Environment-friendly synthesis and performance of a novel hyperbranched epoxy resin with a silicone skeleton

Hyperbranched epoxy resins have attracted increasing attention for their excellent comprehensive performance in toughening and reinforcing the diglycidyl ether of bisphenol-A (DGEBA). However, the tedious synthetic procedure, high cost, and the use of large amounts of organic solvents have hampered their industrial application. This paper presents an environment-friendly method to synthesize a novel hyperbranched epoxy resin with a silicone skeleton (HERSS) through a hydrosilylation reaction catalyzed by a heterogeneous halloysite-supported platinum catalyst. The reaction involves only one solvent and affords a high yield (>90%). The chemical structure, molecular weight, and degree of branching of the HERSS were characterized by FT-IR, GPC and NMR. The resulting HERSS was used to modify a DGEBA based epoxy resin and showed excellent performance. With the incorporation of 9 wt% HERSS, the impact, flexural and tensile strength of DGEBA are increased by about 92.5%, 36.0% and 88.6%, respectively. The toughening and reinforcing mechanism was attributed to the "sea-island" structure of the cure composite, as shown by the SEM micrographs of the fractured surfaces. An initial thermal decomposition temperature of about 380.0 °C of the cured HERSS/methyl nadic anhydride resin also indicates promising applications with regard to high-temperature-resistance.