PAAm-g-CB/Al_2O_3凝胶杂合材料的制备及负蒸气系数效应研究

Preparation of Polyacrylamide Grafted Carbon Black/Alumina(PAAm-g-CB/Al_2O_3) Gel Hybrid Material and Its Negative Vapor Coefficient Effect

利用自由基反应机理 ,以过氧化苯甲酰 (BPO)为引发剂 ,在炭黑表面引入 CH2 OH或 C(CH3) 2 OH ;然后再以硝酸铈铵 /CB -CH2 OH或硝酸铈铵 /CB C(CH3) 2 OH组成氧化还原引发体系 ,在CB表面接枝上聚丙烯酰胺 (PAAm g CB) ;在PAAm g CB存在下 ,进行AIP(异丙醇铝 )的溶胶 凝胶化反应 ,制得了一种新颖的具有智能响应性的PAAm g CB/Al2 O3凝胶杂合材料。研究了其气敏性能和湿敏性能。结果发现 ,该杂合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。其响应性能与杂合体间氢键作用密切相关 ,并受接枝率大小的影响 ;结合IR、DTA、TGA等分析方法推断了杂合材料分子结构模型。

The preparation and its gas or vapor sensitivity of a novel PAAm g CB/Al 2O 3 gel hybrid material with intellectual responsiveness 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 ceric ammonium nitrate and carbon black having 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 show that the electric resistance of the hybrid material rapidly decreased in good solvent vapors for grafted polymer on carbon black, presenting a negative vapor coefficient phenomenon (NVC),but not in non good solvent vapors. The responsiveness of the hybrid material to good solvent vapors is related to the hydrogen bond between carbonyl groups of the grafted polymer and the residual hydroxyl groups in the alumina gel, and effected by graft percentage; the molecular structure model of the hybrid material was proposed combining IR, DTA, TGA etc.