Electro-activated surface micropattern tuning for microinjection molded electrically conductive shape memory polyurethane composites
Electro-activated surface micropattern tuning for microinjection molded electrically conductive shape memory polyurethane composites
复制标题
用于微注射成型导电形状记忆聚氨酯复合材料的电激活表面微图案调谐
DOI：
10.1039/c3ra43640c
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发表时间：
2013-01-01
期刊：
影响因子：
3.9
通讯作者：
Xia, Hesheng
中科院分区：
文献类型：
--
作者：
Fei, Guoxia;Tuinea-Bobe, Cristina;Xia, Hesheng
具有表面微图案的形状记忆聚合物对高价值应用的需求日益增长，例如可调节的附着表面、用于细胞培养研究的动态微几何形状和可切换的信息载体。近年来，微注射成型技术已经成为一种利用多种聚合物高精度制造表面微特征器件的有效方法。本研究采用双螺杆熔体挤出法制备了形状记忆聚氨酯-碳纳米管复合材料，并对其进行了微注射成型，得到了具有表面微图案的构件。然后开发了一种电激活表面微图形调谐系统，该系统可以通过施加电流来加热元件，从而恢复元件在热变形后的原始微图案化表面。为了优化该工艺，本文对微注射成型微零件的导电性、微零件表面形状记忆微图形在退火热处理过程中的保持性、微零件热处理后的宏观面积收缩等三个关键问题进行了研究。研究发现，由于微注射过程中普遍存在的高剪切速率，微注射制品的导电率相对较低。退火处理可将电导率提高几个数量级，但可能会损害微图案的尺寸稳定性，这在很大程度上取决于微注射成型参数，特别是模具温度。提高模具温度、熔体温度、注射速度和注射压力可以更好地保持微图形，并在退火处理过程中提高尺寸稳定性。这项工作展示了微注射成型导电形状记忆聚合物复合材料的电激活表面微图形控制的潜力，该技术可能在电可调粘接、信息存储和防伪技术等一系列应用领域中具有广阔的应用前景。
Shape memory polymers with surface micropatterns have seen rising demand for high value applications such as adjustable adherence surfaces, dynamic micro-geometries for cell culture studies and switchable information carriers. Recently, microinjection molding has emerged as an efficient way to manufacture devices which contain surface micro-features using a wide range of polymers with high accuracy. In this study, shape memory polyurethane–carbon nanotube composites were prepared by twin-screw melt extrusion and subsequently processed using microinjection molding to obtain components with surface micropatterns. Then an electro-activated surface micropattern tuning system was developed which could recover the original micropatterned surface of the components after a thermal deformation by applying a current which heats the component using resistive heating. In order to optimize the technique, three key areas were investigated in this work: conductivity of the microinjection molded microparts, the retention of shape memory micropatterns on the surface of microparts during annealing treatment, and the macroscopic area shrinkage of microparts after thermal treatment. It has been found that the electrical conductivity of microinjection molded parts is relatively low due to the high shear rates prevalent in the process. An annealing treatment improves the electrical conductivity by several orders of magnitude, but can be detrimental to the dimensional stability of the micropatterns, which depends significantly on the micro-injection molding parameters, especially the mold temperature. Increasing the mold temperature, melt temperature, injection speed and injection pressure result in better retention of the micropattern and improved dimension stability during annealing treatment. This work demonstrates the potential of electro-activated surface micropattern control for microinjection molded electrically conductive shape memory polymer composites, which could be a promising technology for a range of application areas including electro-adjustable adherence, information storage, and anti-counterfeiting technology.