大形变电阻稳定的“褶皱网络结构”弹性导体的构建

Elastomeric conducting materials are key components in flexible electronics, which require structurally uniform, highly conductive, and show stable resistance under large deformation. Generally the elastic conductors are prepared by dispersing conducting nanoparticles (such as carbon or metal nanoparticles) into polymer elastomers, to form a uniform and highly conductive “network structure” in the polymer matrix. However, the “network structure” tends to break under large deformation and results in dramatic resistance increase. In order to obtain elastic conductors with stable resistance, a thin layer of conducting materials with “buckled structure” is attached on the surface of the elastomers. The drawback of this structure is that the total conductivity is low and the structure is not uniform. Therefore, it is still a challenge to fabricate elastic conductors which are highly conductive, structurally uniform, highly stretchable and shows stable resistance under large deformations. Our strategy is to introduce the “buckled structure” into the “network structure”, to form a “buckled network structure”. The detailed method is as follows, firstly the elastomers are swollen with metal ion solution; and then the elastomers are stretched and the metal ions are reduced into metal nanoparticles, which form conductive “network structure”; finally the prestrain was released to compress the “network structure” into “buckled network structure”. The proposed research will boost the theoretical research and practical applications in flexible electronics.

高分子弹性导体是柔性电子领域的关键基础材料，理想的弹性导体可在大形变下保持稳定电阻，且结构均一、电导率高。目前常用的制备弹性导体的方法是将导电纳米材料（如碳粉或金属粉）均匀分散到高分子弹性体中，形成结构均一且高电导率的 “网络结构”弹性导体。然而在大形变下，导电网络被破坏，电阻急剧增加。为获得形变下电阻稳定的弹性导体，可将具有“褶皱结构”的导电层铺在弹性体表面制成弹性导体。但是这种材料整体电导率很低，且结构均匀性差。总之，目前缺乏结构均一、形变大、电阻稳定、电导率高的弹性导体的构建方法。我们的研究思路是在高分子导电“网络结构”中，引入“褶皱结构”，形成“褶皱网络结构”弹性导体。具体来讲，是将高分子弹性体浸泡金属盐并对其预拉伸；将金属盐原位还原为金属颗粒并发生相分离形成导电“网络”；释放预拉伸，“网络结构”受到压缩形成“褶皱网络结构”弹性导体。该研究成果将有力推动柔性制造领域的理论与产业化。

高分子弹性导体是柔性电子领域的关键基础材料，理想的弹性导体可在大形变下保持稳定电阻，且结构均一、电导率高。目前常用方法制备的弹性导体在大形变下，导电网络被破坏，电阻急剧增加。因此，目前缺乏结构均一、形变大、电阻稳定、电导率高的弹性导体的构建方法。我们的研究思路是在高分子导电“网络结构”中，引入“褶皱结构”，形成“褶皱网络结构”弹性导体。本项目针对以上问题，研发并取得的结果如下：.1. 基于多孔丙烯酸酯泡绵的网络褶皱结构弹性导体的应用拓展。.本工作采用浸渍法将水性碳纳米管浆料渗透到商业化具有拉伸性的多孔泡绵中。该弹性导体在70%拉伸应变下电阻变化率可以小于2%。同时发现该弹性导体在经过500个拉伸应变为30%的循环之后电磁屏蔽效率稳定在35dB以上。.2. 褶皱结构弹性导体用于传感驱动一体化人工肌肉。我们利用褶皱结构的导体层同时作为该人工肌肉的驱动层、控制层和传感层，为人工肌肉的设计以及向软体机器人方向的整合提供新的思路和方案。.3. 基于各向异性网络结构的弹性导体在电磁屏蔽和无线应变传感器的应用。本项目中我们发现具有各向异性网络结构的弹性导体在拉伸过程中由于接触点的增加，电阻反而有可能减小，这对于对抗拉伸过程中电学性能的自然衰减具有重要的意义。基于此类弹性导体制备的电磁屏蔽材料和双偶极子天线在拉伸应变下的效能稳定系数为0.85，优于多种文献报道的弹性导体。.除此之外，我们还致力于将弹性导体与驱动器、人工肌肉、扭热制冷的用途结合起来，开展新一代柔性智能设备的基础应用研究，例如纤维扭热制冷、压敏传感器、人工肌肉和驱动器等。取得的成果发表在Science, Nat. Comm., Adv. Mater.， Adv. Sci.， Accounts of Chemical Research.， Adv. Funct. Mater.， J. Mater. Chem. A,，Mater. Horiz., Chemical Engineering Journal, Carbon, 并申请了3项专利。该研究成果将有力推动柔性制造领域的理论与产业化。