Supercritical CO₂-assisted processing of PLA/PBAT blends with β-cyclodextrin/caffeic acid inclusion complexes: Mass transport modeling and disintegration

Abstract

The engineering of polymeric composite foams with tailored cellular architecture remains a critical challenge for sustainable active packaging. In this study, PLA/PBAT composite foams were developed via a sequential supercritical CO₂ (scCO₂) impregnation and foaming. Caffeic acid (CA) was incorporated as the active antioxidant molecule, while β-cyclodextrin (β-CD) served as the host molecule to form inclusion complexes (IC) aimed at modulating functional performance. To evaluate potential polymer degradation during processing, intrinsic viscosity was monitored on the neat matrices from pellet to final foam, while the mechanical stability of both neat and active films and foams was determined via tensile testing. CA release kinetics were evaluated to determine how matrix structural and morphological modifications influence the diffusion mechanisms governing active compound migration. A comprehensive phenomenological mass transport model originally developed for dense systems effectively described CA in these three-dimensional porous architectures without requiring structural modifications. The model identified the bulky IC structure, coupled with matrix tortuosity, as the primary rate-controlling barrier that physically restricts solute diffusion and extends equilibrium times up to ~200h. Furthermore, the foamed composites exhibited significant antioxidant activity and a disintegration profile under controlled composting conditions (ISO 20200) governed by cellular morphology and PBAT content. Building upon previously established cellular morphologies, this study provides a unified engineering framework linking sequential scCO₂ processing, material functionalization, predictive mass transport modeling, and disintegration performance for the design of biodegradable active materials.