375
α,ω-diallyl-PEG and α,ω-diallyl-polyisobutylene segments and vinyl-end PDMS
with D
H 5 , and hydrolysis of the Si-H groups to Si-OH groups and consecutive polycondensation to PD 5 domains (Kurian and Kennedy 2002a, b). These membranes
were suitable for immunoisolation, exhibiting excellent mechanical properties
(TS > 5 MPa and E b = 500%) (Kurian et al. 2003; Kennedy et al. 2004). Its additional reinforcement was achieved with Q 8 M
H 8 (Isayeva and Kennedy 2004).
The crosslinking of D
H 4 with divinylbenzene gave hybrid coating materials with
very good termal and mechanical properties (Pinho et al. 2004). Phenylsilsesquioxane
resin containing vinyl groups were crosslinked with H-siloxane oligomers: linear
M
H 2 D and star Si(OSiMe 2 H) 4 (Li et al. 2001).
New polysiloxanes crosslinked with photoinitiators were prepared by the hydrosilylation reactions of PMHS and PDMS-co-PMHS of the statistical structures
(MD x D
H 100-x M, x = 0 or 50) with 6,6,6-tris-(trimethylsilyl)-hex-1-ene and allylglicydyl ether, which had high thermal stability (Kowalewska and Stańczyk 2003).
PMHS and PDMS-b-PMHS of random structures (MD x D
H 100-x M, x = 30, 50, 85) or
block structures (M(D 2 D
H
) 7 D 2 M and M(D 2 D
H 2 ) 11 D 2 M)) were modified by hydrosilylation with vinyl-carbosilanes having sterically hindred groups (CH 2 =
CHRC(SiMe 2 R’) 3 , R = -CH 2 , −(CH 2 ) 3 or -SiMe 2 ; R’ = −Me or -Ph). The thermal
resistance of polycarbosiloxanes obtained increased due to the decrease of flexibility of the siloxane chains and a free energy change (Kowalewska et al. 2009).
A new material ((C 5 H 4 Sc) 8 Si 8 O 12 ) was obtained by Sun et al. (2007) from reaction of T
H 8 with a scandium-cyclopentadienyl derivative, which is very useful for
hydrogen storage. Methacrylate and epoxy-functionalized silsesquioxane nanocomposites based on Q 8 M
H 8 cores were used as dental materials (Soh et al. 2007).
Self-hydrosilylation of Si-H and Si-Vi functional macrocyclic siloxanes: 12- or
24-membered (dimethylsiloxy)vinylsilsesquioxanes with the formula: (M
H
ViSiO) n
[n = 6 (A), 12 (B)] (Scheme 14.12) gave highly porous crosslinked poly(silsesquio
xanecarbosilanes) (Han and Zheng 2008).
The inorganic-organic hybrid glasses synthesized by the hydrosilylation of D
Vi 4
with (MeHSiO) 4 and catalyzed by Pt were thermally stable up to 400 °C (Michalczyk
et al. 1993). The preceramic polycarbosiloxanes were also prepared by the hydrosilylation of D
Vi 4 with linear dihydrosiloxanes (M
H 2 D n , n = 0–2). Their pyrolysis at
1000 °C gave 86–89% ceramic yields (Nyczyk et al. 2011).
14.6.5 Modification of the Properties of Polyolefins
and Polydienes by the Hydrosilylation Method
High MW copolymers were obtained from 1-(9-decenyl)-3,5,7,9,11,13,15- heptaeth
ylpentacyclo[9.5.1.13,9.15,15.17,13]octasilsesquioxane with ethylene or propylene
in the presence of metallocene-alumoxane catalysts. They contained up to 25 wt.%
(1.2 mol.%) of pendant silsesquioxane units and showed lower T m values (by 18 K)
and better thermostability in air atmosphere compared to poly(ethylene) (PE)
(Tsuchida et al. 1997). The hydrosilylation of end double bonds is an important
14 Hydrosilyl-Functional Polysiloxanes: Synthesis Reactions and Applications
α,ω-diallyl-PEG and α,ω-diallyl-polyisobutylene segments and vinyl-end PDMS
with D
H 5 , and hydrolysis of the Si-H groups to Si-OH groups and consecutive polycondensation to PD 5 domains (Kurian and Kennedy 2002a, b). These membranes
were suitable for immunoisolation, exhibiting excellent mechanical properties
(TS > 5 MPa and E b = 500%) (Kurian et al. 2003; Kennedy et al. 2004). Its additional reinforcement was achieved with Q 8 M
H 8 (Isayeva and Kennedy 2004).
