Synthesis and properties of poly(lactide)/poly(ε-caprolactone) multiblock supramolecular polymers bonded by the self-complementary quadruple hydrogen bonding

Alternating poly(lactide)/poly(ε-caprolactone) multiblock supramolecular polymers were synthesized by terminal functionalization of PLA-PCL-PLA triblock copolymers with the self-complementary quadruple hydrogen bonding of 2-ureido-4[1H]-pyrimidinone (UPy) dimers. The prepared supramolecular copolymers (SMPs) show the properties of thermoplastic elastomers, while the PLA-PCL-PLA is brittle solids, which is attributed to the chain extension induced by UPy units. The effects of the length and stereostructures of PLA blocks, and various initiators on the crystallization and melting behaviors, morphological, mechanical, shape memory and self-healing properties of SMPs were systemically investigated. The incorporation of UPy units obviously depresses the crystallization of polymer chains, but SMPs containing POSS could decline the inhibition of UPy units for crystallization due to the heterogeneous nucleation of POSS. The prepared SMPs have poor ordered micro-phase structure. Mechanical, shape memory and self-healing properties of SMPs could also be easily adjusted by the stereostructures and length of PLA blocks. This would provide potential approaches to control the structure and physical performances of PLA-based materials.