Preparation of IPN-type carbon black nano-composite and its responsibility agains solvent vapor

为了制备一种新型的气体传感器，研究了互穿网络(IPN)型纳米复合材料的电阻响应特性。以N，N‘-二环己基碳二亚胺为缩合剂，将结晶聚合物的端羟基与表面的羧基直接缩合，成功地在炭黑表面接枝了结晶聚合物，如聚乙烯(PB)、聚己内酯(PCL)、聚乙二醇(PEG)和聚己二酸乙二醇酯(PEA)。将聚合物接枝的炭黑与结晶聚合物混合，制备了均匀的电阻；在…存在下，用阳离子开环聚合法制备了聚乙烯接枝炭黑与聚己内酯的互穿网络型纳米复合材料更多的是接枝有黑点的PB-炭黑。尽管复合材料在干正己烷中几乎没有观察到电阻的变化，但在含有接枝聚合物良好溶剂的正己烷中，由结晶聚合物接枝炭黑制备的纳米复合材料的电阻显著增加。例如，在含有氯仿、四氢呋喃和乙醇的己烷中，PCL接枝炭黑的复合材料的电阻增大，当复合材料在干燥的己烷中转移时，复合材料的电阻恢复到初始电阻，发现复合材料的电阻对数与氯仿在己烷中的浓度成线性关系。这表明该复合材料还可以作为一种新型的溶质传感器和密度计，这是由于接枝聚合物的良好溶剂对溶质的吸附改变了炭黑颗粒之间的晶格结构，从而使颗粒之间的间隙发生了微小的变化。较少

To prepare a novel gas sensor against various solvent vapor, the responsibility of electric resistance of inter penetrating network (IPN)-type nano-composite was investigated. In addition, the responsibility of electric resistance of composite from crystalline polymer-grafted carbon black against solute in hexane was also examined.Crystalline polymers, such as polyethylene (PB), poly(epsilon-caprolactone) (PCL), poly(ethylene glycol) (PEG), and poly(ethylene adipate) (PEA) were successfully grafted onto carbon black surface by direct condensation of terminal hydroxyl groups of these polymers with carboxyl groups on the sufface using N,N'-dicyclohexyl-carbodiimide as a condensing agent. A uniform resistor was readily pre-pared by mixing the the polymer-grafted carbon black with crystalline polymer.The preparation of inter penetrating network (IPN)-type nano-composite of PE-grafted carbon black with PCL was achieved by cationic ring-opening polymerization of CL in the presence of crossli … More nked PB-grafted carbon black. No responsibility of the composite against solvent vapor, however, was observed because of crosslink-ing of matrix polymer.Although the change of electric resistance of the composite hardly observed in dry hexane, the electric resistance of a nano-composite prepared from crystalline polymer-grafted carbon black drastically increased in hexane containing good solvent of grafted polymer. For example, the electric resistance of composite from PCL-grafted carbon black increased in hexane containing chloroform, tetrahydrofuran, and alcohol, and returned to initial resistance when the composite was transferred in dry hexane.It was found that the logarithm of electric resistance of the composite is linearly proportional to chloroform concentration in hexane. This indicates that the composite can be also applied as a novel solute sensor and a densitometer.This is due to a slight change of gaps between carbon black particles by the change of crystalline structure based on the absorption of solute of a good solvent of grafted polymer. Less