周学昌课题组成果在《Adv. Funct. Mater.》发表

作者: 发布时间: 2024-01-03 浏览次数: [ ]


将导电填料和弹性聚合物材料相结合是开发柔性导体材料的重要途径之一。为获得良好的导电性能和机械性能(如延展性和机械稳定性),通常需要将高含量的导电填料均匀分散于共价交联的聚合物网络中。因此,这类导电复合材料难以降解,导电填料的回收也极其困难,引起电子垃圾的增加以及环境污染问题。

近日,我朋友的老姐2在线观看周学昌教授课题组报道了一种制备高拉伸、可降解、可回收的高导电液态金属复合材料的简便方法。以室温液态金属纳米液滴交联的水凝胶为聚合物基质,液态金属微米液滴或者银微米片为导电填料,获得复合凝胶,再经过简单的干燥脱水处理,制备机械性能优异的导电复合材料。此外,由于以液态金属纳米液滴为交联点,该复合材料能够溶解于碱性水溶液中,而其中的导电填料也可回收利用。相关研究成果发表在Adv. Funct. Mater.(2024, 2308032, https://doi.org/10.1002/adfm.202308032)期刊上,其中2021级硕士研究生钟定玲为论文第一作者,甘田生博士和周学昌教授为共同通讯作者。


复合水凝胶和脱水复合材料的制备与表征

液态金属纳米液滴与引发剂过硫酸铵(APS)协同引发单体2-羟乙基丙烯酸酯(HEA)的聚合,实现在2 min内快速凝胶化,形成聚合物液态金属复合水凝胶(图1a-d)。其中,液态金属纳米液滴通过表面的氧化物与聚合物链形成氢键,能够作为一种物理交联点增强凝胶的机械性能(图1e)。经过干燥处理后,复合材料的机械性能大幅增强,弹性模量和断裂应变从最初的12.7 kPa和340%分别提高到388 kPa和913%(图1f-g)。

   

图1. (a-d)复合水凝胶和脱水复合材料的制备;(e-g)力学性能表征。

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     

导电复合材料的制备与表征

将银微米片作为导电填料引入液态金属纳米液滴交联的水凝胶中,再对所得的复合水凝胶进行脱水处理,即可制得高拉伸性和高导电的复合材料。脱水过程能够提升该复合材料的机械性能,而且,由于脱水引起的体积收缩,复合材料内部的银微米片会被挤压而相互联通,形成导电网络(图2a-d)。该复合材料的最大拉伸率可达到1400%,而电导率可达到1800 S/cm。这种复合材料可作为应变传感器监测人体运动。

以液态金属微米液滴为导电填料制备的复合材料,具有各向异性的双层结构,其中一层富含液态金属微米液滴,而另一层则主要由液态金属纳米液滴交联的聚合物基质所构成(图2e-g)。液态金属微米液滴的加入,提升了复合材料的拉伸性能。在微米液滴富集层一侧施加一定的作用力,可使液滴破坏,液滴内部的液态金属流出,形成导电路径。基于这一特征,可在该复合材料表面书写导电线路,与其他电子元件结合,构建柔性电路。

  

图2.(a-d)以银微米片为导电填料的复合材料的制备与应用;(e-h)以液态金属微米液滴为导电填料的复合材料的制备与应用。


复合材料材料的降解以及导电填料的回收

由于液态金属纳米液滴作为物理交联点,当将复合材料浸没于氢氧化钠(NaOH)水溶液中,液态金属纳米液滴的氧化层会与NaOH反应,破坏了纳米液滴与聚合物链间的氢键,从而破坏该复合材料的交联网络。因此,这些复合材料可以在NaOH水溶液中完全溶解(图3)。而且,其中的导电填料可以分离出来,并且回收利用。液态金属和银微米片的回收率可分别达到79%和95%。

   

图3. (a-b)脱水复合材料的降解;(c-d)导电填料的回收


该研究为开发瞬态可回收柔性电子材料提供了新的思路。该工作得到了国家自然科学基金、广东省自然科学基金以及深圳市基础研究等项目的资助。


论文信息:

D. Zhong, S. Shi, X. Yang, S. Handschuh-Wang, Y. Zhang, T. Gan,* X. Zhou,* Highly Stretchable yet Degradable and Recyclable Conductive Composites with Liquid Metal Nanodroplets as Physical Crosslinks. Adv. Funct. Mater. 2024, 2308032. https://doi.org/10.1002/adfm.202308032


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