Polyurethanes are commonly used as shape memory materials due to their micro‐phase separation structure. The degree of micro‐phase separation is the key factor in the shape memory properties of materials. In this study, the shape memory polyurethane (SMPU) elastomer was prepared based on polycaprolactone diols, isophorone diisocyanate, and 1, 4‐butanediol. And the branched structure is introduced by glycerol and hexamethylene diisocyanate to increase the degree of micro‐phase separation. Moreover, nano‐ZnO is also used to enhance micro‐phase separation. Atomic force microscopy images clearly show that the nano‐ZnO disperses uniformly in the polymer matrix and leads to significant change in the phase structure of SMPU. Dynamic mechanical analysis results indicate that the SMPU/ZnO nanocomposites possess two phase transition above 0°C, one is the melting transition of the soft segments, which is near the body temperature, and the other is the glass transition of hard segments. And with the addition of nano‐ZnO, the difference in transition temperature between the hard and the soft segments is significantly increased. The relationship between shape memory properties and the micro‐phase separation is explored and discussed. In vitro biocompatibility studies show that the SMPU/ZnO nanocomposites have good biosafety. Therefore, the obtained bionanocomposites have the potential application prospect as smart biomaterials.

中文翻译：

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由聚氨酯/ ZnO纳米颗粒组成的形状记忆复合材料作为潜在的智能生物材料

聚氨酯由于其微相分离结构而通常用作形状记忆材料。微相分离的程度是影响材料形状记忆性能的关键因素。在这项研究中，形状记忆聚氨酯（SMPU）弹性体是基于聚己内酯二醇，异佛尔酮二异氰酸酯和1，4-丁二醇制备的。甘油和六亚甲基二异氰酸酯引入了支链结构，以增加微相分离的程度。此外，纳米ZnO还用于增强微相分离。原子力显微镜图像清楚地表明，纳米ZnO在聚合物基质中均匀分散，并导致SMPU相结构发生重大变化。动态力学分析结果表明，SMPU / ZnO纳米复合材料在0°C以上具有两个相变，一个是接近人体温度的软链段的熔融转变，另一个是硬链段的玻璃化转变。随着纳米ZnO的加入，硬链段和软链段之间的转变温度差异大大增加。探索并讨论了形状记忆特性与微相分离之间的关系。体外生物相容性研究表明，SMPU / ZnO纳米复合材料具有良好的生物安全性。因此，所获得的生物纳米复合材料作为智能生物材料具有潜在的应用前景。