Abstract Incorporating porous nanofillers into polymeric membranes has emerged as an effective strategy for overcoming the permeability–selectivity trade-off in CO2 separation. Carboxyl-functionalized polymer dots (Pdots) derived from a polymer of intrinsic microporosity (PIM-1) were developed and incorporated into a Pebax matrix to fabricate mixed-matrix membranes (MMMs) for CO2/N2 separation. The porous PIM-1-derived framework provided additional pathways for gas transport, whereas the carboxylic acid functionalities introduced by poly(styrene-co-maleic anhydride) (PSMA) enhanced the CO2 affinity and polymer–filler compatibility. As a result, Pdot incorporation simultaneously improved the CO2 permeability and CO2/N2 selectivity compared with those of pristine Pebax membranes. Among the prepared membranes, the MMM containing 0.5 wt % Pdot exhibited the best separation performance, achieving a CO2 permeability of 232.61 Barrer and a CO2/N2 selectivity of 53.47, compared with 148.99 Barrer and 40.27, respectively, for pristine Pebax. Consequently, the membrane performance approached the 2008 Robeson upper bound for the CO2/N2 separation. These findings demonstrate an effective strategy for engineering polymer-compatible porous nanofillers to regulate the membrane microstructure and gas transport in mixed-matrix membranes for CO2/N2 separation.
Abstract Although biological glue showed considerable potential for assisting patches in sealing tissue defects, its limited wet adhesion resulted in unreliable sealing or even detachment. Herein, we developed a wet adhesive Fe@LA glue by heating a mixed solution of ethyl lactate containing α-lipoic acid (LA) with ferric ion (Fe3+) to assist tissue patches in sealing defects. After being applied to the patch surface, the Fe@LA glue gradually cured upon contact with water. The strong hydrophobicity of the cured glue disrupted the hydration layer, allowing the carboxyl groups in its network to form interfacial bonds with tissues, which enabled the ReDura membrane (RM) patch to firmly adhere to wet bovine pericardium and achieve an adhesive strength of 54.3 kPa while withstanding a burst pressure of 37.0 kPa. Biosafety evaluations (cytotoxicity, hemolysis, acute systemic toxicity, subacute systemic toxicity, subcutaneous implantation, and skin irritation) confirmed its biocompatibility when the coating amount was ≤2 mg/cm2. In both porcine gastric defect sealing and rat liver hemostasis models, the patches with Fe@LA glue showed effective sealing and hemostasis, highlighting its promise for suture-free sealing of tissue defects.
Abstract Photosensitive thermosets are used extensively in applications such as coatings and 3D printing because of their simple processing and superior properties emerging from their cross-linked molecular network structure. Limitations of thermosets are associated with their intrinsic brittleness and lack of reprocessability. While brittleness can be mitigated by tuning the chemical composition and introducing heterogeneity, the lack of reprocessability can only be addressed by incorporating dynamic covalent bonds into their structures. Such bonds may undergo dynamic bond exchange above the topology freezing temperature, Tv, which provides self-healing, reprocessability, and recyclability to these materials. While various bond exchange mechanisms have been explored so far, to our knowledge, UV-curable acrylate-based covalently adaptable networks (CANs) undergoing bond exchanges via urethane linkage chemistry have not been discussed in the literature. In this study, we develop photosensitive CANs which activate self-healing through both associative transcarbamoylation and dissociative urethane exchange. Associative transcarbamoylation requires the presence of OH groups and a Brønsted acid catalyst, while the urethane exchange mechanism could be triggered in the absence of catalyst and hydroxyl groups. For the compositions investigated, strength ranges from 7 to 66 MPa, Young’s modulus ranges from 80 MPa to 2.3 GPa with failure strains between 30% and 7%, and toughness in the range 1 to 3.24 MJ/m3, while Tg ranges from 21 to 87 °C. Cross-link density governs the mechanical behavior and the stress relaxation kinetics associated with dynamic bond exchange, with slower relaxation rate and improved mechanical properties as the cross-link density increases. This study extends the scope of photosensitive acrylates to urethane-based CANs with tunable mechanical properties.
Abstract Natural materials with hierarchical architectures, such as spider silk, integrate strength, toughness, and environmental adaptability within a single framework. Inspired by this multifunctionality, we report a waterborne polyacrylate emulsion platform for constructing recyclable covalent adaptable networks (CANs) through dual dynamic covalent cross-linking. Methyl methacrylate (MMA) and butyl acrylate (BA) serve as hard and soft segments, while acetoacetoxyethyl methacrylate (AAEM) provides reactive sites for network formation. The network incorporates Schiff-base linkages and disulfide bonds and exhibits thermally activated stress relaxation and hot-press reprocessability. By tuning the MMA/BA ratio and AAEM content, the network structure and mechanical properties are programmable. The optimized SS-POM6.5B3.5-3 film exhibits a Young’s modulus of 116 MPa, an elongation at break of 365%, and a gel content of ≈94%. It also functions as an adhesive and a reprocessable matrix for conductive carbon nanotube (CNT) composites. This bioinspired waterborne acrylic platform integrates tunable mechanics, substrate-dependent adhesion, thermal reprocessability, and conductive functionality for multifunctional adhesive applications.
Abstract To address the issue of lignin agglomeration in poly(ethylene adipate-co-terephthalate) (PEAT) matrix, which leads to degraded composite performance, this study employed vinyltrimethoxysilane (VTMS) to modify lignin, producing VTMS-grafted lignin (VL). Subsequently, VL was blended with PEAT at different proportions to fabricate PEAT/VL composites. The mechanical properties, micromorphology, thermal behavior, water absorption, and UV-shielding performance of the resulting composite films were systematically evaluated to determine the effect of VL content on the properties of PEAT/VL composites. The results indicate that VTMS graft modification significantly improved the dispersion of lignin in the PEAT matrix and enhanced the interfacial compatibility between the two phases. SEM and contact angle measurements confirmed that through simple silane modification, the contact angle of lignin increased from 53.1° to 130.2°, significantly enhancing its hydrophobicity and effectively suppressing the agglomeration of lignin particles in the PEAT matrix. Compared with the unmodified lignin (AL) system, the tensile strength of the PEAT/VL-5% composite increased from 23.4 to 28.9 MPa (a 23.5% increase), and the elongation at break increased from 990% to 1172% (an 18.4% increase). When the VL content was 10%, the tensile strength and elongation at break of the PEAT/VL composite were comparable to those of pure PEAT and could still meet the practical application requirements for films. At the same time, the PEAT/VL composites exhibit highly efficient full-spectrum UV shielding performance in the 280 nm-400 nm UV range. Furthermore, after 144 h of UV aging, the tensile strength retention and elongation at break retention of the PEAT/VL-5% and PEAT/VL-10% composites exceeded 57% and 88%, respectively, effectively delaying the photodegradation of PEAT. This study provides a valuable reference for the development of PEAT-based biodegradable composites with both excellent mechanical properties and UV-shielding capabilities, laying the foundation for their large-scale application in environmentally friendly fields such as packaging and agricultural mulch films.
