Synthesis, morphology and properties of polydimethylsiloxane-modified allylated novolac/4,4′-bismaleimidodiphenylmethane

Polydimethylsiloxane was incorporated into the backbone of allylated novolac (AN) to improve the toughness of allylated novolac/4,4′-bismaleimidodiphenylmethane(AN/BDM). Polydimethylsiloxane–modified allylated novolac (PDMS–AN) was synthesized via the hydrosilylation reaction between the terminal Si–H groups of α,ω-hydrogen functional dimethylsiloxane oligomer (PDMS) and the allyl groups of allylated novolac resin (AN). The blend of PDMS–AN and 4,4′-bismaleimidodiphenylmethane (BDM) could undergo co-cure reaction at elevated temperatures, and the co-cure system was denoted PDMS–AN/BDM. PDMS–AN was characterized by Fourier transfer infrared (FTIR) spectroscopy, 1H and 29Si nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The curing behavior of PDMS–AN/BDM was evaluated by differential scanning calorimetry (DSC). The morphology of the cured resins was examined by scanning electron microscope (SEM) and dynamic mechanical analysis (DMA). The effects of the content and number-average molecular weight of the incorporated PDMS on the mechanical and thermal properties of PDMS–AN/BDM were investigated. The results indicated that the incorporation of PDMS could improve the impact toughness of AN/BDM.