Effect of Chain Extender on Hydrogen Bond and Microphase Structure of Biodegradable Thermoplastic Polyurethanes

摘要

Thermomechanical properties of polyurethanes(PUs) strongly depend on the molecular interactions and microphase structure. In this work, two chain extenders with different ratios, flexile 1,4-butanediol(BDO) and branched trimethylolpropane mono allyl ether(TMPAE), are used to tune the molecular interactions and microphase structures of a series of biodegradable thermoplastic polyurethanes(TPUs). In TPUs, the biodegradable polycaprolactone(PCL, M_n of 2000) is used as soft segment while 1,6-diisocyanatohexane(HDI) and chain extenders are used as hard segment. Fourier transform infrared spectroscopy(FTIR), proton nuclear magnetic resonance spectroscppy(~1 H-NMR), gel permeation chromatography(GPC), differential scanning calorimetry(DSC), dynamic mechanical analysis(DMA) and mechanical tests were performed to characterize the bulk structure and properties of TPUs. Compared with BDO, the steric bulk of TMPAE is larger. The increment of TMPAE can help to increase the hydrogen bond content, microphase separation, and the elastic modulus ratio(R), which would strongly affect the thermomechanical property of the TPUs. The results of this work verify the importance of the structure of chain extender on the properties of TPUs. It provides valuable information for further understanding the structure-property relationships of these polyurethanes.