Lignin-Based Triple Shape Memory Polymers.

Lignin-based triple shape memory polymers comprised of both permanent covalent cross-links and physical cross-links have been synthesized. A mixing phase with poly(ester-amine) and poly(ester-amide) network having two distinct glass transitions was hot mixed with more structurally homogenized methanol soluble lignin fraction by one-pot, two-step method. Triple shape properties arise from the combined effect of the glass transition of polyester copolymers and lignin and the dissociation of self-complementary hydrogen bonding and cross-link density. The percentage of recovery in each stage was investigated and it was proved that the first recovery is related with lignin-poly(ester-amine) rich network and the second recovery stage is related with lignin-poly(ester-amide) rich network. The thermal and mechanical properties of the lignin-copolymer networks were also investigated using differential scanning calorimetry and dynamic mechanical analysis.