Assignment of End-Functionalized Polymer by Iminium Ion and Adsorption Enhancement Effect

Recently, it was found that the adsorption efficiency of polymer on the inorganic particle surface had been enhanced by chemical modification of the polymer chain end, without any changes to the other structures. It was also found that the resilience of the mixture of rubber and carbon black could be markedly improved by the modification of the polymer chain end. This suggests that the end-functionalized polymer adsorbed strongly onto carbon black surface and this enhances the dispersion stability of the carbon black. In order to clarify this specific behavior, model compounds with modified chain ends were prepared by directly reacting n-butyl lithium with chemical modifiers (N-alkyl lactam and N-alkylaminobenzophenone) and then quenching by the addition of methanol. It was observed that model compounds had iminium ion group and the adsorption bands in IR spectra of the chemically modified polymer were similar to those of model compounds. We concloud that the iminium ion group at polymer chain end interacts with polar groups on carbon black surface.