基于PLA的形状记忆聚酯嵌段聚氨酯的相分离行为

Segmented Polyurethanes Based on Poly(L-lactide):A Phase Separation Study

以2,4-甲苯二异氰酸酯(TDI)为封端剂,乙二醇(EG)为扩链剂通过2步法合成了一系列具有不同聚丙交酯(PLA)分子量和不同TDI-EG链段长度的聚丙交酯嵌段聚氨酯(PLA-PU)。其中,PLA的分子量从1 500到9 500,PLA、TDI和EG的摩尔比从1:2:1至l:7:6。通过DSC和WAXD等测试技术对材料的两相分离程度进行了研究。结果发现,PLA-PU的相分离程度与样品的热历史具有密切的关系,样品中PLA的分子量和TDI-EG长度对于材料的相分离速率和相分离结构的完善程度具有较大的影响。

A series of segmented poly （L-lactide）-polyurethanes （PLA-PU） were synthesized via 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 molecular mass （Mn ） of the PLA was 1 500 - 9 500, and the molar ratio of PLA/TDI/EG was from 1： 2： l to 1： 7： 6. The degree of phase separation in the PLA-PUs was examined as a function of their composition and thermal history with differential scanning calorimetry and wide-angle X-ray diffraction（WAXD）. The results show that the thermal history has an impotant impact on the degree of phase separation in PLA-PUs, and the molecular mass of the PLA segments and the length of the TDI-EG segments have evident influence on the rate and perfection of the phase separation.