Zheng Yu, Dong Renqiong, Shen Jiabin, Guo Shaoyun
Polymer Research Institute of Sichuan University , State Key Laboratory of Polymer Materials Engineering, Chengdu, Sichuan 610065, PR China.
ACS Appl Mater Interfaces. 2016 Jan 20;8(2):1371-80. doi: 10.1021/acsami.5b10246. Epub 2016 Jan 8.
Shape memory materials containing alternating layers of thermoplastic polyurethane (TPU) and polycaprolactone (PCL) were fabricated through layer-multiplying extrusion. As a type of special co-continuous morphology, the multilayer structure had stable and well-defined continuous layer spaces and could be controlled by changing the number of layers. Compared with conventional polymer blends, the multilayer-assembled system with the same compositions had higher shape-fixing and -recovery ratios that could be further improved by increasing the number of layers. By analyzing from a viscoelastic model, the deformation energy preserved in elastic TPU layers would be balanced by adjacent PCL layers through interfacial shearing effect so that each component in the multilayer structure was capable of endowing the maximum contribution to both of the shape-fixing and -recovery stages. Besides, the influence of the hardness of TPU layers and the morphology of PCL layers were respectively concerned as well. Results revealed that choosing low-hardness TPU or replacing neat PCL layers by TPU/PCL blend with co-continuous morphology were beneficial to achieving outstanding shape memory performances.
通过层倍增挤出法制备了包含热塑性聚氨酯（TPU）和聚己内酯（PCL）交替层的形状记忆材料。作为一种特殊的共连续形态，多层结构具有稳定且明确的连续层间距，并且可以通过改变层数来控制。与传统聚合物共混物相比，具有相同组成的多层组装体系具有更高的形状固定率和回复率，通过增加层数可以进一步提高。从粘弹性模型分析可知，弹性TPU层中保留的变形能将通过界面剪切效应由相邻的PCL层平衡，从而使多层结构中的每个组分都能够在形状固定和回复阶段做出最大贡献。此外，还分别研究了TPU层硬度和PCL层形态的影响。结果表明，选择低硬度TPU或用具有共连续形态的TPU/PCL共混物替代纯PCL层有利于实现优异的形状记忆性能。
