Department of Applied Chemistry, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
ACS Appl Mater Interfaces. 2020 Jun 17;12(24):27518-27525. doi: 10.1021/acsami.0c06853. Epub 2020 Jun 4.
High water content is hard to be achieved in conductive hydrogels because a mass of conductive constituent is needed to form an internal conductive pathway. Here, we developed anisotropic electrically conductive hydrogels with high water content based on bacterial cellulose (BC). Polystyrene sulfonate (PSS) was grafted to the acryloyl chloride-modified BC to provide a template for the subsequent synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT). The BC--PSS/PEDOT hydrogels obtained were electrically conductive owing to the immobilization of PEDOT on the surface of cellulose nanofibers. The hydrogels exhibited an electrical conductivity of 0.24 S cm. Further, they demonstrated suppleness in compression (compiled to external compression stress >2.8 MPa and recoverable), inherent high water content (∼95.0 wt %), and anisotropy (anisotropic index of 4.1 in conductivity) from BC. The incorporation of a thermoresponsive poly(-isopropylacrylamide) (PNIPAAm) hydrogel into the BC--PSS/PEDOT hydrogel demonstrated a uniaxial thermoresponsive actuation with resistance change. The expected size and resistance change were only observed in the direction vertical to the cellulose nanofiber layers. These hydrogels could accommodate further developments in novel tissue engineering scaffolds, implantable biosensors, and smart soft electronic devices.
高含水量很难在导电水凝胶中实现，因为需要大量的导电成分来形成内部导电通路。在这里，我们基于细菌纤维素 (BC) 开发了具有高含水量的各向异性导电水凝胶。聚苯乙烯磺酸盐 (PSS) 接枝到丙烯酰氯改性的 BC 上，为随后合成聚 (3,4-亚乙基二氧噻吩) (PEDOT) 提供了模板。由于 PEDOT 固定在纤维素纳米纤维的表面上，因此获得的 BC-PSS/PEDOT 水凝胶具有导电性。水凝胶的电导率为 0.24 S cm。此外，它们表现出柔韧性（压缩时可承受的外部压缩应力>2.8 MPa 且可恢复）、固有高含水量（约 95.0 wt%）和各向异性（导电性各向异性指数为 4.1），这都源于 BC。将温敏性聚（异丙基丙烯酰胺）（PNIPAAm）水凝胶掺入 BC-PSS/PEDOT 水凝胶中，可实现具有单轴热响应的致动，同时电阻发生变化。仅在垂直于纤维素纳米纤维层的方向上观察到预期的尺寸和电阻变化。这些水凝胶可以进一步开发用于新型组织工程支架、可植入生物传感器和智能软电子设备。
