Phase Organization and Circularity in PLLA/Vitrimer Semi-interpenetrating Polymer Networks

We investigated, for the first time, the properties of semi-interpenetrating polymer networks (semi-IPNs) formed by curing a vitrimeric biobased covalent adaptable network (CAN) resin, labeled DOM-MVL, in the presence of PLLA. Three semi-IPNs with PLLA:DOM-MVL weight ratios of 80:20, 65:35, and 50:50 were developed. The 80:20 and 65:35 semi-IPNs exhibited a single glass transition temperature (Tg), whose value was between those of pure CAN (31 °C) and pure PLLA (60 °C). In contrast, the 50:50 semi-IPN exhibited a broad Tg, with a midpoint at 28 °C, attributed to the presence of uncured resin acting as a plasticizer in the PLLA phase. In the 65:35 semi-IPN, the presence of the CAN phase significantly inhibited PLLA crystallization. Conversely, the 50:50 sample exhibited a wider crystallization window and enhanced crystallization potential of the PLLA phase consistent with the presence of residual resin acting as a plasticizer. Scanning electron microscopy, conducted after PLLA removal, revealed a porous network with voids corresponding to previously PLLA crystalline domains. All semi-IPNs were mechanically reprocessed via hot pressing, and the feasibility of separating and recovering both components was demonstrated.