Exploring potential of cellulose acetate sulfate films for sustainable packaging: tuning characteristics via sulfate group variation

Due to the inherent advantages of cellulose derivatives, there has been a dedicated focus in research to employ them as alternatives to synthetic materials. In this study, we investigated the potential of cellulose acetate sulfate (CAS) for the film fabrication, exploring how the properties of CAS films vary in relation to the number of sulfate groups (DS sulfate ). CAS films with different DS sulfate (0.4, 0.7, and 1.0) were prepared using solvent casting. Despite variations in DS sulfate , all CAS produced transparent and self-supporting films. Nonetheless, the characteristics of CAS films were found to be significantly influenced by their DS sulfate . Owing to the size of sulfate groups, the substitution of these groups induces alterations in the polymer networks present within CAS films. These alterations, combined with the hydrophilic nature of sulfate groups, give rise to distinct variations in the characteristics of films associated with DS sulfate . CAS films with the lowest DS sulfate (0.4) demonstrated superior mechanical properties with an elastic modulus of 2131.6 MPa and tensile strength of 36.7 MPa. Conversely, higher DS sulfate correlated with increased wettability and water vapor permeability (WVP). CAS films with the highest DS sulfate exhibited maximum wettability (43.2°) and WVP (2.58 × 10 –10 g·s −1 ·m −1 ·Pa −1 ). These findings, given the limited research on CAS characteristics, hold the potential to expand horizons in the selection of eco-friendly materials based on cellulose derivatives. Graphical abstract