357
cyclopentyl and cyclohexyl-substituted polysiloxanes (Chakraborty and
Soucek 2008) (Scheme 14.5).
Carboxyl functional POSS derivatives have also been prepared by addition of
4- allyloxy benzoil acid into T
H
8 (Yang et al. 2011). Moran et al. (1993) and Casado
et al. (1995) reported the addition of vinyl ferrocene into D
H
4 and Q 8 M
H
8 . POSScarborane resins were prepared by the hydrosilylation of vinyl-terminated carborane
monomer with Q 8 M
H
8 , and cured with the catalyst Pt 2 [(ViSiMe 2 ) 2 O] 3 . The extra reinforced POSS-carborane network with additional Si-O-Si crosslinks have also been
obtained using an excess of Q 8 M
H
8 , followed by the oxidation, hydrolysis of Si-H
bonds and condensation reactions with intermediate Si-OH groups, in the presence
of the catalyst Pt 2 [(ViSiMe 2 ) 2 O] 3 and Et 3 N/H 2 O cocatalysts (Kolel-Veeti et al. 2008).
The NaHBEt 3 -catalyzed hydrosilylation of allyl glycidyl ether, styrenes and
vinylsilanes with aromatic hydrosilanes has been performed according to the highly
regioselective anionic Markovnikov mechanism (Zaranek et al. 2017). The first
example of NaHBEt 3 -catalyzed dehydrocondensation reaction between C-H and
Si-H bonds was reported by Skrodzki et al. (2018b). The aromatic and aliphatic
alkynes reacted with aromatic hydrosilanes and hydrosiloxanes in a highly selective
manner, without formation of hydrosilylation side-products of the end alkyne
group (Scheme 14.6) (Skrodzki et al. 2018b).
14.5.2.1 Synthesis of Hybrid Silicone-Based Materials from PMHS
Many chemical modifications of unsaturated organic polymers have been very often
realized with an application of Si-H functional substrates via sol-gel or the hydrosilylation processes. The branched PMHS-based coatings have been prepared at RT
by sol-gel hydrolytic polycondensation of diethoxymethylsilane (HSiMe(OEt) 2 )/
TES mixtures:
xHSiMe OEt
x HSi OEt
x H O
HSiMe OEt
x
( ) + ( ) ( ) + ( )
→
→
( )
2
3
2
2 2
1
3
2
–
–
/
/
H HSiO
x EtOH
x
3 2 1
3
/
–
–
[
]
+ ( )
( )
(14.8)
A dip-coating method was applied by Thami et al. (2007) onto a freshly activated
silicon wafer. Following Thami et al. (2007) the crosslinking density of PMHS thin
Scheme 14.6 The
proposed mechanism of
dehydrocondensation of
hydrosilanes with alkynes.
Adapted with permission
from Skrodzki
et al. (2018b)
14 Hydrosilyl-Functional Polysiloxanes: Synthesis Reactions and Applications
cyclopentyl and cyclohexyl-substituted polysiloxanes (Chakraborty and
Soucek 2008) (Scheme 14.5).
Carboxyl functional POSS derivatives have also been prepared by addition of
4- allyloxy benzoil acid into T
H
8 (Yang et al. 2011). Moran et al. (1993) and Casado
et al. (1995) reported the addition of vinyl ferrocene into D
H
4 and Q 8 M
H
8 . POSScarborane resins were prepared by the hydrosilylation of vinyl-terminated carborane
monomer with Q 8 M
H
8 , and cured with the catalyst Pt 2 [(ViSiMe 2 ) 2 O] 3 . The extra reinforced POSS-carborane network with additional Si-O-Si crosslinks have also been
obtained using an excess of Q 8 M
H
8 , followed by the oxidation, hydrolysis of Si-H
bonds and condensation reactions with intermediate Si-OH groups, in the presence
of the catalyst Pt 2 [(ViSiMe 2 ) 2 O] 3 and Et 3 N/H 2 O cocatalysts (Kolel-Veeti et al. 2008).
The NaHBEt 3 -catalyzed hydrosilylation of allyl glycidyl ether, styrenes and
vinylsilanes with aromatic hydrosilanes has been performed according to the highly
regioselective anionic Markovnikov mechanism (Zaranek et al. 2017). The first
example of NaHBEt 3 -catalyzed dehydrocondensation reaction between C-H and
Si-H bonds was reported by Skrodzki et al. (2018b). The aromatic and aliphatic
alkynes reacted with aromatic hydrosilanes and hydrosiloxanes in a highly selective
manner, without formation of hydrosilylation side-products of the end alkyne
group (Scheme 14.6) (Skrodzki et al. 2018b).
14.5.2.1 Synthesis of Hybrid Silicone-Based Materials from PMHS
Many chemical modifications of unsaturated organic polymers have been very often
realized with an application of Si-H functional substrates via sol-gel or the hydrosilylation processes. The branched PMHS-based coatings have been prepared at RT
by sol-gel hydrolytic polycondensation of diethoxymethylsilane (HSiMe(OEt) 2 )/
TES mixtures:
xHSiMe OEt
x HSi OEt
x H O
HSiMe OEt
x
( ) + ( ) ( ) + ( )
→
→
( )
2
3
2
2 2
1
3
2
–
–
/
/
H HSiO
x EtOH
x
3 2 1
3
/
–
–
[
]
+ ( )
( )
(14.8)
A dip-coating method was applied by Thami et al. (2007) onto a freshly activated
silicon wafer. Following Thami et al. (2007) the crosslinking density of PMHS thin
Scheme 14.6 The
proposed mechanism of
dehydrocondensation of
hydrosilanes with alkynes.
Adapted with permission
from Skrodzki
et al. (2018b)
14 Hydrosilyl-Functional Polysiloxanes: Synthesis Reactions and Applications