Quaternary Ammonium Salt-Based Intrinsic Antibacterial Polyurethanes: Optimizing the Antibacterial Activity via Cationic Main- or Side-Chain Design in Hard Segments

Synthesis and Characterization of New Hydrolytic Resistant Antibacterial Pyridinium and N-Alkyl Ammonium-Containing Methacrylamides for Dental Resin Adhesives

Resin-based composites have relatively short lifetime mainly attributed to hydrolytic and enzymatic degradation of easily hydrolyzed methacrylates in the dental resin adhesive. To address these problems, a series of antibacterial and hydrolytic resistant methacrylamide monomers containing quaternary ammonium salts and long alkyl chains, MAPs, MADAs, and BMADPB were synthesized. Synthesized methacrylamides exhibited antibacterial activities against S. mutans and E. faecalis. Factors that affect the antibacterial activities are intermolecular hydrogen bonding and alkyl chain length. Some synthesized methacrylamides expressed equal or lower cytotoxic activities against mouse dental papilla cell lines than those of bis-GMA and MDPB, common methacylates used in dental resin adhesives. Degree of conversion at 30 s, the clinically relevant exposure time for tooth restoration, of methacrylamides (51%-83%) were lower than that of the reference antibacterial methacrylate, MDPB (98%) due to lower reactivity of methacrylamide compared with methacrylate. Addition of selected methacrylamides in the resins remarkably improved flexural modulus after water storage. Hydrolysis experiment in acidic condition of the synthesized monomers and their corresponding polymers proved their hydrolytic stability. Antibacterial activities, cell viability, mechanical strength, and hydrolytic stability of new methacrylamides represent alternative antibacterial and durable monomers for resin adhesives.

Photo-responsive superhydrophobic cellulose aerogel films from spiropyran and fluorinated modified copolymer brushes through surface-initiated ring-opening metathesis polymerization

Surface functionalization of natural polymers with polymer brushes is an effective strategy for enhancing their structural and functional properties. Designing spiropyran-based responsive biopolymers is particularly significant for developing smart materials with tunable optical and electronic properties, enabling advanced applications in biointerfaces and biomedical technologies. In this study, we developed a surface-initiated ring-opening metathesis polymerization (SI-ROMP) approach to modify cellulose aerogel films, improving their hydrophobicity and photoresponsiveness. The cellulose aerogel films were fabricated via a water-based solution casting technique and subsequently functionalized with block copolymers of fluorinated polynorbornenes (pNBFn) and spiropyran-modified polynorbornenes (pNbSP). The polymer grafting efficiency reached 28.3 %, influenced by steric hindrance from the side chains. The modified films exhibited enhanced hydrophobicity, thermal stability, and dynamic photoresponsive behavior. Electrochemical impedance spectroscopy indicated that the incorporation of extended π-conjugated spiropyran moieties improved light absorption, charge transfer, and reversibility of optical and electrical properties. Furthermore, the films demonstrated stable and reversible photochromic behavior under visible light irradiation, with long-lasting wettability modulation. These findings highlight the potential of cellulose-based aerogels as multifunctional bio-compatible materials, offering promising applications in optical biosensors, bioimaging, anti-counterfeiting, and UV-responsive display technologies.

Highly sensitive and environmentally stable conductive eutectogels for flexible wearable sensors based on sodium alginate/poly(vinyl alcohol)/MXene

In recent years, flexible sensors have attracted much attention due to their wide range of applications. Eutectogel solved the problems of water loss and phase separation of conventional hydrogels. In this work, a purely natural polymer, sodium alginate (SA), was used to construct the network structure of the gel with MXene, PVA and deep eutectic solvent (DES) were used to initiate the physical cross-linking, and an antimicrobial eutectogel was synthesised by one-pot method, which possessed excellent mechanical properties (fracture strain of about 1350 % and fracture toughness of about 2.50 MJ/m3) and a high gauge factor (GF = 7.66). In addition, the resulting gels had good environmental stability (-20 °C-60 °C, maintained a highly repeatable response signal) and enabled wireless sensing. The sensor was capable of sensitively monitoring human joint movements and micro-expressions, which offered a wide range of application prospects for the development of wearable electronic products suitable for human movement.