The N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) solvent system is one of the most effective solvents for polybenzimidazole (PBI). Despite its widespread industrial application in PBI processing, the dissolution mechanism at the molecular level remains poorly understood. In this work, the model compound PhBI was employed to investigate the interactions within the PBI/DMAc/LiCl solution via Fourier-transform infrared (FTIR) spectroscopy and multinuclear NMR spectroscopy (1H, 7Li, 13C, and 35Cl). The results demonstrate that upon dissolution of PBI in the DMAc/LiCl system, Cl− ions insert into the PBI chains and establish NH⋯Cl− hydrogen bonds with the imino protons. This interaction disrupts the original hydrogen-bonding network of PBI while simultaneously inducing the dissociation of tightly bound Li+-Cl− ion pairs. To maintain charge balance, Li+ ions, together with coordinated DMAc molecules, are attracted along the PBI chains, leading to the dispersion of the PBI chains and the formation of a homogeneous solution. Through a model analogy approach, this work elucidates the intermolecular interactions governing PBI dissolution in DMAc/LiCl and infers the underlying dissolution mechanism. These findings provide critical insights for understanding and optimizing PBI dissolution conditions, enhancing industrial processing techniques, and designing novel solvent systems for PBI.
Composite current collectors (CCCs) are promising for improving the mass energy density and safety characteristics of lithium-ion batteries (LIBs), but are recently challenged by poor combination between polymer matrix and metal layer. In this study, a poly(ethylene terephthalate) (PET) based composite current collector (PET-DMDSbasic-Al) was fabricated by constructing a silane coupling agent (KH-560)/ dimethoxydimethylsilane (DMDS) co-hydrolyzed polysiloxane interlayer on the surface of PET, followed by magnetron sputtering of an aluminum (Al) layer, where linear molecular chain formed in the polysiloxane interlayer under alkaline condition. It demonstrates that the linear polysiloxane chain contributes to the formation of refined Al crystals, further enables PET-DMDSbasic-Al a modulus approximately 300 MPa higher than that of PET-Al current collectors, together with a 3.8-fold increase in elongation at break. In addition, the Al shedding area was reduced from 10.03% for PET-Al to 2.11% for PET-DMDSbasic-Al. Owing to the strong adhesion of Al layer on PET brought by linear polysiloxane and Al crystal grains controlled by growth conditions, the modified collectors also show significant improvements in corrosion resistance, thermal stability, and electrochemical performance compared to representative reported works. This study provides an effective interfacial engineering strategy and a practical materials basis to develop PET-based composite current collectors for LIBs safety.
The development of functional, biodegradable polyesters is critical for addressing the environmental persistence of conventional plastics. Coumarin-functionalized polyesters were synthesized through zinc-catalyzed ring-opening copolymerization (ROCOP) of succinic anhydride (SA), a coumarin-containing epoxide (ECM), and phenyl glycidyl ether (PGE). To the best of our knowledge, this is the first example of a coumarin-functionalized glycidyl ether monomer incorporated into an epoxide/anhydride ROCOP system. Structural characterization by NMR spectroscopy, GPC, and mass spectrometry confirmed the formation of alternating polyester architectures and successful incorporation of coumarin functionalities. By varying the ECM/PGE ratio, polymers with tunable molecular weights (4.5–32 kDa) and glass-transition temperatures (32–49 °C) were obtained. Upon UVA irradiation (365 nm), pendant coumarin groups underwent efficient [2 + 2] photodimerization, achieving degrees of dimerization up to 86% and gel fractions up to 80.5%. Photo-crosslinking significantly enhanced the thermal properties of the polymers, resulting in glass-transition temperature increases of up to +34 °C. The alternating copolymer P(SA-alt-ECM) exhibited the largest response, with Tg increasing from 48 to 82 °C following irradiation. These results demonstrate that coumarin photochemistry can be effectively integrated into ROCOP-derived polyesters, providing a versatile platform for the design of photoresponsive polymer networks with tunable crosslink density and thermomechanical properties.
