The inherent brittleness of poly(lactic acid) (PLA) is widely argued to be the major obstacle that hinders its practice as a reliable bio-based substitute of petroleum-based polymers, hence toughening with rubbery materials has become a common solution, but often at the expense of lowered mechanical strength, processibility and degradability. Herein, a processable and self-compatibilizable bio-toughener for PLA was developed based on dynamically crosslinked soybean oils elastomers (SESO-N x ) with sacrificial hydrogen bonds introduced via N -acetylglycine (NA). Rheological investigations into curing kinetics reveal the mitigation of NA on the rapid curing towards denser SESO-N x networks physically crosslinked by H-bonds, characterized with prolonged relaxation time and high modulus. The dynamic crosslinking and reactive features of SESO-N x endow good processibility and compatibilization of its blend with PLA into a droplet-matrix typed polymer blend with well-refined structure. Integrated with 6 wt% NA, SESO-N 6 was demonstrated to super-toughen PLA with a superior ductility (an elongation at break ∼309.5% and impact strength ∼ 10.28 kJ/m 2 ), and a good mechanical robustness (a tensile strength ∼ 48 MPa and Young’s modulus ∼ 850 MPa). The preferential sacrifices of hydrogen bonds upon deformation dissipate energy and contribute to the high toughness while its reversible reformation and the covalent crosslinks that afford structure integrity guarantee the good elasticity, highlighting the synergistic effect of the dual dynamic crosslinks in elastomers on preparation of toughened PLA with satisfactory performance. • Fully bio-elastomer (SESO-N x ) dually crosslinked by adaptable covalent and H-bonds. • H-bonds densified SESO-N x networks with retarded curing kinetics and relaxation. • Dynamic bonds and epoxides grant SESO-N x good processability and compatibilization. • Synergy of dual dynamic crosslinks guarantees superior toughness and strength.
Chen et al. (Thu,) studied this question.