Combined use of methacrylate/epoxy functionalized silanes for tuning of hyperbranched polysiloxane structure

In this work, three hyperbranched polysiloxanes with methacrylate (HSiM), epoxy (HSiG) and methacrylate/epoxy groups (HSiMG) were prepared through the hydrolysis of γ-glycidoxypropyltrimethoxysilane (γ-GPS), γ-methacryloxypropyltrimethoxysilane (γ-MPS) and their binary blends. The results indicated that methacrylate groups could accelerate the condensation reaction, thus producing more branching sites with a branching degree of 0.67 for HSiMG. In addition, the effects of terminal groups on the microstructural and thermal properties of the post-cured hyperbranched polysiloxanes were evaluated. Consequencely, the UV-cured HSiM produced more cracks at a higher temperature due to a tighter crosslinked structure. The thermal-cured HSiG decomposed at a lower temperature. While the dual-curing PHSiMG had a more stable structure and relatively excellent thermal stability, based on sequential free-radical photopolymerization and epoxy anionic polymerization. Thus, this work provides a promising approach for structural design and optimization of the polysiloxane.