A novel biomass-derived Schiff base waterborne epoxy coating for flame retardation and anti-bacteria

Recent Development of Functional Bio-Based Epoxy Resins

The development of epoxy resins is mainly dependent on non-renewable petroleum resources, commonly diglycidyl ether bisphenol A (DGEBA)-type epoxy monomers. Most raw materials of these thermoset resins are toxic to the health of human beings. To alleviate concerns about the environment and health, the design and synthesis of bio-based epoxy resins using biomass as raw materials have been widely studied in recent decades to replace petroleum-based epoxy resins. With the improvement in the requirements for the performance of bio-based epoxy resins, the design of bio-based epoxy resins with unique functions has attracted a lot of attention, and bio-based epoxy resins with flame-retardant, recyclable/degradable/reprocessable, antibacterial, and other functional bio-based epoxy resins have been developed to expand the applications of epoxy resins and improve their competitiveness. This review summarizes the research progress of functional bio-based epoxy resins in recent years. First, bio-based epoxy resins were classified according to their unique function, and synthesis strategies of functional bio-based epoxy resins were discussed, then the relationship between structure and performance was revealed to guide the synthesis of functional bio-based epoxy resins and stimulate the development of more types of functional bio-based epoxy resins. Finally, the challenges and opportunities in the development of functional bio-based epoxy resins are presented.

Bio-Based Thermosetting Resins: From Molecular Engineering to Intrinsically Multifunctional Customization

Recent years have witnessed a growing interest in bio-based thermosetting resins in terms of environmental concerns and the desire for sustainable industrial practices. Beyond sustainability, utilizing the structural diversity of renewable feedstock to craft bio-based thermosets with customized functionalities is very worthy of expectation. There exist many bio-based compounds with inherently unique chemical structures and functions, some of which are even difficult to synthesize artificially. Over the past decade, great efforts are devoted to discovering/designing functional properties of bio-based thermosets, and notable progress have been made in antibacterial, antifouling, flame retardancy, serving as carbon precursors, and stimuli responsiveness, among others, largely expanding their application potential and future prospects. In this review, recent advances in the field of functional bio-based thermosets are presented, with a particular focus on molecular structures and design strategies for discovering functional properties. Examples are highlighted wherein functionalities are facilitated by the inherent structures of bio-based feedstock. Perspectives on issues regarding further advances in this field are proposed at the end.

Waterborne Intumescent Fire-Retardant Polymer Composite Coatings: A Review

Intumescent fire-retardant coatings, which feature thinner layers and good decorative effects while significantly reducing heat transfer and air dispersion capabilities, are highly attractive for fire safety applications due to their effective prevention of material combustion and protection of materials. Particularly, the worldwide demand for improved environmental protection requirements has given rise to the production of waterborne intumescent fire-retardant polymer composite coatings, which are comparable to or provide more advantages than solvent-based intumescent fire-retardant polymer composite coatings in terms of low cost, reduced odor, and minimal environmental and health hazards. However, there is still a lack of a comprehensive and in-depth overview of waterborne intumescent fire-retardant polymer composite coatings. This review aims to systematically and comprehensively discuss the composition, the flame retardant and heat insulation mechanisms, and the practical applications of waterborne intumescent fire-retardant polymer composite coatings. Finally, some key challenges associated with waterborne intumescent fire-retardant polymer composite coatings are highlighted, following which future perspectives and opportunities are proposed.

All-Natural Immunomodulatory Bioadhesive Hydrogel Promotes Angiogenesis and Diabetic Wound Healing by Regulating Macrophage Heterogeneity

Macrophages are highly heterogeneous and exhibit a diversity of functions and phenotypes. They can be divided into pro-inflammatory macrophages (M1) and anti-inflammatory macrophages (M2). Diabetic wounds are characterized by a prolonged inflammatory phase and difficulty in healing due to the accumulation of pro-inflammatory (M1) macrophages in the wound. Therefore, hydrogel dressings with macrophage heterogeneity regulation function hold great promise in promoting diabetic wound healing in clinical applications. However, the precise conversion of pro-inflammatory M1 to anti-inflammatory M2 macrophages by simple and biosafe approaches is still a great challenge. Here, an all-natural hydrogel with the ability to regulate macrophage heterogeneity is developed to promote angiogenesis and diabetic wound healing. The protocatechuic aldehyde hybridized collagen-based all-natural hydrogel exhibits good bioadhesive and antibacterial properties as well as reactive oxygen species scavenging ability. More importantly, the hydrogel is able to convert M1 macrophages into M2 macrophages without the need for any additional ingredients or external intervention. This simple and safe immunomodulatory approach shows great application potential for shortening the inflammatory phase of diabetic wound repair and accelerating wound healing.

Flame Retardant Coatings: Additives, Binders, and Fillers

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living.