Pickering emulsions with high ionic strength resistance stabilized by pea protein isolate-polyglycerol conjugate particles with good biocompatibility.

Among various biopolymers, protein particles are widely used for stabilizing Pickering emulsions, yet their emulsifying ability are easily influenced by the ion concentration, pH, and high temperatures. To address these challenges, this study utilized chemical modification to prepare pea protein isolate-polyglycerol (PPI-PG) conjugates by Schiff-base reaction. Compared with other chemical modifications, this method produces conjugate particles with excellent biocompatibility, capable of promoting cell proliferation by up to 177 %. These conjugates showed improved dispersibility, with diffusion coefficients 3.5 times greater than pure PPI, and the isoelectric points shift from pH 4.6 to pH 1.5, which contribute to the pH stability of emulsions (pH 3-9). Additionally, the anisotropic nature of the conjugate particles, with a three-phase contact angle close to 90°, make particles need more energy for detachment from the oil-water interface, leading to good thermal stability of emulsion (80 °C, 48 h). Notably, after conjugation, these particles rely more on PG chains for dispersibility, which are less affected by ions, resulting in emulsions with high ionic strength resistance (3000 mM). Furthermore, the prepared Pickering emulsion demonstrates remarkable antioxidative properties (only a 10 % decrease), indicating widely potential applications in food, cosmetics, and pharmaceutical sectors.

Ultra-stable pickering emulsion stabilized by anisotropic pea protein isolate-fucoidan conjugate particles through Maillard reaction.

Bio-based emulsifiers hold significant importance in various industries, particularly in food, cosmetics, pharmaceuticals and other related fields. In this study, pea protein isolate (PPI) and fucoidan (FUD) were conjugated via the Maillard reaction, which is considered safe and widely used in the preparation of food particle. The PPI-FUD conjugated particles exhibit an anisotropic non-spherical structure, thereby possessing a high detachment energy capable of preventing emulsion coalescence and Ostwald ripening. Compared to emulsions previously prepared in other studies (< 500 mM), the Pickering emulsion stabilized by PPI-FUD conjugate particles demonstrates outstanding ionic strength resistance (up to 5000 mM). Furthermore, when encapsulating curcumin, the Pickering emulsion protects the curcumin from oxidation. Additionally, the formulated emulsions demonstrated the capability to incorporate up to 60 % (v/v) oil phase, revealing remarkable performance in terms of storage stability, pH stability, and thermal stability.

High transparency, water vapor barrier and antibacterial properties of chitosan/carboxymethyl glucan/poly(vinyl alcohol)/nanoparticles encapsulating citral composite film for fruit packaging.

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.

Soft-hard dual nanophases: a facile strategy for polymer strengthening and toughening.

Polymers often face a trade-off between stiffness and extensibility-for example, toughening rigid polymers by incorporating plasticizers or flexible polymers leads to strikingly decreased stiffness. Herein, we circumvent this long-standing tricky dilemma in materials science via constructing soft-hard dual nanophases in polymers. As-fabricated dual-nanophase PLA shows a high yield strength of 69.1 ± 4.4 MPa, a large extensibility of 279.1 ± 25.5%, and a super toughness of 115.2 ± 10.3 MJ m-3, which are 1.2, 48 and 82 times, respectively, those of neat PLA. Combined high stiffness, large ductility, and super toughness are unprecedented for PLA and enable bio-sourced PLA to replace petroleum-based resins such as PP, PET and PC. Besides, soft-hard dual nanophases in polymers are rarely reported due to significant constraints in terms of modifier dispersion/aggregation, interfacial regulation, and processing difficulties. The construction strategy described herein, combining controlled annealing and a well-designed plasticizer, can efficiently construct soft-hard dual nanophases in polymers, which will greatly advance the nanostructure design of polymers. More importantly, the proposed strategy for materials design will be widely applicable to industrial manufacturing in terms of nanophase construction and interfacial optimization due to the simplicity and availability at a large scale. We envision that this work offers an innovative and facile strategy to circumvent the trade-off between stiffness and extensibility and to advance the nanostructure design of high-performance polymers in a manner applicable to industrial manufacturing.