This research focused on the development and characterization of novel composite materials based on commercial LDPE/EVA, aiming to improve their flame-retardant (FR) and photodegradability properties. To achieve this, styrene-acrylonitrile (SAN) and styrene-vinyltetrazole (StVTz) copolymers were synthesized and characterized. These copolymers were selected due to their potential to enhance FR performance, combined with the incorporation of TiO2 to promote photodegradation and, consequently, the biodegradability of the composites. Six LDPE/EVA-based formulations incorporating StVTz, ammonium polyphosphate (APP), and TiO2 were prepared. Processing was carried out using a Brabender Intelli-Plasticorder for melt mixing, thermoforming presses for plate production, and Xplore extrusion equipment for film fabrication. FTIR and NMR spectroscopy were used to characterize the chemical structures of the synthesized copolymers. At the same time, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to evaluate their thermal properties. The flame-retardant performance of the composites was investigated using cone calorimetry and UL-94 tests. Colorimetric analysis was conducted to evaluate changes in yellowing after UVA-340 irradiation in an accelerated aging chamber at different exposure times (200, 400, and 600 h). FTIR analysis was also used to identify changes in functional groups associated with oxidative degradation processes. In addition, the antimicrobial activity of the composites was assessed using the zone-of-inhibition method. Cone calorimetry results demonstrated a significant improvement in FR performance, attributed to the formation of a protective char layer. Sample F exhibited a 59.4% reduction in peak heat release rate (pHRR), an increase in time to ignition (TTI) to 160 s compared to 113 s for the LDPE/EVA blend, and a reduction in FIGRA from 13.30 to 6.13 kW/m2·s. This composition achieved a UL-94 HB rating. Overall, the evaluated LDPE/EVA-based composites are promising materials for flame-retardant applications. Furthermore, the results indicate favorable photodegradation behavior, providing evidence of their potential biodegradability.
The rapid advancement of wearable and portable medical electronic devices demands flexible electromagnetic interference (EMI) shielding materials with excellent mechanical properties and high shielding effectiveness. Herein, we report an anisotropic MXene/polyvinyl alcohol (PVA)/cellulose nanofibers (CNF) (MPC) hydrogel fabricated via a simple physical cross-linking strategy combined with directional freezing technique. At an MXene loading of 4.0 wt%, the resulting MPC hydrogel achieves a tunable average EMI shielding effectiveness (SE) ranging from approximately 33 to 65 dB over a thickness of 2–10 mm. In addition, the hydrogel exhibits excellent UV shielding performance and reliable sensing stability. Interestingly, the macrostructural morphology of the MPC hydrogel resembles a “pine-tree-like” architecture, which imparts anisotropic EMI shielding properties, with the axial direction showing slightly higher shielding effectiveness than the radial direction. Furthermore, the bidirectionally freeze-cast MPC hydrogel demonstrates notably improved compressive strength, attributed to the formation of abundant physical cross-linking points between MXene and the polymer matrix, leading to a denser network structure. This study provides a new strategy for developing flexible sensors based on hydrogels featuring low filler loading and bidirectional electromagnetic shielding performance.
In industrial water systems, calcium salt scaling and corrosion-product deposition reduce heat-transfer efficiency, decrease membrane flux, and increase operational energy consumption, highlighting the need for efficient, phosphorus-free, and environmentally benign scale inhibitors. In this study, pullulan-grafted polyacrylic acid (PU-PAA) with different grafting degrees was synthesized via aqueous free-radical graft copolymerization using natural pullulan polysaccharide (PU) as a green macromolecular backbone, thereby integrating polysaccharide-derived steric hindrance with carboxyl-mediated coordination. Static inhibition tests showed that, under optimized conditions, PU-PAA achieved inhibition efficiencies of over 90% for Ca₃(PO₄)₂ at 30 mg/L and 87.2% for CaSO₄ at 10 mg/L, outperforming commercial PAA and PASP. PU-PAA also exhibited good dispersion stability toward iron oxide particles, indicating its potential for multifunctional water treatment. Its inhibition performance, long-term stability, and environmental compatibility under different water-quality conditions were further evaluated. Crystal-structure characterization and molecular dynamics simulations revealed that PU-PAA disrupts calcium scale crystallization through the synergistic effects of carboxyl-group density, adsorption on active crystal sites, and steric hindrance from the polysaccharide backbone, clarifying the relationship among carboxyl-group density, crystal-growth inhibition, and macroscopic scale-inhibition performance. This work provides a basis for designing green composite scale inhibitors based on pullulan polysaccharides and synthetic polycarboxylic acids.
