Low dielectric constant nanoporous silica/PMMA nanocomposites with improved thermal and mechanical properties

Periodic mesoporous organosilicas (PMOs) with 3D cubic framework and worm-hole framework, inorganic mesoporous silica with 3D cubic framework and organic-inorganic nanometer sized hollow spheres were synthesized with different molar ratios of 1,2-bis(triethoxysilyl)ethane (BTESE) and tetraethylorthosilicate (TEOS) as silica precursors, and were used to prepare nanoporous silica/poly(methyl methacrylate) (PMMA) nanocomposites with lower dielectric constant, higher thermal and mechanical properties. The micro-structures of above nanoporous silicas (NPSs) were retained in NPS/PMMA nanocomposites with 2 wt% loading of NPS. NPSs provided composites with lower dielectric constant (κ≈2.73) in comparison to pure PMMA (κ=2.91) due to introduction of voids. All the composites exhibited improved mechanical properties, glass transmission temperature (Tg) and thermal stability in comparison to PMMA. The tensile strength, tensile modulus, flexural strength and flexural modulus of the composites increased with the molar percentage of BTESE increased from 0% to 100%, and only slight compromised elongation at break and impact strength were observed.