用于可变形导体和电磁屏蔽的石墨烯-聚氨酯涂料
Graphene-Polyurethane Coatings for Deformable Conductors and Electromagnetic Interference Shielding
摘要：
即使在显著的机械变形下也保持其导电性的导电聚合物材料是致动器电极、适形电磁屏蔽、可拉伸触觉传感器和柔性能量存储所需要的。这些材料面临的挑战是，即使在低应变下，膨胀的导电网络也倾向于分离，导致显着的压阻。本文中，通过用石墨烯-弹性体溶液喷涂腈衬底来制造可变形导体。在数千次弯曲循环和重复折叠-展开事件后，涂层的电阻仅略有增加。可变形导体在12%的应变下使其电阻加倍，并且可清洗而不改变其电性能。通过考虑变形时纳米填料的分离来模拟电导率-应变行为。为了提高在较高应变下的电导率，通过在喷涂之前拉伸腈基质来调整生产工艺，之后将其释放。这种适应意味着电阻在25%应变下加倍。在8-12 GHz电磁波带内，电阻足够低，屏蔽率为1.9 dB/μm。发现柔性导体的物理和电性能（包括EM屏蔽）在循环时劣化，但可以通过重新加热涂层来恢复。
英文摘要：
Electrically conductive, polymeric materials that maintain their conductivity even when under significant mechanical deformation are needed for actuator electrodes, conformable electromagnetic shielding, stretchable tactile sensors and flexible energy storage. The challenge for these materials is that the percolated, electrically conductive networks tend to separate even at low strains, leading to significant piezoresistance. Herein, deformable conductors were fabricated by spray-coating a nitrile substrate with a graphene-elastomer solution. The coatings showed only slight increase in electrical resistance after thousands of bending cycles and repeated folding-unfolding events. The deformable conductors doubled their electrical resistance at 12% strain and were washable without changing their electrical properties. The conductivity-strain behaviour was modelled by considering the nanofiller separation upon deformation. To boost the conductivity at higher strains, the production process was adapted by stretching the nitrile substrate before spraying, after which it was released. This adaption meant that the electrical resistance doubled at 25 % strain. The electrical resistance was found sufficiently low to give a 1.9 dB/μm shielding in the 8-12 GHz electromagnetic band. The physical and electrical properties, including the EM screening, of the flexible conductors, were found to deteriorate upon cycling but could be recovered through reheating the coating.
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