Synthesis and properties of biodegradable supramolecular polymers based on polylactide-block -poly(δ -valerolactone)-block -polylactide triblock copolymers

Abstract

Biodegradable supramolecular polymers (SMPs) are synthesized by the end-functionalization of poly(lactide)-block-poly(δ-valerolactone)-block-poly(lactide) (PLA-PVL-PLA) triblock copolymers with 2-ureido-4[1H]-pyrimidinone (UPy) self-complementary quadruple hydrogen-bonding unites. The end-functionalized PLA-PVL-PLA copolymers exhibit the typical characteristics of thermoplastic elastomers. Thermal, crystallization behavior, crystalline structure and properties of SMPs can be adjusted by changing the length and stereostructure of PLA blocks. The UPy groups retard the crystallization of PLA and PVL blocks, the crystallization of PVL blocks is also depressed by the increasing PLA blocks. Tensile test reveals that the prepared SMPs presents excellent mechanical properties, DMA results indicate that the heat resistance of L-SMPs is better than that of DL-SMPs. Shape memory property of SMPs was also studied, found that recovery ratio of SMPs with PDLLA blocks can reach 100%. The recovery ratio of L-SMPs was depressed as the crystallizable PLLA blocks increase. This study has systemically investigated that effect of the composition, stereostructure, and crystallizability of PLA blocks on the properties of supramolecular polymers, which would provide potential approaches to synthesize the biodegradable supramolecular polymers with tunable properties.