Combating bacterial multispecies biofilms is a challenge that can be addressed by disrupting cell-to-cell communication through the targeting of structurally diverse signaling molecules. This work focuses on the use of molecularly imprinted polymers (MIPs) to limit biofilm formation via controlling the quorum sensing (QS) regulated by autoinducers such as N-acyl homoserine lactones (AHL). For that purpose, a short-chain AHL (C2-AHL) was used as dummy template with the aim of elaborating versatile MIPs capable to sequester a wide range of AHL-based autoinducers. MIPs composition was rationally designed using NMR studies for the functional monomer selection. Two acrylamide-based MIPs were synthesized via precipitation polymerization at different temperatures (70 and 80 °C). They were characterized by FTIR, SEM and nitrogen adsorption/desorption experiments. The MIPs showed adsorption capacities up to 29.1 μmol/g and imprinting factors up to 2.4 toward C2-AHL. Their biological activity was assessed on two bacterial strains, Vibrio harveyi (BB475) and Pseudomonas putida (F117) which respond to 3-OH-C4-AHL and 3-oxo-C12-AHL autoinducers, respectively. Rebinding studies showed that MIPs displayed similar specificity toward these two AHLs as for the dummy template used. Employing biological assays, MIPs demonstrated effective QS control through AHL adsorption, as evidenced by a reduction of 97% in relative bacterial luminescence and 50% attenuation of P. putida biofilm formation, at the same level as the negative control without AHL. Altogether, this indicated a high efficiency of MIPs in reducing AHL concentrations. The developed MIPs represent a promising quorum-sensing attenuation strategy toward the control of AHL-mediated biofilm formation across different bacterial species.
Osteoporosis (OP) is a systemic metabolic bone disease characterized by reduced bone mass, deteriorated bone tissue microstructure, and increased bone fragility, which has become a major global public health challenge amid population aging. Current clinical anti-osteoporosis drugs are mainly limited by single mechanism of action, poor bone targeting, and severe systemic side effects. Simvastatin (Sim) exerts dual regulatory effects on bone metabolism by promoting osteogenesis and inhibiting osteoclastogenesis, showing great potential for OP treatment. However, its clinical translation is severely hindered by hydrophobicity, low bioavailability, lack of bone targeting, and high risk of off-target toxicity. In this study, we constructed a multifunctional nanocomposite (designated as AHPS) using alendronate (ALN) as the bone-targeting moiety, hyaluronic acid (HA) as the functional matrix, polyethylenimine-polylactic acid (PEI-PLA) as the drug-loading core, and Sim as the therapeutic agent. The physicochemical properties, drug loading and release behavior, bone-targeting ability, and biosafety of AHPS were systematically characterized. In vitro experiments demonstrated that AHPS synergistically promoted mineral deposition, upregulated the expression of osteogenic-related genes, and enhanced osteoblast differentiation and mineralization via the combined effects of HA and Sim. In vivo experiments in ovariectomized (OVX) mice revealed that AHPS specifically accumulated in bone tissue, significantly restored bone mineral density and trabecular microstructure, and upregulated the expression of key osteogenic markers. This bone-targeted nanocomposite achieves multi-dimensional regulation of the osteogenic microenvironment and provides a novel, safe, and efficient strategy for the treatment of postmenopausal osteoporosis with excellent clinical translation potential.
