Effect of Water Vapor Adsorption on Electrical Properties of Carbon Nanotube/Nanocrystalline Cellulose Composites
Effect of Water Vapor Adsorption on Electrical Properties of Carbon Nanotube/Nanocrystalline Cellulose Composites
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DOI：
10.1021/acsami.6b02374
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发表时间：
2016-04-13
影响因子：
9.5
通讯作者：
van de Ven, Theo G. M.
中科院分区：
文献类型：
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作者：
Safari, Salman;van de Ven, Theo G. M.
人们早就知道，纤维素的电学性质很大程度上受水蒸气吸附的影响。在纤维素基质中加入导电纳米纤维是定制其特性以用于电子和传感设备的方法的一个例子。在这项工作中，我们介绍了两种新的纳米复合材料，包括碳纳米管（CNTs）和传统的或电稳定的纳米晶体纤维素基质。传统的纳米晶纤维素（NCC）由刚性结晶骨架组成，而电稳定纤维素（ENCC）由刚性结晶骨架和两端突出的羧化聚合物组成。通过调整碳纳米管负载，我们可以定制对环境相对湿度具有最小电灵敏度的碳纳米管/NCC复合材料，尽管复合材料具有高吸湿性。在水蒸气吸附时，碳纳米管电导率的预期下降是由于电子的捐赠，而在最佳碳纳米管负载（1-2%）下，由于质子跳变，NCC的电导率增加，从而抵消了这一预期的下降。与CNT/NCC复合材料相反，CNT/ENCC复合材料在1% CNT负载下，在相对湿度高达75%时表现出绝缘行为，此后复合材料变得导电。这种有趣的行为可以归因于在低和中等相对湿度下，由于ENCC上的羟基数量有限，羧基之间形成氢键，使得ENCC具有有限的水分子吸附位点，因此ENCC的吸湿率很低。
It has been long known that the electrical properties of cellulose are greatly influenced by adsorption of water vapor. Incorporating conductive nanofibers in a cellulose matrix is an example of an approach to tailor their characteristics for use in electronics and sensing devices. In this work, we introduce two new nanocomposites comprising carbon nanotubes (CNTs) and conventional or electrosterically stabilized nanocrystalline celluloses matrices. While conventional nanocrystalline cellulose (NCC) consists of a rigid crystalline backbone, electrosterically stabilized cellulose (ENCC) is composed of a rigid crystalline backbone with carboxylated polymers protruding from both ends. By tuning CNT loading, we can tailor a CNT/NCC composite with minimal electrical sensitivity to the ambient relative humidity, despite the fact that the composite has a high moisture uptake. The expected decrease in CNT conductivity upon water vapor adsorption, due to electron donation, is counterbalanced by an increase in the conductivity of NCC due to proton hopping at an optimum CNT loading (1-2%). Contrary to the CNT/NCC composite, a CNT/ENCC composite at 1% CNT loading shows insulating behavior for relative humidities up to 75%, after which the composite becomes conductive. This interesting behavior can be ascribed to the low moisture uptake of ENCC at low and moderate relative humidities due to the limited number of hydroxyl groups and hydrogen bond formation between carboxyl groups on ENCC, which endow ENCC with limited water molecule adsorption sites.