Interdigitation as an Emerging Paradigm for Preparing Sustainable Products from Cellulosic Fibers and Nanocellulose

Growing environmental concerns associated with non-renewable and persistent materials have intensified the search for sustainable alternatives, with cellulosic fibers and nanocellulose emerging as promising candidates. This review examines diverse product opportunities where interdigitation plays a critical role, including nanopaper and barrier films, wet wipe technologies, spun cellulose-based yarns, hydrogels, and composite materials. Particular emphasis is placed on the interplay between colloidal stability, fibrillar alignment, hydrogen bonding, and time-dependent network evolution in governing material performance. Additionally, emerging strategies such as hydroentanglement, ice-templating, in situ crosslinking, and post-formation modification are discussed as means to optimize interdigitated structures. The article further explores how conventional papermaking processes may be reimagined to better exploit interdigitation through innovations in fiber dispersion, alignment, and controlled crosslinking. Interdigitation is presented not as a discrete processing tool but as a unifying framework for understanding and engineering hierarchical cellulose networks. By leveraging the inherent fibrillar nature of cellulose and the dynamics of self-assembly, this paradigm offers new pathways towards the development of next-generation, high-performance, bio-based products that contribute to a circular economy.