The present review provides a comprehensive and integrated overview of chitosan derivative-based hydrogels, emphasizing how specific chemical modifications influence hydrogel functionality and application potential. Chitosan, a naturally derived polysaccharide obtained from chitin, possesses excellent biocompatibility, biodegradability, antimicrobial activity, and structural similarity to the extracellular matrix; however, its poor solubility and limited mechanical stability under physiological conditions restrict wider applications. To address these limitations, this review systematically discusses major derivatization strategies, including carboxymethylation, quaternization, thiolation, hydroxyalkylation, sulfonation, phosphorylation, and graft copolymerization, highlighting their effects on solubility, swelling behavior, mechanical strength, stimuli responsiveness, and biological performance.This article critically correlates derivatization techniques with crosslinking approaches, hydrogel architecture, and resultant functional properties, providing a clearer framework for rational hydrogel design. Particular emphasis is placed on recent advances in multifunctional and stimuli-responsive hydrogels for wound healing, drug and gene delivery, tissue engineering, antimicrobial therapy, and injectable regenerative systems. In addition, emerging non-biomedical applications, including environmental remediation, water purification, biosensing, agriculture, food preservation, and cosmetic formulations, are comparatively discussed to demonstrate the expanding translational scope of chitosan derivatives. The review also identifies challenges and future perspectives focusing on green synthesis, hybrid multifunctional systems, and clinically translatable hydrogel platforms. Overall, this review offers a distinct structure–property–application perspective that may guide the next generation design of sustainable and high-performance chitosan-derived hydrogels for biomedical and environmental technologies.
Polymers have long contributed to energy reduction through lightweight design, yet reinforcement strategies often rely on inorganic fillers that increase density and compromise interfacial compatibility. Extending the intrinsic advantages of polymers therefore requires organic reinforcing phases that preserve low density while providing effective load transfer. Aromatic polyamide whiskers, formed via reaction-induced crystallization, offer a promising solution owing to their high crystallinity, anisotropic morphology, and organic composition.Here, we report bio-derived poly(p-benzamide) (PBA) whiskers synthesized from microbially produced p-aminobenzoic acid (pABA) and directly compare them with whiskers prepared from petroleum-derived monomers under identical processing conditions. The results show that the differences between the two systems are generally subtle and may arise from differences in synthetic routes, although slight variations in crystallization behavior, surface morphology, and thermal decomposition were observed under identical conditions.Quantitative analysis indicates that these differences are not uniform across all crystallographic directions or properties.These observations suggest that multiple factors may influence crystallization behavior, although the exact origin cannot be unambiguously determined within the scope of this study.
Cancer remains a leading cause of global mortality, yet conventional chemotherapy is limited by systemic toxicity, nonspecific biodistribution, and multidrug resistance. To address these challenges, we developed dual-functional nanocarriers based on non-isocyanate polyurethanes (NIPUs) synthesized via an eco-friendly route under mild conditions. The amphiphilic NIPU backbone integrates two key motifs: folic acid (FA) for active targeting of folate receptor-overexpressing cells, and cystamine-derived disulfide bonds for glutathione (GSH)-responsive degradation. The final polymers self-assembled into stable nanocarriers (∼160 nm) with high doxorubicin (DOX) loading capacity (∼ 24%) and encapsulation efficiency (∼ 94%). The nanocarriers exhibited pronounced redox sensitivity, releasing 80% of DOX within 48 h under tumor-mimetic GSH conditions (10 mM), versus <30% release at physiological GSH levels (10 μM). Dynamic light scattering and SEM analyses confirmed GSH-triggered disulfide cleavage, leading to nanocarrier destabilization and aggregation that synchronizes drug release with cellular internalization. In vitro studies demonstrated superior cytotoxicity and cellular uptake in folate receptor-positive MDA-MB-231 cells compared to receptor-low MCF-7 cells, with FA/redox dual-functionalized NIPU/DOX nanocarriers significantly outperforming non-targeted controls. This enhanced therapeutic precision arises from the synergistic integration of passive targeting (EPR effect), active FA-mediated recognition, and tumor-specific redox activation—enabling selective drug delivery while minimizing off-target effects. Our in vitro findings establish a sustainable platform for stimuli-responsive nanomedicine that overcomes key limitations of conventional chemotherapy through green polymer chemistry.