A Self-Assemble Supramolecular Film with Humidity Visualization Enabled by Clusteroluminescence.

Clusteroluminescence (CL) has recently gained significant attention due to its unique through-space interactions associated with a high dependence on the aggregation of subgroups. These distinct features could easily transform the stimuli into visual fluorescence and monitor the fluctuation of the environment but have not received sufficient attention before. In this work, supramolecular films are designed based on the neutralization reaction of anhydride groups and the self-assembly of dynamic covalent disulfide bonds in NaOH aqueous solution. The self-assembly of hydrophilic carboxylate chromophores and hydrophobic disulfide-containing five-membered rings could be observed by the variation of the aggregation state of carboxylate in CL. Furthermore, the dynamic cross-linking films obtained with water-sensitive carboxylate chromophores could alter the aggregation distance stimulated by surrounding water vapor, causing the emission wavelength to change from 534 to 508 nm by varying the relative humidity. This work not only provides an approach to monitor the self-assembly of clusteroluminogens but also offers new strategies for designing stimuli-responsive materials that utilize the intrinsic features of CL.

Regulating Electrostatic Interactions toward Thermoresponsive Hydrogels with Low Critical Solution Temperature.

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.

Rapid Preparation of Highly Stretchable and Fast Self-Repairing Antibacterial Hydrogels for Promoting Hemostasis and Wound Healing.

Hydrogel dressings have emerged as a vital resource in wound management, offering several advantages over conventional wound dressing materials. Their inherent biocompatibility, ability to replicate the native extracellular matrix, and capacity to provide an ideal environment for cell survival make them particularly valuable. Nevertheless, the mechanical properties of many hydrogel dressings are an area that warrants improvement, as it currently constrains their application range. This limitation is especially evident when skin wounds are addressed in highly active or easily scratched areas. In this study, we present the development of a highly stretchable self-repairing hydrogel by cross-linking poly(vinyl alcohol) (PVA) through dynamic boron ester bonds, coupled with the hydrogen bonding of carboxymethyl cellulose sodium (CMC) via an efficient one-pot method without adding any catalyst. This innovative PVA/CMC hydrogel exhibited remarkable antibacterial properties achieved through the incorporation of bergamot oil, which was dispersed in a ß-cyclodextrin solution. The hydrogel's elongation at the point of rupture reached an impressive 1910%, and it was capable of rapid self-healing in just 3 min upon bonding. Additionally, the hydrogel demonstrated excellent hemostatic properties, effectively mitigating blood loss and exudation. In vivo wound models have shown that PVA/CMC significantly expedites wound healing by reducing bacterial infections, inflammatory responses, and blood loss and by promoting collagen deposition. In summary, this research provides crucial insights into its potential as an advanced wound dressing material, particularly well-suited for addressing wounds in places with frequent activities or easy scratches.

Branched Copolymers with Tunable Clusteroluminescence in High Quantum Yield.

A novel type of fluorescence without large conjugated structures called clusteroluminescence (CL) has attracted a great deal of attention in recent years. Despite its many advantages, the emerging CL still encounters difficulties of low quantum yield (QY) and preliminary mechanisms. In this work, the branched structure was introduced into poly(maleic anhydride-alt-vinyl acetate) by chain transfer monomer. The emission wavelength of the branched copolymers is red-shifted with the increase of branching degree, and the absolute QY of solids can reach up to 29.87%. Further characterizations reveal that the branched structure can improve the flexibility of polymer chains, thereby promoting the intrachain interactions of subgroups. Furthermore, in the case of branched anhydride copolymers, the equilibrium between intrachain interactions and nonradiative transitions holds a crucial significance in determining the QY. This endeavor not only offers new insights into the mechanism of CL but also presents a novel approach to surmount the low QY of anhydride copolymers, thus broadening the horizons of CLgens to unexplored domains.

