Development and Mechanism of High-Performance Fully Biobased Shape Memory Benzoxazine Resins with a Green Strategy

Developing high-performance fully biobased shape memory thermosets with a green strategy is a challenging topic of great interest. Herein, two unique fully biobased benzoxazine resins with excellent shape memory properties, denoted as poly(IE-dea) and poly(G-dea), were developed by synthesizing two fully biobased benzoxazine monomers (IE-dea and G-dea) using a solvent-free method. The thermal, mechanical, and shape memory properties of poly(IE-dea) and poly(G-dea) were studied. Among the fully biobased shape memory polymers reported so far, poly(IE-dea) and poly(G-dea) have the highest glass transition temperatures (138 and 216 degrees C), initial thermal decomposition temperatures (340 and 347 degrees C), and tensile strengths (85.1 +/- 2.5 and 65.9 +/- 2.7 MPa). In addition, poly(IE-dea) and poly(G-dea) exhibit excellent shape memory properties. After four shape memory cycles, their shape fixity ratios are 97.7-98.0% and 96.7-97.2%, respectively, and their shape recovery ratios are 96.7-97.2% and 93.0-93.4%. In fact, shape memory benzoxazine resins up-to-date. The mechanism behind the excellent integrated performances of poly(IE-dea) and poly(G-dea) results from unique integrated actions of the flexible decane segment and rigid cross-linked structure from the polymerization of oxazine rings.