Synthesis, Characterization And Biocompatibility Of Alternating Block Polyurethanes And Random Block Polyurethanes

The thesis is divided into two parts. Firstly, it mainly talking about a series of alternating block polyurethanes (abbreviated as PU3/4HB-alt-PPG-PEG-PPG) based on poly(3-hydroxybutyrate-co-4-hydroxybutrate) and poly(propylene glycol)-poly(ethylene glycol)-poly(propylene glycol) were synthesized via specifically selective coupling reaction between terminal hydroxyl P3/4HB segment and isocyanate group end-caped PPG-PEG-PPG segment. The chemical structure, molecular weight, thermal property and hydrophilicity were respectively determined by nuclear magnetic resonance spectrum ( 1H NMR), fourier transform infrared spectroscopy (FTIR) , gel permeation chromatography (GPC), differential scanning calorimetry (DSC) , thermogravimetric analysis (TGA), static contact angle of H2O and CH2I2. The platelet adhesion assay shows that the obtained polyurethanes have lower platelet adhesion than the raw materials and the amount of platelet adhesion could be controlled by varying the segmental length of P3/4HB-diol. And the cell culture assay reveals that the obtained polyurethanes are cell inert materials and unfavorable for the attachment of mouse fibroblast cell line L929 and rabbit aortic smooth muscle cells (RaSMCs). Secondly, we studied on the differences between alternating and random block polyurethanes based on (P3/4HB or PCL) and PEG prepolymers. 1H NMR, GPC, DSC, TGA, SEM, static contact angle analyzer, microplate reader were applied. The DSC data showes that the alternating block polyurethanes exhibit higer degree of crystallinity (Xc) due to their structural regularity. Static contact angle analysis reveals that the alternating series tend to be more hydrophilic with higher surface free energy. The platelet assay shows that the obtained polyurethanes display better blood compatiblity compared to the raw materials due to their more hydrophilic surface, in which the alternating series have better blood compatiblity. And the cell (L929, RaSMCs and mouse glial cells) culture assay demonstrates that the alternating series display more comfortable cell-compatibility.