Simultaneously Enhanced Chain Flexibility, Three Dimensional Printability, and Reduction of Shrinkage Stress in Biodegradable and Photocurable Multiblock Copolymers

A library of biodegradable and photocurable poly (propylene fumarate)-co-poly(trimethylene carbonate) (PPF-co-PTMC) multiblock copolymers encompassing the entire composition range and various block lengths has been designed and synthesized. By combining experiments and atomistic molecular dynamics simulations, we reveal the effects of chain architectures such as composition and block lengths on the thermal, rheological, and printing properties of these copolymers. The introduction of flexible PTMC blocks, which are found to be highly miscible with PPF blocks, into the unentangled copolymer backbone dramatically expedites chain relaxation, lowers the activation energy, and enhances the solubility in toluene. The chain flexibility of the copolymers is positively correlated with the composition of PTMC, while the block length of either PPF or PTMC affects little. Thus, lower values in glass transition temperature Tg, zero-shear viscosity eta 0, printing speed, and shrinkage stress in photocuring are consistently seen at higher compositions of PTMC. Photocurable PPF-co-PTMCs can be printed into high-precision 3D objects. This study provides a series of novel biopolymers and also a guideline to design photocurable polymers used in biomedical implants.