초록 |
Processible polysilsesquioxanes (PSSQs), (RSiO1.5)x, were synthesized via terpolymerization of methyltrifunctional monomer, methyltrimethoxysilane (MTMS) with bridged hexafunctional comonomer, 1,2-bistrimethoxysilylethan (BTMSE) and difunctional comonomer, dimethoxydimethylsilane (DMDMS) to investigate the optimum molecular structure and the applicability of nanoporous materials for low dielectric constant (k) applications. The results showed that bridged comonomer, BTMSE, plays a key role as it significantly improves the modulus and the hardness over those of poly(methylsilsesquioxane) homopolymer. In addition, the crack resistance is also substantially enhanced. Moreover, nanoporous films were produced from hybrid structures of PSSQ precursor and thermally labile organic pore generators. All the final films were defect-free and produced high-optical quality after final curing to 450oC, with porosities close to 50 % and pore sizes smaller than 10 nm. The dielectric constant was decreased down to 1.5, a minimum value reported so far for mechanically tough nanoporous films.
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