Esters of α-1,3-glucan: designed enzymatic polysaccharides as new matrices for sustainable packaging and membrane applications

Enzymatic polymerisation of sucrose creates nature-identical polysaccharides, such as poly α-1,3-glucan, offering a scalable approach to introduce biopolymers into industrial applications. In this study, we explored the solubility, diffusivity, and permeability of various fluids (CO2, O2, liquid and vapour water) in films of α-1,3-glucan and its long-chain acid esters, specifically two glucan palmitates (GP) and one glucan laurate acetate (GLA) with varying degrees of substitution (DoS), highlighting the potential of glucan derivatives in packaging and membrane separation applications. Additionally, we evaluated films' wettability through contact angle measurements and examined dimethyl carbonate as an alternative to chloroform for film production. GP2, the ester with the highest degree of substitution studied here, reached water uptake of ~2 g mm/m2 day at 100% RH, which is 400 times lower compared to the unmodified glucan. CO2 and O2 permeability exhibited patterns seen in cellulose esters, with GPs showing CO2 permeability levels higher than 100 Barrer (3.34 × 10−14 mol m/(m2 s Pa)), promising for CO2 separation in membrane processes. A quantitative correlation between water uptake in glucan- and cellulose-based materials and their structure is provided as a first tool to assess applicability of these materials in processes where water transport is a key factor.