Immobilization of flame retardant onto silica nanoparticle surface and properties of epoxy resin filled with the flame retardant‐immobilized silica

To prepare silica nanoparticle having flame retardant activity, the immobilization of flame retardant onto hyperbranched poly(amidoamine) (PAMAM)‐grafted silica was investigated. Grafting of PAMAM onto a silica surface was achieved in a solvent‐free dry‐system using PAMAM dendrimer synthesis methodology. The immobilization of bromine flame retardant, poly(2,2′,6,6′‐tetrabromobisphenol‐A) diglycidyl ether (PTBBA), was successfully achieved by the reaction of terminal amino groups of PAMAM‐grafted silica (Silica‐PAMAM) with epoxy groups of PTBBA. The immobilization of PTBBA was confirmed by FTIR and thermal decomposition GC‐MS. The amount of PTBBA immobilized onto Silica‐PAMAM was determined to be 60 wt %. PTBBA‐immobilized Silica‐PAMAM (Silica‐PAMAM‐PTBBA) was dispersed uniformly in a epoxy resin, and the epoxy resin was cured in the presence of hexamethylenediamine. Flame retardant activity of the epoxy resin filled with Silica‐PAMAM‐PTBBA was estimated by limiting oxygen index (LOI). The LOI of epoxy resin filled with Silica‐PAMAM‐PTBBA was higher than that filled with untreated silica and free PTBBA. It was confirmed that the flame retardant activity of epoxy resin was improved by the addition of the Silica‐PAMAM‐PTBBA. The elimination of PTBBA from the epoxy resin filled with Silica‐PAMAM‐PTBBA into boiling water was hardly observed by immobilization of PTBBA onto silica surface. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6145–6152, 2009