Osteochondral tissue exhibits a complex zonal architecture and poor intrinsic healing capacity, yet the development of in vitro models that approximate its structural and interfacial features remains challenging. In this study, we report a continuous multizonal poly(ε-caprolactone) based scaffold incorporating a nanofibrous tidemark to represent the superficial, middle, deep, calcified cartilage, and subchondral bone zones of native osteochondral tissue. Three scaffold designs with distinct fibre and pore architectures were fabricated by combining solution blow spinning, melt-electrospinning, and solution electrospinning. Morphological characterization showed morphological continuity with no visible interlayer separation, high porosity (86.1–89.9%), and interconnected pore structure throughout the scaffolds. Incorporation of hydroxyapatite into the mineralized layers was evaluated by FT-IR, EDS and ICP-OES analyses. Non-thermal plasma modification improved scaffold wettability from 108 ± 1.7° to a cell adhesive range of approximately 51.3 ± 1.8°, while swelling and degradation studies demonstrated structural stability with minimal weight loss over 21 days under physiological in vitro conditions. Mechanical testing showed compressive recovery of 84–92%, apparent tensile strengths of 1.74–2.09 MPa, and elongation at break ranging from 101.6% to 185.2% across the scaffold designs. Spatial separation of the two differently labelled C28/I2 cell populations seeded from opposite scaffold compartments was maintained after 10 days of culture, supporting the barrier function of the tidemark. These results demonstrate that the developed scaffold provides a stable and compartmentalized platform for osteochondral in vitro studies and potential osteoarthritis related applications.
To enable the recycling of carbon fiber composites, this study developed a resveratrol-based epoxy vitrimer containing double dynamic covalent bonds (ester and disulfide bonds) by using bio-based polyphenolic resveratrol epoxy resin (RE), with dynamic disulfide-containing lipoic acid (LA) as a crosslinking agent and curing agent phthalic anhydride (PA). By adjusting the ratio of the crosslinking agent to the curing agent, the synergistic optimization of the thermal and mechanical properties of the epoxy vitrimer and its composite was achieved. A variety of testing methods were employed to systematically investigate the thermal properties, mechanical properties, and chemical degradation behavior of this epoxy vitrimer. Carbon fiber reinforced composites (CFRCs) based on this epoxy vitrimer were subsequently fabricated. The CFRC reached its optimal mechanical and recycled properties when the resin system had a molar ratio of RE (epoxy): LA (carboxyl): PA (carboxyl) = 5: 1: 4 and the composite resin content was 40% ± 2.7%. Finally, the composite was immersed in a mixed solution of DMF and β-mercaptoethanol (2-ME) (1: 1, v/v), which successfully dissolved the matrix resin and obtained relatively pure carbon fiber.
To meet the demand for sustainable additive manufacturing, this study addresses the bottlenecks of conventional bio-based photosensitive resins, including high viscosity, poor printability, weak mechanical properties, and non-degradability. Using bio-based castor oil (CO) and degradable polycaprolactone (PCL) as dual matrices, we synthesized a polyurethane acrylate (PUA) photosensitive resin containing hindered urea bonds (HUBs) dynamic covalent networks. High-strength-toughness, biocompatible, and biodegradable elastomers were fabricated via digital light processing (DLP) 3D printing and photo-thermal dual curing. A systematic comparison of three diisocyanates (HMDI, HDI, IPDI) revealed that IPDI-PUA exhibited the optimal comprehensive performance after heat treatment at 100 °C: tensile strength of 21.47 ± 0.85 MPa, elongation at break of 811.35 ± 0.21%, toughness of 96.60 ± 1.27 MJ/m3, and excellent thermal stability. The materials were non-cytotoxic, complying with ISO 10993-5; they degraded completely in alkaline conditions within 24 days and gradually disintegrated in soil after 150 days, while remaining structurally stable in the oral physiological environment. This system was successfully applied to DLP 3D printing of transparent orthodontic aligners, providing a new strategy for green degradable bio-based 3D printing materials in personalized medical devices.
