342
toluene, were cured into thin photoresist films with excellent hardness, high thermal
resistance and optical transparency (Harkness et al. 1997; 1999).
14.2.5 Densely Crosslinked Hybrid Materials Based on PMHS
Hydrophobic PHS xerogels, stable in air up to 260 °C, were prepared by the hydrolytic polycondensation of TES, in acidic medium (Siliniakova et al. 1964, 1965).
They reduced metal ions to free metals (e.g. Ag, Hg, Pd, Pt) (Budkevitsch et al.
1966). Belot et al. (1991) synthesized hydrophobic hydrosilsesquioxane gels T
H 8
(thermally stable up to ≥300 °C) by the hydrolytic polycondensation of TES or
HSiCl 3 . The hydrolytic condensation of TES and MDES with MTES or TEOS gave
hybrid silica xerogels which were good precursors for silicon oxycarbide (SiOC)
glasses (Babonneau et al. 1992, Babonneau and Maquet 2000; Soraru et al. 1995a,
b; Gualandris et al. 1998). Similarly, from mixtures of TES and MDES, changing
T
H
/D
H
ratio, was obtained the homogeneous elastic gel, where the crosslinked networks were formed by MeHSiO 2/2 units, linked by randomly dispersed HSiO 3/2 units
(Schaudel et al. 1997). Thin highly hydrophobic and very stable nano- and micrometric films of the crosslinked Si-H functional PMHS were grafted onto silica via
a sol-gel process of a mixture of HMeSi(OEt) 2 and TES (Thami et al. 2007). The
hydrolytic polycondensation of linear PMHS with TEOS catalyzed by NaOH, in the
absence of surfactants gave superhydrophobic hybrid xerogels (Yang et al. 2006).
Highly branched poly(pentamethylcyclopentasiloxane) consisting of many tenmembered siloxane rings, linked through Si-O-Si bonds, have been prepared by the
hydrolysis of the Si-H groups of 1,3,5,7,9-pentamethylpentacyclosiloxane
((HMeSiO) 5 ), in the presence of Karstedt’s catalyst (Pt 2 [(ViSiMe 2 ) 2 O] 3 ), followed
by the dehydrocondensation between Si-H and Si-OH groups, at a temperature of
100 °C. This unusual hybrid product was a stiff and brittle solid, insoluble in common solvents, but it had an extremely low glass transition temperature (T g = −152 °C)
without a melting transition, and absorbing up to 3% water, and showing oxygen
permeability and high thermostability up to 700 °C (Kurian et al. 2002).
14.2.6 Synthesis of Dendritic Poly(siloxysilane)s Containing
H-Silane Functionalities
Siloxane-carbosilane glasses with thermal stability up to 400 °C under argon atmosphere, were prepared by polyaddition of D
H 4 into 1,3,5,7-tetramethyl-1,3,5,7tetravinylcycle tetrasiloxane ((MeViSiO) 4 , D
Vi 4 ) (Michalczyk et al. 1993). Many
hyperbranched poly(siloxysilane)s (e.g. poly(carbosiloxane)s (PSCS)) with Si-H
and olefin functionalities have been obtained via hydrosilylation reactions of AB x
type monomers (x = 2–6). They contained Si-H groups, unsaturated double bonds,
Si-O-Si and C-Si bonds (Mathias and Carothers 1991; Flipsen et al. 1997; Miravet
J. J. Chruściel
toluene, were cured into thin photoresist films with excellent hardness, high thermal
resistance and optical transparency (Harkness et al. 1997; 1999).
14.2.5 Densely Crosslinked Hybrid Materials Based on PMHS
Hydrophobic PHS xerogels, stable in air up to 260 °C, were prepared by the hydrolytic polycondensation of TES, in acidic medium (Siliniakova et al. 1964, 1965).
They reduced metal ions to free metals (e.g. Ag, Hg, Pd, Pt) (Budkevitsch et al.
1966). Belot et al. (1991) synthesized hydrophobic hydrosilsesquioxane gels T
H 8
(thermally stable up to ≥300 °C) by the hydrolytic polycondensation of TES or
HSiCl 3 . The hydrolytic condensation of TES and MDES with MTES or TEOS gave
hybrid silica xerogels which were good precursors for silicon oxycarbide (SiOC)
glasses (Babonneau et al. 1992, Babonneau and Maquet 2000; Soraru et al. 1995a,
b; Gualandris et al. 1998). Similarly, from mixtures of TES and MDES, changing
T
H
/D
H
ratio, was obtained the homogeneous elastic gel, where the crosslinked networks were formed by MeHSiO 2/2 units, linked by randomly dispersed HSiO 3/2 units
(Schaudel et al. 1997). Thin highly hydrophobic and very stable nano- and micrometric films of the crosslinked Si-H functional PMHS were grafted onto silica via
a sol-gel process of a mixture of HMeSi(OEt) 2 and TES (Thami et al. 2007). The
hydrolytic polycondensation of linear PMHS with TEOS catalyzed by NaOH, in the
absence of surfactants gave superhydrophobic hybrid xerogels (Yang et al. 2006).
Highly branched poly(pentamethylcyclopentasiloxane) consisting of many tenmembered siloxane rings, linked through Si-O-Si bonds, have been prepared by the
hydrolysis of the Si-H groups of 1,3,5,7,9-pentamethylpentacyclosiloxane
((HMeSiO) 5 ), in the presence of Karstedt’s catalyst (Pt 2 [(ViSiMe 2 ) 2 O] 3 ), followed
by the dehydrocondensation between Si-H and Si-OH groups, at a temperature of
100 °C. This unusual hybrid product was a stiff and brittle solid, insoluble in common solvents, but it had an extremely low glass transition temperature (T g = −152 °C)
without a melting transition, and absorbing up to 3% water, and showing oxygen
permeability and high thermostability up to 700 °C (Kurian et al. 2002).
14.2.6 Synthesis of Dendritic Poly(siloxysilane)s Containing
H-Silane Functionalities
Siloxane-carbosilane glasses with thermal stability up to 400 °C under argon atmosphere, were prepared by polyaddition of D
H 4 into 1,3,5,7-tetramethyl-1,3,5,7tetravinylcycle tetrasiloxane ((MeViSiO) 4 , D
Vi 4 ) (Michalczyk et al. 1993). Many
hyperbranched poly(siloxysilane)s (e.g. poly(carbosiloxane)s (PSCS)) with Si-H
and olefin functionalities have been obtained via hydrosilylation reactions of AB x
type monomers (x = 2–6). They contained Si-H groups, unsaturated double bonds,
Si-O-Si and C-Si bonds (Mathias and Carothers 1991; Flipsen et al. 1997; Miravet
J. J. Chruściel