Chen Xuesi

Shape-memory and biocompatibility properties of segmented polyurethanes based on poly(L-lactide)

A series of segmented poly(L-lactide)-polyurethanes (PLA-PUs) were synthesized by a two-step method, with oligo-poly(L-lactide) (PLA) as the soft segments and the reaction product of 2,4-toluene diisocyanate (TDI) and ethylene glycol (EG) as the hard segments. The shape-memory properties and biocompatibility of PLA-PUs were examined. The 50% compressed PLA-PUs could recover almost 100% to their original shape within 10°C from the lowest recovery temperature (22°C–37°C). In the recovery process the PLA-PU showed a maximum contracting stress in the range of 1.5–4 MPa. Cell incubation experiments show that PLA-PU has biocompatibility comparable to that of pure PLA. Therefore, this kind of polyurethane can be used for implanted medical devices with shape memory requirements.

Organometallic catalysts for the ring-opening polymerization of lactide

As a novel type of biomaterials, polylactide (PLA) is an important alternative biodegradable material to traditional fossil-based plastics and shows wide applications in green plastics and biomedical field. PLA is commonly synthesized by the ring-opening polymerization of lactide. In this contribution, the discovery of organometallic catalysts for the ring-opening polymerization of lactide is briefly reviewed based on our group’s work. Specifically, the organic compounds with different substitution groups, chirality and metal species are discussed for mononuclear and multinuclear catalysts, and the cooperation effects on the steric hindrance and mutual electron are focused for the multinuclear catalysts.