To modify carbon black surface, the surface grafting of hyperbranched poly(amidoamine) onto the surface by using dendrimer synthesis methodology was investigated. Carbon black having amino groups (initiator sites) was prepared by the reduction of surface nitro groups introduced by nitration of aromatic rings. It was found that hyperbranched poly(amidoamine) was propagated from carbon black surface by repeating two processes: (1) Michael addition of methyl acrylate (MA) to surface amino groups and (2) amidation of the resulting esters with ethylenediamine: the percentage of poly(amidoamine) grafting reached to 96.2% after 10th‐generation. The grafting of hyperbranched poly(amidoamine) onto polystyrene‐bead as a model compound of carbon black was also achieved by the above procedures. However, the theoretical propagation of poly(amidoamine) dendrimer was not achieved, because of steric hindrance of grafted polymer. Hyperbranched poly(amidoamine)‐grafted carbon black gave a stable dispersion in a good solvent for poly(amidoamine). Copyright © 2001 John Wiley & Sons, Ltd.

Hyperbranched polyamidoamine-grafted silica was prepared according to dendrimer synthesis methodology. The modified silica was dispersed uniformly in epoxy resin, and the curing of epoxy resin proceeded successfully by heating in the presence of the modified silica; the gel fraction of the epoxy resin cured by the hyperbranched polyamidoamine-grafted silica (grafting ϭ 80.2%) reached 77% at 170°C after 48 h. The gel fraction increased with increasing terminal amino group content of the hyperbranched polyamidoamine-grafted silica. In addition, the curing ability of the silica increased by complexation of the terminal amino groups of the grafted polyamidoamine with boron trifluoride. The modulus of elasticity of the curing materials obtained using the modified silica as a curing agent was lower than that using conventional a curing agent such as ethylenediamine in the presence of untreated silica. On the other hand, the heat resistance of the curing product using the modified silica was superior to that using ethylenediamine, but no difference in glass-transition temperature was observed. It is expected that hyperbranched polyamidoamine grafted-silica is incorporated uniformly with chemical bonds in the matrix of the epoxy resin.

Scale-up Synthesis of Hyperbranched Poly(amidoamine)-grafted Silica / 145 a Amino group content of initiator site, 0.33 mmol/g. b R = experimental value/calculated value.

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