Urushiol-Based Benzoxazine Containing Sulfobetaine Groups for Sustainable Marine Antifouling Applications

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.

Sustainable Coating Based on Zwitterionic Functionalized Polyurushiol with Antifouling and Antibacterial Properties

Zwitterionic polymer coatings facilitate the formation of hydration layers via electrostatic interactions on their surfaces and have demonstrated efficacy in preventing biofouling. They have emerged as a promising class of marine antifouling materials. However, designing multifunctional, environmentally friendly, and natural products-derived zwitterionic polymer coatings that simultaneously resist biofouling, inhibit protein adhesion, exhibit strong antibacterial properties, and reduce algal adhesion is a significant challenge. This study employed two diisocyanates as crosslinkers and natural urushiol and ethanolamine as raw materials. The coupling reaction of diisocyanates with hydroxyl groups was employed to synthesize urushiol-based precursors. Subsequently, sulfobetaine moieties were introduced into the urushiol-based precursors, developing two environmentally friendly and high-performance zwitterionic-functionalized polyurushiol antifouling coatings, denoted as HUDM-SB and IPUDM-SB. The sulfobetaine-functionalized polyurushiol coating exhibited significantly enhanced hydrophilicity, with the static water contact angle reduced to less than 60°, and demonstrated excellent resistance to protein adhesion. IPUDM-SB exhibited antibacterial efficacy up to 99.9% against common Gram-negative bacteria (E. coli and V. alginolyticus) and Gram-positive bacteria (S. aureus and Bacillus. sp.). HUDM-SB achieved antibacterial efficacy exceeding 95.0% against four bacterial species. Furthermore, the sulfobetaine moieties on the surfaces of the IPUDM-SB and HUDM-SB coatings effectively inhibited the growth and reproduction of algal cells by preventing microalgae adhesion. This zwitterionic-functionalized polyurushiol coating does not contain antifouling agents, making it a green, environmentally friendly, and high-performance biomaterial-based solution for marine antifouling.