In this study, based on a molecular structure design strategy, acrylate-modified hydroxyl-terminated tetrahydrofuran-ethylene glycol copolyether (PUA) was successfully synthesized via the reaction of hydroxyl-terminated tetrahydrofuran-ethylene glycol copolyether (HTPE), dicyclohexylmethane diisocyanate (HMDI), and hydroxyethyl acrylate (HEA) as starting materials. FTIR, 1H NMR, and GPC characterizations confirmed that the as-synthesized PUAs featured an acrylate-terminated structure, with a weight-average molecular weight (Mw) of 20,000 g/mol. The low-molecular-weight, moderately viscous PUA-3 was formulated with the reactive diluent HEA and photoinitiator 1173. By tuning the content of the reactive diluent, a series of HTPE-based photocurable binders (designated as the P-HEA series) were prepared. The optimal formulation consisted of 30 wt% HEA, yielding cured specimens with a tensile strength of 4.12 MPa and an elongation at break of 196.2%. Building upon the above findings, the low-viscosity P-HEA1 binder was blended with calcium carbonate, aluminum powder, and a composite formulation to prepare photocurable slurries. The results demonstrated that the photocurable slurry exhibited favorable rheological behavior and sedimentation stability, while the printed specimens possessed excellent mechanical properties. Specifically, the composite-formulation specimen achieved a mechanical strength of 1.02 MPa and an elongation at break of 63.6%. Furthermore, a high-precision star-perforated grain with a 50 wt% solid content was successfully fabricated via a DLP-based photocuring 3D printer. These findings provide experimental evidence and technical support for the application of HTPE-based photocurable binders in 3D-printed composite materials.
Porous polymer films with controllable surface wettability and pore architecture are promising materials for oil uptake and solvent recovery. Herein, UV-cured fluorinated porous polyurethane (FPU) films were prepared by casting high internal phase emulsion (HIPE) precursors onto polytetrafluoroethylene templates, followed by UV-induced thiol-ene click polymerization. The effects of Span-80/B246 blended surfactants on HIPE stability, pore formation, surface wettability, and uptake behavior were systematically investigated. By adjusting the Span-80:B246 ratio and total surfactant content, the emulsion stability and porous film structure were effectively regulated. Stable HIPEs were obtained at Span-80:B246 ratios of 2:1–4:1, while increasing Span-80 content generally produced smaller pores and a more compact architecture. FTIR and XPS confirmed the incorporation of fluorinated moieties into the polyurethane network. The apparent water contact angle reached 102.09o at a Span-80:B246 ratio of 1:1 and 25 wt% surfactant loading, owing to the combined effects of fluorinated surface chemistry and porous morphology. The optimized FPU films showed enhanced oil and organic solvent uptake, especially for dichloromethane, mainly due to regulated pore connectivity, capillary filling, and polymer-solvent affinity. This work provides a useful approach for designing UV-cured porous fluorinated films for oil uptake and solvent recovery.
In this study, two kinds of furan-terminated small molecules (FS and FC) were synthesized via amidation reactions between furfurylamine and polyacids (sebacic acid or citric acid), respectively, and were incorporated into the furan-functionalized epoxidized soybean oil (FE)/furan-terminated lignin (FL) thermo-reversible polymer network via Diels-Alder (DA) reaction to regulate the crosslinking density of the network. With the incorporation of DOPO-based reactive flame retardants (DE and DF), a structural optimized thermo-reversible/flame-retardant polymer with a reinforced network was fabricated. By introducing linear two-arm (FS) or branched three-arm (FC) structures, especially FC, the crosslinking density of the networks was significantly improved. As a result, the tensile strength, fracture toughness (KIC), and self-healing properties of the polymer were synchronously improved. The increased crosslinking density also enhanced the synergistic effect between FS/FC, lignin, and flame retardants, leading to improved char-forming ability and flame-retardant efficiency. The limiting oxygen index of 75FE/5FL/10FC/5DE/5DF reached 28.9% with the addition of only 5 wt% FL, enabling it to pass the UL-94 V-0 flammability rating. Compared with 100FE, this formulation exhibited reductions in total smoke production (TSP), smoke production rate (SPR), total heat release (THR), and peak heat release rate (pHRR) by 31.4%, 44.4%, 18.06%, and 21.67%, respectively. Additionally, it achieved a self-healing efficiency of 85.20% and retained 71% of its tensile strength after three reprocessing cycles. Through the aforementioned strategy, this work successfully overcomes the common trade-off among mechanical properties, self-healing efficiency, and flame retardancy in biobased dynamic polymers. It offers a practical example for developing sustainable, intelligent advanced polymeric materials for future applications.
