一种基于有序硬段的可生物降解聚氨酯的制备及性能

以聚乙二醇(PEG,Mn=600、1000)为引发剂,L-丙交酯(L-LA)为单体,在辛酸亚锡存在下开环聚合合成了三嵌段预聚物聚丙交酯-聚乙二醇-聚丙交酯(PLA-PEG-PLA),然后以具有有序结构的二氨基甲酸酯基二异氰酸酯(六亚甲基二异氰酸酯-1,4-丁二醇-六亚甲基二异氰酸酯,HBH)扩链制备了一种可生物降解的脂肪族聚氨酯(PU-I、PU-II)。作为对比,以4,4’-二苯基甲烷二异氰酸酯(MDI)作为扩链剂合成了芳香族聚氨酯(PU-III)。通过核磁共振、红外光谱、超高分辨质谱、凝胶渗透色谱等对预聚物、扩链剂、聚氨酯的化学结构进行了表征。通过对PU-I、PU-II和PU-III膜热性能、力学性能和体外降解性能的对比,研究了有序硬段对聚氨酯性能的影响。结果表明,相对于PU-III,PU-I具有更好的力学性能(断裂强度21 MPa,断裂伸长率840%)和较快的体外降解(19d);随着亲水链段PEG含量的增加,PU膜(PUII)的断裂强度降低,断裂伸长率增加,同时体外降解速率变快。该类型的脂肪族聚氨酯具有降解产物无毒、合适的力学性能和降解性能,可替代传统的芳香族聚氨酯,在医疗行业中有更广泛的用途。

Preparation and Properties of a Biodegradable Polyurethane Based on Uniform-Size Hard Segments

This paper presented a novel polyurethane based on uniform-size hard segments.The prepolymers of poly(L-lactide)-poly (ethylene glycol)-poly (L-lactide) (PLA-PEG-PLA) were synthesized via bulk ring-opening polymerization with PEG (Mn =600,1000) as initiator and L-lactide as monomer.The chains of prepolymers were extended with diurethane diisocyanates based on inexpensive 1,6-hexanediisocyanate to give the aliphatic polyurethane (PU-Ⅰ,PU-Ⅱ),and as a control,the aromatic polyurethane (PU-Ⅲ) was prepared with 4,4'-diphenylmethane diisocyanates (MDI) as chain extender.The chemical structures of diurethane diisocyanates,prepolymer and PU were confirmed by NMR,FT-IR,HR-MS and GPC.The effect of uniform-sized hard segments on the properties was studied by researching the thermal properties,mechanical properties and in vitro degradation properties of PU films.Comparing with PU-Ⅲ,PU-Ⅰ has better mechanical properties (ultimate stress of 21 MPa,elongation at break of 840 ％) and faster degradation rate (19 d).Comparing with PU-Ⅰ,the PU-Ⅱ containing more PEG in the main chain shows lower ultimate stress,higher elongation at break and faster degradation rate.The non-toxic degradation products,suitable mechanical properties and degradation rate of this kind of polyurethane can make them substitutes for MDI-based polyurethanes and use for further biomedical application.