聚丙烯酰胺在炭黑粒子表面的功能修饰及其负蒸气系数效应

Carbon black surface functionalization by polyacrylamide and its negative vapor coefficient effect

以硝酸铈铵/CB-CH2OH或硝酸铈铵/CB-C(CH3)2OH为氧化还原引发体系,在炭黑(CB)表面接枝了聚丙烯酰胺(PAAm-g-CB);通过PAAm-g-CB存在下的异丙醇铝(AIP)溶胶-凝胶化反应,制得一种新的具有智能响应性的PAAm-g-CB/Al2O3凝胶杂化材料,研究了其气敏和湿敏性能.结果表明,该杂化材料在其良溶剂蒸气中电阻急剧下降,呈现负蒸气系数现象(NVC);而在不良溶剂蒸气中电阻几乎不发生变化.其响应性能与杂化体间氢键作用密切相关,并受接枝率大小的影响.

The preparation and vapor sensitivity of a novel PAAm-g-CB/Al2O3 gel hybrid material with smart responsiveness prepared by the sol-gel process of isopropoxide （AIP） in the presence of PAAm-g- CB were investigated. The polyacrylamide grafted carbon black was synthesized by a redox system of ammonium cerium （IV） nitrate in the presence of carbon black containing alcoholic hydroxyl groups. The introduction of alcoholic hydroxyl groups onto carbon black surface was achieved by the reaction of carbon black with alcoholic hydroxyl radicals formed by the reaction of alcohols with benzoyl peroxide. The results showed that the electric resistance of the hybrid material rapidly decreased in good solvent vapors for the hybrid material, presenting a negative vapor coefficient phenomenon （NVC）. However, the same effect was not observed in poor solvent vapors. The responsiveness is related to the graft percentage and the hydrogen bond between carbonyl groups of the grafted polymer and the residual hydroxyl groups in the alumina gel.