Skin-Inspired Patterned Hydrogel with Strain-Stiffening Capability for Strain Sensors.

Flexible materials with ionic conductivity and stretchability are indispensable in emerging fields of flexible electronic devices as sensing and protecting layers. However, designing robust sensing materials with skin-like compliance remains challenging because of the contradiction between softness and strength. Herein, inspired by the modulus-contrast hierarchical structure of biological skin, we fabricated a biomimetic hydrogel with strain-stiffening capability by embedding the stiff array of poly(acrylic acid) (PAAc) in the soft polyacrylamide (PAAm) hydrogel. The stress distribution in both stiff and soft domains can be regulated by changing the arrangement of patterns, thus improving the mechanical properties of the patterned hydrogel. As expected, the resulting patterned hydrogel showed its nonlinear mechanical properties, which afforded a high strength of 1.20 MPa while maintaining a low initial Young's modulus of 31.0 kPa. Moreover, the array of PAAc enables the patterned hydrogel to possess protonic conductivity in the absence of additional ionic salts, thus endowing the patterned hydrogel with the ability to serve as a strain sensor for monitoring human motion.

In situ synthesis of silver nanoparticles with controllable size distribution and high content in bagasse nanocellulose hydrogel.

Developing an environment-friendly preparation method for silver nanoparticles (AgNPs) composite is significant. However, it remains challenges in size adjustment and content improvement of AgNPs. Here, the NaIO4 oxidation and TEMPO-mediated oxidation were applied to bagasse pulp to prepare nanocellulose (NC) with both carboxyl and aldehyde groups. The aldehyde content of NC could be adjusted in the range of 0.21-1.45 mmol/g by different NaIO4 oxidation times. When the carboxyl groups were protonated, NC with a high length-diameter ratio could construct stable hydrogels in a low concentration at 0.5 wt%. The NC hydrogels showed excellent in situ synthesis ability of AgNPs with abundant pore structure. By regulating the carboxyl group content of NC, the size distribution of synthesized AgNPs could be controlled in the range of 7.14-28.6 nm with high content of 6.79-11.0 %. The NC/AgNPs composite hydrogel exhibited high catalytic degradation activity for 4-nitrophenol and antibacterial activity. This approach for constructing NC hydrogel paves the way for AgNPs composite products with adjustable sizes and high contents.

Photothermal-Driven Polymer for a Smart Window with Adaptive Solar Modulation.

Although the thermochromic smart windows with adjustable sunlight transmittance to achieve energy savings are gradually improving, they are still difficult to use, limited by their unreasonable thermal response temperature, slow switching time, and poor durability. Here, we demonstrate a dual-function hybrid thermoresponsive smart window device (CPH) by trapping the phase-change polyHEA-HDA polymer (HEA = hydroxyethyl acrylate, HDA = hexadecyl acrylate) and polydopamine@CsxWO3 (PDA@CWO) core-shell nanoparticles within glasses. The introduced PDA@CWO nanoparticles substantially increase the energy transformation efficiency of solar energy to heat due to their outstanding photothermal conversion. When the temperature increases above the phase-transition temperature of polyHEA-HDA polymer, the copolymer components in the composite material undergo a reversible crystalline-amorphous transition, which enables the transformation of the whole smart window from transparency to opaque in a low ambient temperature. The light transmittance in the solar range can be dynamically modulated between 54.8 and 22.9% with a low ambient temperature while maintaining acceptable visible light transparency and effective UV shielding. A model house testing proves an indoor temperature cooling of 7.1 °C. This study offers a new approach to designing an energy-saving smart window system with multifunctionality.

Constructing a cellulose based chiral liquid crystal film with high flexibility, water resistance, and optical property.

