Silver J H, Myers C W, Lim F, Cooper S L
Department of Chemical Engineering, University of Wisconsin, Madison 53706.
Biomaterials. 1994 Jul;15(9):695-704. doi: 10.1016/0142-9612(94)90168-6.
The physical properties and haemocompatibility of polyurethanes containing polyethylene oxide (PEO) of varying molecular weights but constant weight fraction of hard segment are investigated. The PEO molecular weights studied were 600, 1450 and 8000. Analysis of polyurethane phase separation and crystallinity using dynamic-mechanical analysis and differential scanning calorimetry show that the degree of phase separation and crystallinity increase with polyol molecular weight, but level off at the highest molecular weights. The degree of water absorption increases substantially with increasing PEO molecular weight, levelling off at the highest molecular weight. Tensile data show a maximum in extensibility at a polyethylene glycol (PEG) molecular weight of 1450, while ultimate strength increases with increasing segment length. When the materials are hydrated, there is a significant drop in the modulus, ultimate stress and ultimate elongation. Dynamic contact angle measurements show that surface hydrophobicity decreases as the soft segment molecular weight increases. Using electron spectroscopy for chemical analysis (ESCA) to determine the surface composition of these polyurethanes, it was found that the hard segment content at the surface increases as the polyol block length decreases. The haemocompatibility of these polyurethanes was investigated in an ex vivo canine blood-contacting model. Only for the shortest block length studied, PEG-600, are differences in blood compatibility observed. This material was found to be the most thrombogenic. The PEG-1450 sample shows comparable blood compatibility to PEG-8000.
研究了硬链段重量分数恒定但聚环氧乙烷（PEO）分子量不同的聚氨酯的物理性能和血液相容性。所研究的PEO分子量分别为600、1450和8000。使用动态力学分析和差示扫描量热法对聚氨酯的相分离和结晶度进行分析，结果表明，相分离程度和结晶度随多元醇分子量的增加而增加，但在最高分子量时趋于平稳。吸水率随PEO分子量的增加而大幅增加，在最高分子量时趋于平稳。拉伸数据显示，聚乙二醇（PEG）分子量为1450时，伸长率达到最大值，而极限强度随链段长度的增加而增加。当材料水合时，模量、极限应力和极限伸长率会显著下降。动态接触角测量表明，表面疏水性随软链段分子量的增加而降低。使用化学分析电子能谱（ESCA）来确定这些聚氨酯的表面组成，发现表面硬链段含量随多元醇嵌段长度的减小而增加。在体外犬类血液接触模型中研究了这些聚氨酯的血液相容性。仅在所研究的最短嵌段长度（PEG - 600）下观察到血液相容性存在差异。发现这种材料的血栓形成性最强。PEG - 1450样品的血液相容性与PEG - 8000相当。
