A facile preparation of a novel non-leaching antimicrobial waterborne polyurethane leather coating functionalized by quaternary phosphonium salt

Abstract The aim of this research is to develop a novel non-leaching antimicrobial waterborne polyurethane (WPU) leather coating material with covalently attached quaternary phosphonium salt (QPS). The structure of the QPS-bearing WPU has been identified, and their thermal stability, mechanical property, and antimicrobial performance have been investigated. The results reveal that the incorporation of QPS slightly reduces the thermal stability of WPU material but would not affects its usability as leather coating. Despite the presence of hydrophobic benzene in QPS structure, the strong hydration of its cationic groups leads to the increased surface contact angle (SCA) and water absorption rate (WAR) of the films, suggesting that the water resistance of the films needs to be improved for the purpose of leather coatings. Antibacterial tests demonstrate that when the QPS content is 20 wt%, QPS-bearing WPU shows effective antimicrobial activity against bacteria. The WPU containing QPS prepared in this study is a non-leaching antimicrobial material and has great potential application as leather coating. Graphical abstrac

Heteroaggregation in Binary Mixtures of Oppositely Charged Colloidal Particles

Heteroaggregation (or heterocoagulation) rate constants have been measured in mixtures of well-characterized colloidal particles of opposite charge with multiangle static and dynamic light scattering. This technique permits routine measurements of absolute heteroaggregation rate constants, also in the presence of homoaggregation. Particularly with multiangle dynamic light scattering, one is able to estimate absolute heteroaggregation rate constants accurately in the fast aggregation regime for the first time. Heteroaggregation rate constants have also been measured over a wide range of parameters, for example, ionic strength and different surface charge densities. Amidine latex particles, sulfate latex particles, and silica particles have been used for these experiments, and they were well characterized with respect to their charging and homoaggregation behavior. It was shown that heteroaggregation rate constants of oppositely charged particles increase slowly with decreasing ionic strength, and provided the surface charge is sufficiently large, the rate constant is largely independent of the surface charge. These trends can be well described with DLVO theory without adjustable parameters

Gelatin-Based Active Edible Film with pH-Sensing for Maintaining and Monitoring Fish Freshness

The development of packaging films with food preservation and monitoring functions is of great significance and applications. Herein, gelatin was combined with rosmarinic acid (RosA) and blueberry anthocyanin extract (BAE) to fabricate RosA-gelatin/BAE (RGA) films with pH-responsiveness and long-term antioxidant and antibacterial activities. The films have better surface hydrophobicity and antiswelling performance than that of pure gelatin film. The films show good ductility and the elongation at break of the films can be easily adjusted in the range of 1.01–292.19% by adjusting the content of BAE. The films can block ultraviolet light, scavenge the ABTS+ radical, and kill bacteria almost 100%. Significantly, the films showed good pH/NH3 responsiveness as an obvious color change. Comparing with polyethylene film, there was a reduction of around 60.8% in the release of volatile base nitrogen compounds from crucian in storage using RGA5. Overall, these films may be useful for food preservation and real-time quality monitoring

Effect of Dehydrothermal Treatment on the Structure and Properties of a Collagen-Based Heterogeneous Bilayer Membrane

The use of the guided bone regeneration technique in oral surgery has been proven to be an effective method for repairing alveolar bone defects. However, the success of this technique heavily relies on the barrier membrane used. Collagen is the most frequently used raw material to fabricate a resorbable barrier membrane, which has some drawbacks during clinical application, such as poor mechanical properties and rapid biodegradation. To address these issues, a new approach was developed for the preparation of collagen-based heterogeneous bilayer membranes, which involves a combination of physical treatment and biocompatible chemical cross-linking. The dialdehyde carboxymethyl cellulose was used to cross-link collagen to fabricate the membrane, and dehydrothermal (DHT) treatment was applied to enhance its properties. The results showed that DHT treatment apparently improved the structure stability and compression strength in both dry and swollen states. The biodegradation rate of the bilayer membrane was depressed, and the porosity was improved by dehydrogenation. The bilayer membrane was found to have good cytocompatibility. Moreover, the compact lower layer of the bilayer membrane possessed a strong barrier function to fibroblasts while the loose upper layer was able to enhance the adhesion, proliferation, and osteogenic differentiation of osteoblasts. Overall, the collagen-based heterogeneous bilayer membrane has great potential for the application in guided bone regeneration. For the membrane, the improved mechanical properties, reduced biodegradation rate, and enhanced osteoblast response make it a promising material for oral surgery applications