Cellulose nanocrystal (CNC) derived from cellulose can form a liquid crystal film with bright structural color by evaporative-induced self-assembly (EISA). As a new class of photonic liquid crystals material, it has attracted much attention because of its intrinsic unique structural characteristics and excellent optical properties. However, the brittleness and water sensitivity of CNC film have hindered its practical application. Herein, multiple cross-linked networks CNC/(polyethylene glycol diacrylate:polyethylene oxide) (PEGDA:PEO) composite film was prepared through EISA and UV irradiation strategies. The as-prepared film exhibits high-flexibility with a fracture strain of up to 36.40 % and strong water resistance, with water absorption at an equilibrium of only 17.41 %. Moreover, the film retains its structural color in aqueous solution for a long time due to its water stability. The outstanding flexibility and water resistance of CNC composite film are attributed to multiple crosslinked networks (i.e. PEGDA, PEO, and PEDGA-PEO networks), which endow the film with excellent stress dispersion and transferability when stretched and limit film swelling in water without affecting chiral nematic structures of CNC. Overall, this work provides a promising strategy to prepare CNC-based film with high-flexibility, water resistance, and optical property for applications like decoration, sensor, and anti-counterfeiting.

Thermal- and pH-responsive triple-shape memory hydrogel based on a single reversible switch.

Here we provide a novel method for fabricating a pH- and thermal-responsive triple-shape memory hydrogel based on a single reversible switch phase. A high-density quadruple hydrogen-bonding ureido-pyrimidinone (UPy) system was introduced into the hydrogel network, which can occur to varied degrees of dissociation under different pH and temperature conditions. Different degrees of dissociation and reassociation can be viewed as different subsets of memory elements to freeze and unfreeze the temporary shapes. Although this class of hydrogels contains only a single transition phase, they feature a large dissociative differential in response to varied external stimuli to provide multiple windows for programming different temporary shapes.

Correction: One-step mild preparation of tough and thermo-reversible poly(vinyl alcohol) hydrogels induced by small molecules.

Correction for 'One-step mild preparation of tough and thermo-reversible poly(vinyl alcohol) hydrogels induced by small molecules' by Chuang Dong et al., Chem. Commun., 2021, 57, 3789-3792, https://doi.org/10.1039/D1CC00578B.

Disulfide Bond Accelerated Transesterification in Poly(ß-hydrazide disulfide esters) toward Fast Network Rearrangements.

The development of catalyst-free ester-based covalent adaptable networks (CANs) provides a new approach to achieve milder reaction conditions to reprocess thermoset resins. Despite recent advances, however, accelerating network rearrangements requires the introduction of hydroxyl groups into the network. In this study, disulfide bonds are introduced into the CANs to add new kinetically facile pathways to accelerate network rearrangement. Kinetic experiments using small molecule models of the CANs show that the presence of the disulfide bonds can accelerate transesterification. These insights are applied to synthesize new kinds of poly(ß-hydrazide disulfide esters) (PSHEs) using thioctic acyl hydrazine (TAH) as a precursor for ring-opening polymerization with the hydroxyl-free multifunctional acrylates. The PSHE CANs have lower relaxation times (505-652 s) than the polymer containing only ß-hydrazide esters (2903 s). The ring-opening polymerization of TAH improves the crosslinking density, heating resistance deformation temperature, and UV shielding performance of the PSHEs. Thus, this work provides a practical strategy to reduce the reprocessing temperatures of CANs.

Tunable Red Clusteroluminescence Polymers Prepared by a Simple Heating Process.