The crosslinking of D
H 4 with divinylbenzene gave hybrid coating materials with
very good termal and mechanical properties (Pinho et al. 2004). Phenylsilsesquioxane
resin containing vinyl groups were crosslinked with H-siloxane oligomers: linear
M
H 2 D and star Si(OSiMe 2 H) 4 (Li et al. 2001).
New polysiloxanes crosslinked with photoinitiators were prepared by the hydrosilylation reactions of PMHS and PDMS-co-PMHS of the statistical structures
(MD x D
H 100-x M, x = 0 or 50) with 6,6,6-tris-(trimethylsilyl)-hex-1-ene and allylglicydyl ether, which had high thermal stability (Kowalewska and Stańczyk 2003).
PMHS and PDMS-b-PMHS of random structures (MD x D
H 100-x M, x = 30, 50, 85) or
block structures (M(D 2 D
H
) 7 D 2 M and M(D 2 D
H 2 ) 11 D 2 M)) were modified by hydrosilylation with vinyl-carbosilanes having sterically hindred groups (CH 2 =
CHRC(SiMe 2 R’) 3 , R = -CH 2 , −(CH 2 ) 3 or -SiMe 2 ; R’ = −Me or -Ph). The thermal
resistance of polycarbosiloxanes obtained increased due to the decrease of flexibility of the siloxane chains and a free energy change (Kowalewska et al. 2009).
A new material ((C 5 H 4 Sc) 8 Si 8 O 12 ) was obtained by Sun et al. (2007) from reaction of T
H 8 with a scandium-cyclopentadienyl derivative, which is very useful for
hydrogen storage. Methacrylate and epoxy-functionalized silsesquioxane nanocomposites based on Q 8 M
H 8 cores were used as dental materials (Soh et al. 2007).
Self-hydrosilylation of Si-H and Si-Vi functional macrocyclic siloxanes: 12- or
24-membered (dimethylsiloxy)vinylsilsesquioxanes with the formula: (M
H
ViSiO) n
[n = 6 (A), 12 (B)] (Scheme 14.12) gave highly porous crosslinked poly(silsesquio
xanecarbosilanes) (Han and Zheng 2008).
The inorganic-organic hybrid glasses synthesized by the hydrosilylation of D
Vi 4
with (MeHSiO) 4 and catalyzed by Pt were thermally stable up to 400 °C (Michalczyk
et al. 1993). The preceramic polycarbosiloxanes were also prepared by the hydrosilylation of D
Vi 4 with linear dihydrosiloxanes (M
H 2 D n , n = 0–2). Their pyrolysis at
1000 °C gave 86–89% ceramic yields (Nyczyk et al. 2011).
14.6.5 Modification of the Properties of Polyolefins
and Polydienes by the Hydrosilylation Method
High MW copolymers were obtained from 1-(9-decenyl)-3,5,7,9,11,13,15- heptaeth
ylpentacyclo[9.5.1.13,9.15,15.17,13]octasilsesquioxane with ethylene or propylene
in the presence of metallocene-alumoxane catalysts. They contained up to 25 wt.%
(1.2 mol.%) of pendant silsesquioxane units and showed lower T m values (by 18 K)
and better thermostability in air atmosphere compared to poly(ethylene) (PE)
(Tsuchida et al. 1997). The hydrosilylation of end double bonds is an important
14 Hydrosilyl-Functional Polysiloxanes: Synthesis Reactions and Applications