侧链为光敏感基团的可生物降解聚氨酯的合成及表征

设计合成2-甲基-2-肉桂酰氧甲基-1,3-丙二醇(MCO)作为扩链剂,并以聚乳酸二醇(PLA diol)为软段,异佛尔酮二异氰酸酯(IPDI)和MCO为硬段制备了一系列侧链含有肉桂基团的可生物降解聚氨酯.结果表明MCO具有较高的反应活性,可满足制备高分子量聚氨酯的要求.聚氨酯结构中的肉桂双键可在紫外光和光引发剂的共同作用下,发生快速的交联反应,短时间内形成交联结构.软段结构相同时,凝胶含量随MCO含量的增加而增加.硬段结构相同时,凝胶含量随软段分子量的增加而减少.适度的交联可提高拉伸强度和形变回复率.

SYNTHESIS AND CHARACTERIZATION OF BIODEGRADABLES POLYURETHANE CONTAINING LIGHT SENSITIVE SIDE GROUPS

2-Methyl-2-cinnamoyloxymethyl-1,3-propanediol(MCO) as a chain extender was prepared.Polylactide diol(PLA diol) as soft segment,isophorone diisocyanate(IPDI) and MCO as hard segment were used to synthesize biodegradable polyurethane(PU) containing light sensitive groups.The properties of the PUs obtained were characterized by nuclear magnetic resonance hydrogen spectrum(1H-NMR),Fourier transform infrared spectroscopy(FTIR),gel permeation chromatography(GPC),differential scanning calorimetry(DSC) and tensile testing.The results showed that MCO had high enough reactivity to obtain the PUs of high molecular weight,the number average molecular weight of PUs ranged from 41.9×103 to 79.0×103.Crosslinking of the PUs was realized by irradiating the PU solution with UV 365 nm light.The time for complete crosslinking of PU in solutions in the absence of light initiator(2-hydroxy-2-phenylacetophenone) was 25 min,but it was only 5 min in the presence of light initiator.The gel content increased with increasing MCO content in PUs when the PUs had the same soft segment;the gel content decreased with increasing soft segment molecular weight when the PUs had the same hard segment.Rational crosslinking contributed to the increase of tensile strength and shape recovery ratio,the shape recovery ratio of PU reached nearly 100%.