electrolyte for Flexible Yarn Zinc-Ion Batteries

As the field of wearable electronics continues to boom, the demand for flexible energy storage devices continues to grow. However, the development of soft energy supply devices with excellent stability is still a challenging task. Traditional hydrogel electrolytes are prone to mechanical deformation, which makes it difficult to maintain the functional stability of flexible yarn due to its short battery life and low wear resistance. Here, we developed a reversible energy-dissipating dual-network hydrogel electrolyte. The hydroxymethyl cellulose (CMC)/polyacrylamide (PAM) hydrogel electrolyte has a tensile deformation of 2700% and a high ionic conductivity of 6.37 × 10−2 S cm−1. The specific capacity of the assembled CMC/PAM-based yarn cell was 170 μAh cm−1 at 1 mA cm−1 and 73.14% after 100 cycles. The excellent performance is attributed to the crosslinked double network structure, in which the introduction of carboxyl groups is conducive to the improvement of hydrophilicity and ionic conductivity. The hydrogen bond and reversible CMC macromolecular chain can be restored after stress relief, which greatly improves the toughness of the material. Even under different bending angles and repeated bending conditions, zinc yarn batteries still have outstanding mechanical properties and cycle stability (71.28% specific capacity after 100 cycles), showing broad application prospects in wearable smart textiles.

Design and evaluation of fluorescent chitosan-starch hydrogel for drug delivery and sensing applications

Composite bio-based hydrogels have been obtaining a significant attention in recent years as one of the most promising drug delivery systems. In the present study, the preparation of composite chitosan-starch hydrogel using maleic acid as a cross-linker was optimized with the help of response surface methodology. The synthesized hydrogel was fluorescent owing to clustering of large number of functional groups. Different analytical techniques, including XRD, FTIR, SEM, XPS, fluorescence and BET were utilized to characterize the prepared hydrogel. XRD analysis confirmed the formation of non-crystalline hydrogel with random arrangement of macromolecular chains. The composite hydrogel exhibited good swelling percentage with pH sensitivity, hemocompatibility and degradability. BET analysis confirmed that the variation in concentration of crosslinker significantly influences the pore volume of the hydrogel. The synthesized composite chitosan-starch hydrogel was utilized as a prospective candidate for controlling drug release. Cefixime as a model drug was loaded onto the synthesized hydrogel utilizing the swelling diffusion method. SEM micrographs showed uniform distribution of drug molecules in the drug loaded hydrogel. In vitro drug release experiments indicated the swelling dependent drug release behaviour of chitosan-starch hydrogel with higher drug release at pH 7.4 (93.08 %) compared to pH 1.2 (67.85 %). The composite chitosan-starch hydrogel was able to prolong and control the drug release up to 12 h. The drug release from the hydrogel followed Korsmeyer-Peppas and Makoid-Banakar model with Fickian diffusion mechanism. Further, the composite hydrogel displayed excitation dependent fluorescence emission with most intense blue emission band at 425 nm with an excitation wavelength of 350 nm. The inclusion of cefixime drug in the hydrogel matrix significantly reduced the fluorescence intensity; the decrease was linearly correlated to the concentration of the drug. Moreover, the fluorescence emission the chitosan-starch hydrogel was found to be dependent upon pH. The synthesized hydrogel is expected to be a potential candidate for controlled drug release as well as for fluorescent sensing applications.

Experimental and simulation studies of degraded EPDM composite in the coupled gamma radiation-thermal environments

The degradation behaviors, mechanisms and compatibility are not well understood and hard to be harnessed for EPDM composite in the coupled gamma radiation-thermal environments. This contribution performs a thorough study accordingly with 0 ∼ 200 kGy dose under temperatures varying from room temperature to 90 °C in N2/O2 mixture atmosphere. Radiation-thermal aging leads to annealing effect and chemi-crystallization that rebuilds the semi-crystalline structure and invokes competitive filler migration, reconfiguration and loss. Crosslinking reactions prevail the scission during the investigated conditions. However, the surface oxidation and damage are not severe. In-situ nondestructive gas-phase FTIR sensitively find the formed various gaseous products, whose generation kinetics behaviors are temperature and dose dependent. Most surprisingly, the radiolysis caused carbonyl sulfide and carbon disulfide are discovered with indispensable gamma radiation, which manifest temperature reined conversion thermodynamics and kinetics behavior. The qualitative and quantitative analysis of gas products is also validated by GC and GC-MS tests. The evolved semi-crystalline structure, macromolecular chain network and filler network significantly impact the mechanical property, but the barrier property and hydrophobic property are slightly influenced. The inverse temperature effect occurred at 50 °C for the mechanical properties, which show abnormal rejuvenation behavior due to the counteraction between aging induced change in molecular structure, aggregation structure and filler reconfiguration, migration and loss. The multiscale structure-property-behavior relationships possess good interdependency, indicating the main aging mechanism and failure mode are almost invariant. By ReaxFF simulation, the complex degradation mechanism for EPDM composite at atomic scale is revealed for the first time.