Fabrication of Water-Based Alcoholized Poly(butylene succinate-co-adipate) Submicron Particles as Green Coating Agents for Sustainable Paper Packaging

This work aims to fabricate the water-based suspension of poly(butylene succinate-co-adipate) (PBSA) particles by an oil-in-water emulsion technique for use as coating agents to enhance paper-based packaging performances and sustainability. A commercial PBSA resin is functionalized by sizing down an approach via microwave-assisted alcoholysis using propylene glycol (PG). The effect of PBSA/PG feed ratio on the structures, properties, and particle formability of the alcoholized (aPBSA) products is examined. 1H NMR results reveal that the average molecular weight of the aPBSA product decreases to half that of neat PBSA when using a ratio of 24:1 and further decreases to a quarter at 6:1. By using small-size aPBSA, the obtained water-based particles show high stability due to high hydroxyl content and poly(vinyl alcohol) assistance. The suspension is then sprayed on a kraft paper substrate and heated at 60 and 100 degrees C. SEM results reveal that the submicron aPBSA particles penetrate the paper matrix, filling the paper's pores and forming a protective, smooth layer on the paper surfaces. The coated paper shows high water resistance (Cobb60 value of 19.6 g/m2) and water vapor transmission rate (1160 g/(m2 day)). In addition, the aPBSA-coated layers do not impede the paper's repulping and recycling processes, making it a promising solution for improving the sustainability of paper-based packaging.