Department of Chemical Engineering, University of Waterloo, Waterloo, ON, Canada.
Department of Chemical Engineering, University of Waterloo, Waterloo, ON, Canada; Institute of Polymer Research, University of Waterloo, Waterloo, ON, Canada; Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, Canada.
J Colloid Interface Sci. 2022 Apr;611:726-738. doi: 10.1016/j.jcis.2021.11.174. Epub 2021 Dec 1.
In recent years, shape memory polyurethanes have gained substantial attention and are targeted for a range of smart and functional materials. In this work, the development of nanocrystalline celluloses (CNCs) enabled polycaprolactone-based shape memory polyurethane biocomposite using an in situ one-pot reactions is reported. The incorporation of up to 10 wt% CNCs resulted in a remarkable enhancement in the tensile strength at yield (from 0.2 MPa to 7.2 MPa), tensile strength at break (167% improvement), and modulus of elasticity (from 3.5 to 139.3 MPa) while maintaining the elongation at break. This was attributed to the simultaneous action of CNCs as a nucleating agent for crystallization and highly compatibilized reinforcing agent of the network. Moreover, the in situ incorporation of CNCs enhanced the shape memory capability of polyurethanes, which enables its employment in functional material applications, such as the biomedical sector. The intimate interfacial adhesion between the CNCs and the polymer matrix, which promoted shape fixating and recovery, was confirmed by fractured surface morphology studies. Rheology characterizations provided strong evidence that the addition of CNCs increased the shape fixity attributed to the stiffness of CNCs below the glass transition temperature (T) compared to the neat PU in conjuncture with the higher T of CNCs. Overall, the developed polymer nanocomposites are appealing materials for biomedical applications.
近年来，形状记忆聚氨酯因其在一系列智能和功能材料中的应用而受到广泛关注。在这项工作中，我们使用原位一锅法制备了纳米纤维素（CNCs）增强的聚己内酯基形状记忆聚氨酯生物复合材料。结果表明，当 CNCs 的含量达到 10wt%时，复合材料的屈服拉伸强度（从 0.2MPa 提高到 7.2MPa）、拉伸断裂强度（提高了 167%）和弹性模量（从 3.5MPa 提高到 139.3MPa）都得到了显著提高，同时断裂伸长率保持不变。这归因于 CNCs 同时作为结晶的成核剂和网络的高度增容增强剂的作用。此外，CNCs 的原位加入增强了聚氨酯的形状记忆能力，使其能够在功能性材料应用中得到应用，如生物医学领域。通过对断裂表面形貌的研究，证实了 CNCs 与聚合物基体之间的界面黏附作用促进了形状固定和恢复。流变学特性研究提供了有力的证据，表明添加 CNCs 增加了形状固定性，这归因于 CNCs 的刚度低于玻璃化转变温度（T），与纯 PU 相比，同时 CNCs 的 T 较高。总的来说，所开发的聚合物纳米复合材料是用于生物医学应用的有吸引力的材料。