Nonaromatic room-temperature phosphorescent (RTP) hydrogels are attracting increasing attention owing to their unique photophysical properties, environmental responsiveness, facile fabrication, and good biocompatibility, offering broad potential in bioimaging, information encryption, and flexible devices. Herein, we report a nonaromatic RTP hydrogel based on the synergistic effect of hydrophobic interactions and hydrogen bonding. A hydrogel is first prepared from partially hydrolyzed polyacrylonitrile previously reported by our group, and then it is acidified to convert carboxylate groups into carboxyl groups, leading to the formation of strong hydrogen bonding between the hydrophilic groups and the enhancement of hydrophobic interactions among cyano groups in the hydrogel. The synergistic effect of hydrogen bonding and hydrophobic interactions leads to dramatically enhanced mechanical and photoluminescent performances of the hydrogel. The obtained hydrogel exhibits a phosphorescence lifetime of 130.6 ms, an elastic modulus and maximum tensile stress of 43.8 and 7.4 MPa, respectively, and a shape memory effect. In addition, glycerol, oxalic acid, or polymaleic acid is introduced into the hydrogel to modulate hydrogen-bonding interactions, and the hydrogel with polymaleic acid exhibits a phosphorescence lifetime up to 151.0 ms, and enhanced elastic modulus and maximum tensile stress up to 105.3 and 7.6 MPa, respectively. Besides, the acidification of the hydrogel can be reversed by Na2CO3 treatment, which allows for information encryption by writing on the surface of the acidified hydrogel with a Na2CO3 solution. This study provides a new approach for constructing nonaromatic RTP hydrogels through synergistic noncovalent interactions.
Encapsulating a phase change material (PCM) within a robust shell represents a promising strategy to address the challenges such as volumetric change, leakage, flow, and contamination during reversible phase change processes in practical applications. To achieve this, casein-stabilized Pickering emulsions were subjected to UV irradiation to fabricate PCM-encapsulated microcapsules. First, native casein, without any pre-treatment, was directly employed to stabilize an oil phase of glycidyl methacrylate monomer in water. The emulsification efficiency of casein was investigated in detail. It has been discovered that stable Pickering emulsions with internal oil phase fractions ranging from 35 to 65 vol% can be obtained using 2.5 wt% casein, enabling high yield of poly(glycidyl methacrylate) (PGMA) microspheres with tunable sizes after photopolymerization within 3 min. Subsequently, cyclohexane, a monomer-compatible but PGMA-insoluble diluent, was mixed into the monomer phase to investigate alkane encapsulation within PGMA microspheres. Based on these findings, the PCM n-eicosane (C20) was encapsulated to produce PCM@PGMA microcapsules. The results indicate that up to 50 vol% of C20 can be incorporated into the oil phase of the Pickering emulsion, achieving an encapsulation efficiency exceeding 90%. Furthermore, the microcapsules demonstrate excellent robustness in terms of dimensional, thermal, and cyclic stabilities, highlighting their potential for applications such as thermal energy storage and temperature regulation. Hence, this work provides a rapid and facile strategy for fabrication of robust PCM microcapsules via photopolymerization of Pickering emulsions, where native casein can be directly used as a safe, green, low-cost and effective stabilizer.
