Silica fillers were modified by plasma-polymerization coating of 1,3-diaminopropane, allylamine, pyrrole, 1,2-epoxy-5-hexene, allylmercaptan, and allylalcohol using RF plasma (13.56 MHz). Modified fillers were then mixed with biphenyl epoxy resin, phenol novolac (curing agent), and optionally triphenylphosphine (catalyst) to prepare samples for DSC analyses. Some samples were also prepared from uncoated silica fillers and monomers used in plasma polymerization coating, instead of plasma polymer-coated silica fillers. Plasma polymer-coated silica fillers were characterized by FTIR, XPS, and water contact angle measurements. In DSC analyses, all samples with plasma polymer-coated silica fillers showed a large peak and an additional one or two small exothermic peaks when catalyst was added, compared to only one large peak with as-received silica fillers. The large peak could be from epoxy-phenol novolac reaction in the presence of catalyst, whereas small reaction peaks were attributed to the chemical reaction between epoxy resin and functional moieties in the plasma polymer coating, such as amine, OH, and/or SH groups, as evidenced by FTIR and XPS analysis and contact angle measurements. (C) 2003 Wiley Periodicals, Inc.