(636f) Controlling Moisture Sensitivity in Cellulose-Based Films

Petroleum-based plastics are ubiquitous in society, but their limited recyclability and slow degradation present significant environmental concerns. In fact, most plastic waste is not recycled but instead discarded to landfills or accumulated uncontained in the environment where they persist for many years. Thus, solid waste accumulation, energy consumption, and CO₂ emissions associated with virgin plastic manufacturing have driven extensive research efforts to develop more sustainable alternative materials to traditional plastics. Cellulose is an obvious candidate to substitute or replace petroleum-based plastics due to its natural abundance, renewability, and biodegradability. Consequently, cellulose-based materials have been widely studied for applications such as packaging, composite materials, and printed electronics. However, the physicochemical properties of cellulose and its derivatives are sensitive to moisture and relative humidity, limiting their performance in many applications. Here we show that reducing the amounts of accessible –OH moieties in the material via crosslinking can be used to rather precisely control the materials’ sensitivity to moisture. By utilizing soluble derivatives of cellulose, we aim to achieve greater opportunity for crosslinking compared to cellulose fibers, which are more conformationally restricted due to their semicrystalline nature. Indeed, when crosslinking carboxymethyl cellulose with renewable reactive crosslinkers, the water uptake and permeability in the cellulose materials are inversely related to crosslinker content, allowing us to tune the water vapor transmission rate from approximately 0.01 to 100 g-mm/m²-day. Promisingly, the lowest measured water vapor transmission rates were comparable to poly(ethylene terephthalate) up to at least 65% relative humidity. We thus provide a solution towards more sustainable plastic alternatives and expand the scope of potential applications of cellulose to reduce dependency on petroleum-based plastics.