Postgrafting of hydrophobic polymer to grafted hydrophilic polymer-grafted on carbon blacks and their dispersibility

摘要

The postgrafting of hydrophobic poly(glycidyl methacrylate-co-methyl methacrylate), P(GMA-co-MMA), to grafted hydrophilic poly(ethyleneimine) on carbon blacks, CB-graft-PEI, and their dispersibility were investigated. The grafting of PEI onto carbon black surface was achieved by the direct condensation of surface carboxyl groups on carbon black with PEI in the presence of N,N'-dicyclohexylcarbodiimide as a condensing agents. The postgrafting of P(GMA-co-MMA) to CB-graft-PEI was successfully proceeded in N,N-dimethylformamide at 80 deg C to give branched polymer-grafted carbon black: total grafting increased to 45-60. CB-graft-PEI gave a stable colloidal dispersion in water, but precipitated in toluene, because of hydrophilic nature of the surface. By postgrafting of P(GMA-co-MMA) to CB-graft-PEI, the carbon black lost its good dispersibility in water, but uniformly and stably dispersed in toluene, because of the hydrophobic nature of postgrafted P(GMA-co-MMA). When P(GMA-co-MMA)-postgrafted CB-graft-PEI was dispersed in water/toluene binary mixture, the water droplets (about 1-3-mm d.) stabilized with P (GMA-co-MMA)-postgrafted CB-graft-PEI was gathered in the intermediate layer. This result indicated that water droplets are surrounded by P(GMA-co-MMA)-postgrafted CB-graft-PEI particles in the same manner as surfactant molecules: grafted PEI and postgrafted P(GMA-co-MMA) chains had good affinity for water and toluene, respectively.