Clusteroluminescence (CL) has drawn much attention in recent years. However, the design of red emission clusteroluminogens (CLgens) with tunable CL is still in its infancy. Herein, we report a simple heating process to prepare red emission poly(maleic anhydride-alt-vinyl acetate) (PMV) derivatives with a tunable maximum emission wavelength between 620 and 675 nm. First, heating above the glass transition temperature (Tg) would promote the movement of polymer chains and facilitate the formation of clusters in both solid and solution states. Then, heating beyond the decomposition temperature at which vinyl acetate converts into C═C is favorable to the formation of new clusters and large through-space conjugation among subgroups in polymer chains. Their synergistic effects realize the adjustable emission wavelength and higher quantum yield of polymers. Additionally, low-cost and eco-friendly core-shell PMV particles are prepared as agricultural light conversion agents and exhibit great compatibility with polyethylene.

Preparation of high electromagnetic interference shielding and humidity responsivity composite film through modified Ti3C2Tx MXene cross-linking with sodium alginate.

This paper established a new kind of L-citrulline-modified MXene cross-linked sodium alginate composite film through solution blending and casting film methods. The L-citrulline-modified MXene cross-linked sodium alginate composite film exhibited high electromagnetic interference shielding efficiency of 70 dB and high tensile strength of 7.9 MPa, which were much higher than the sodium alginate film without L-citrulline-modified MXene. In addition, the L-citrulline-modified MXene cross-linked sodium alginate film appeared humidity responsibility in a water vapor environment, the weight, thickness, and current appeared to increase trend and the resistance appeared to decrease trend after it absorbed water, and these parameters recovered to their original values after drying.

Designing Strong, Tough, Fluorescent, and UV-Shielding PLA Materials by Incorporating a Phenolic Compound-Based Multifunctional Modifier.

The realization of high stiffness, high extensibility, and multi-functions for polylactic acid (PLA) is a vital issue for its practical applications. Herein, hydroxyalkylated tannin acid (mTA), a phenolic compound-based modifier with plentiful flat aromatic structures and flexible isopropanol oligomers, is designed and fabricated to act as the multifunctional modifier for PLA. The mTA exhibits the capability of emitting fluorescence and blocking UV light due to the combination of flat aromatic structures and plentiful flexible chains. Besides, mTA with high grafting degree (h-mTA) shows an excellent compatibility to PLA due to the hydrogen bonding interface and the high affinity of grafted isopropanol oligomers to PLA. As a result, the as-prepared PLA/h-mTA20 composite exhibits a strikingly improved extensibility by 61.2 times while maintaining the high yield strength of PLA. Moreover, PLA/h-mTA can serve as a fluorescent material with multi-mode responsiveness as well as a UV-shielding material with high transparency. We envision that this work opens a novel yet facile way to prepare a strong, tough, and multifunctional PLA material with expanded application scopes and will promote the practical applications of phenolic compounds in polymers.

High-Strength, Degradable and Recyclable Epoxy Resin Based on Imine Bonds for Its Carbon-Fiber-Reinforced Composites.

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.

Selective Immobilization of His-Tagged Enzyme on Ni-Chelated Ion Exchange Resin and Its Application in Protein Purification.

Ion exchange resins are suitable as carriers for immobilized enzymes because of their stable physicochemical properties, appropriate particle size and pore structure, and lower loss in continuous operation. In this paper, we report the application of the Ni-chelated ion exchange resin in the immobilization of His-tagged enzyme and protein purification. Acrylic weak acid cation exchange resin (D113H) was selected from four cationic macroporous resins that could chelate the transition metal ion Ni. The maximum adsorption capacity of Ni was ~198 mg/g. Phosphomannose isomerase (PMI) can be successfully immobilized on Ni-chelated D113H from crude enzyme solution through chelation of transition metal ions with the His-tag on the enzyme. The maximum amount of immobilized PMI on the resin was ~143 mg/g. Notably, the immobilized enzyme showed excellent reusability and maintained 92% of its initial activity with 10 cycles of catalytic reaction. In addition, PMI was successfully purified using an affinity chromatography column prepared by Ni-chelated D113H, which showed the potential for the immobilization and purification process to be realized in one step.