Green chemistry perspectives on click chemistry approaches for cellulose functionalization: a critical review

Abstract

Click chemistry approaches have revolutionized cellulose functionalization, offering environmentally sound alternatives to conventional modification methods. This critical review examines these transformative techniques through a green chemistry lens, providing researchers with a comprehensive assessment of their sustainability and practical utility. We systematically evaluate azide–alkyne cycloaddition, thiol–ene/yne coupling, Diels–Alder reactions, SuFEx chemistry, and the emerging hydroxyl–yne click chemistry against the twelve principles of green chemistry. Our analysis reveals that hydroxyl–yne click chemistry represents a significant breakthrough by enabling direct modification of cellulose's native hydroxyl groups without preliminary functionalization steps, substantially reducing waste generation and processing complexity. Traditional click approaches still offer valuable pathways with distinct advantages for specific applications, particularly when regioselectivity or reversibility is required. However, important research gaps remain, including the need for biobased catalysts, aqueous-compatible reaction systems, and improved scalability. This review provides cellulose researchers with actionable guidance for selecting optimal functionalization strategies based on sustainability criteria, technical requirements, and application needs, accelerating the development of next-generation cellulose materials for a circular bioeconomy.