Synthesis, Characterizations and Biocompatibility of Novel Block Polyurethanes Based on Poly(lactic acid) (PLA) and Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB)

Abstract

Alternating and random block polyurethanes (abbreviated as PULA-alt/ran-3/4HB respectively) based on biodegradable polyester poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) were synthesized using 4,4′-methylene bis(cyclohexylisocyanate) (HMDI) as coupling agent and stannous octanoate (Sn(Oct)2) as catalyst. The chemical structure, molecular weight and thermal properties were characterized by FTIR, 1H NMR, GPC, DSC and TGA. Hydrophilicity was investigated by static contact angle of deionized water and CH2I2, while the mechanical behaviors were studied by tensile testing. Their shape-memory behaviors were investigated as a function of PLA molecular weight. The lowest recovery and glass transition temperatures (T g) which approach body temperature, have shown considerable prospect in medical applications. A platelet adhesion study illustrated that PULA-alt-3/4HB possesses better hemocompatibility due to its evident surface microstructure. The cell culture assay demonstrated that the materials are well suited for cell growth and proliferation of rat aortic smooth muscle cells (RaSMCs) and the RaSMCs are more favorable for attachment on PLA-alt-3/4HB materials. Porous scaffold rat implantation indicates non-toxic to animals of the synthesized block polyurethanes.