A binder-free method to produce heat-sealable and transparent cellulose films driven by a confined green solvent

Abstract

Following global trends in launching plastic bans driven by the increasing problem of non-degradable plastic polluting the environment, cellulose as an abundant natural polymer has gradually been exploited as an eco-friendly material. Nevertheless, there are two challenging problems to overcome: it is hard to dissolve and heat seal (self-bonding under heat and pressing) cellulose, which hinder cellulose materials from replacing plastic. Here, a binder-free method is proposed to realize the bonding of cellulose film without any other binders. The heat-sealable cellulose film was fabricated with a low bonding temperature of 78 °C and high transparency of 90%. Furthermore, glycerol and sorbitol were introduced in the cellulose film not only to reduce the brittleness of the films but also to assist the confined-solvent-driven process. Possible mechanisms of self-bonding and for the tunable concentration range of the residual solvent, which was crucial for the self-bonding, are reported. Additionally, a sealed cellulose-based band and bags were successfully made, indicating the potential of our heat-sealable cellulose films to overcome the inherent limitations of cellulose and boost the potential use of cellulose films as candidates to replace plastic.