Nanoporous silicone resins and silicone resin films having low dielectric constants and a method for preparing such nanoporous silicone resins. The silicone resin comprises the reaction product of a mixture comprising
(A) 15-70 mol % of a tetraalkoxysilane described by formula
where each R
is an independently selected alkyl group comprising 1 to about 6 carbon atoms,
(B) 12 to 60 mol % of a hydrosilane described by formula
where each X is an independently selected hydrolyzable substituent,
(C) 15 to 70 mole percent of an organotrialkoxysilane described by formula
is a hydrocarbon group comprising about 8 to 24 carbon atoms or a substituted hydrocarbon group comprising a hydrocarbon chain having about 8 to 24 carbon atoms and each R
is an independently selected alkyl group comprising 1 to about 6 carbon atoms; in the presence of
(E) hydrolysis catalyst, and
(F) organic solvent for the reaction product.
The silicone resin is cured and heated in an inert atmosphere at a temperature sufficient to effect thermolysis of carbon-carbon bonds of the R
groups thereby forming a nanoporous silicone resin.