A cellulose nanocrystals/tung oil-based multifunctional polymer with good mechanical properties, thermal stability, adhesive, self-healing, and recyclable properties

The vigorous development of dynamic covalent chemistry has inspired the study of dynamic covalent disulfide bond materials. However, the low bond energy of the disulfide bond leads to weak mechanical properties of polymers. Developing polymers with both self-healing and good mechanical properties is still a huge challenge. Herein, a novel fully bio-based multifunctional polymer (TCNC/TO) was designed by thioctic acid (TA), tung oil (TO), and cellulose nanocrystals (CNC). Tung oil (TO) was used as a cross-linking agent and free radical quenching agent. CNC was reacted with thioctic acid (TCNCs) as a reinforcing agent to enhance mechanical properties of TCNC/TO. The fully bio-based TCNC/TO exhibits promising self-healing ability (95% healing efficiency) and good mechanical properties (250% increase in tensile strength compared with polymers without CNC). Even after 10 cyclic tensile tests, the mechanical properties of TCNC/TO are not damaged. Furthermore, TCNC/TO possesses outstanding recyclability (still shows certain mechanical properties after repeated recycling) and adhesion (high adhesive strength towards various substrates). These impressive performances make TCNC/TO a candidate in the field of self-healing materials and adhesives.