334
PHS and poly(methylhydrosiloxane)s (PMHS) are colourless liquids. A chemical structure of linear PMHS is described by a general formula:
RMe SiO Me SiO
MeHSiO SiMe R
m
n
2
2
2
(
) (
)
where Me = CH 3 ; R = CH 3 (most often) or another organic group or H,
m ≥ 0, n ≥ 1.
The PMHS structures are often expressed by abbreviated formulas, e.g.
MD m D
H n M, in which appropriate molecular units are abbreviated as follows:
D = 0.5 O-Si-O 0.5
Me
Me
D H = 0.5 O-Si-O 0.5
H
Me
M = 0.5 O-Si-Me
Me
Me
Me2SiO (D)
M e(H)SiO (D
H
)
M e3SiO0.5 (M)
Cyclic (Stock and Somieski 1919; Wilcock and Hurt 1951; Campbell-Ferguson
1965; Glidewell et al. 1970; Seyferth et al. 1983) and linear PHS of the structure
Me 3 SiO(H 2 SiO) n SiMe 3 with a kinematic viscosity 10 cSt (Seyferth et al. 1983) have
been synthesized by a hydrolytic polycondensation of dichlorosilane (H 2 SiCl 2 ) and
trimethylchlorosilane (Me 3 SiCl, TMCS) in a cold, concentrated hydrochloric acid
(Wilcock 1949). Volatile cyclosiloxanes (H 2 SiO) n (n = 4–23) have been distilled off
from hydrolysis products of H 2 SiCl 2 (Seyferth et al. 1983). PMHS of the structure
Me 3 SiO[HSi(OSiMe 3 )O] n SiMe 3 have been prepared by the hydrolysis of trichlorosilane (HSiCl 3 ) with 80% sulfuric acid (H 2 SO 4 ). As a side product, octahydrosiloctasequioxane (T
H 8 , (HSiO 1.5 ) 8 ; H 8 Si 8 O 12 ) is obtained (Müller et al. 1959).
14.2 Synthesis of PHS and PMHS
Many types of polymerization methods have been useful for the synthesis of PHS
and PMHS: dehydrocondensation, ionic polymerization, polyaddition, polycondensation, redistribution (rearrangement, equilibration polymerization), dehydrocarbocondensation, thermal and catalytic depolymerization. The Si-H bond is quite stable
under acidic conditions and very unstable in the presence of oxygen, bases and
moisture (Lee 1966).
14.2.1 Synthesis of PMHS With Linear and Ring Structures
Linear and monocyclic PMHS are prepared by the following methods (White 1995;
Kricheldorf 1996; Chruściel 1999a; Brook 2000; Rościszewski and Zielecka 2002):
J. J. Chruściel
PHS and poly(methylhydrosiloxane)s (PMHS) are colourless liquids. A chemical structure of linear PMHS is described by a general formula:
RMe SiO Me SiO
MeHSiO SiMe R
m
n
2
2
2
(
) (
)
where Me = CH 3 ; R = CH 3 (most often) or another organic group or H,
m ≥ 0, n ≥ 1.
The PMHS structures are often expressed by abbreviated formulas, e.g.
MD m D
H n M, in which appropriate molecular units are abbreviated as follows:
D = 0.5 O-Si-O 0.5
Me
Me
D H = 0.5 O-Si-O 0.5
H
Me
M = 0.5 O-Si-Me
Me
Me
Me2SiO (D)
M e(H)SiO (D
H
)
M e3SiO0.5 (M)
Cyclic (Stock and Somieski 1919; Wilcock and Hurt 1951; Campbell-Ferguson
1965; Glidewell et al. 1970; Seyferth et al. 1983) and linear PHS of the structure
Me 3 SiO(H 2 SiO) n SiMe 3 with a kinematic viscosity 10 cSt (Seyferth et al. 1983) have
been synthesized by a hydrolytic polycondensation of dichlorosilane (H 2 SiCl 2 ) and
trimethylchlorosilane (Me 3 SiCl, TMCS) in a cold, concentrated hydrochloric acid
(Wilcock 1949). Volatile cyclosiloxanes (H 2 SiO) n (n = 4–23) have been distilled off
from hydrolysis products of H 2 SiCl 2 (Seyferth et al. 1983). PMHS of the structure
Me 3 SiO[HSi(OSiMe 3 )O] n SiMe 3 have been prepared by the hydrolysis of trichlorosilane (HSiCl 3 ) with 80% sulfuric acid (H 2 SO 4 ). As a side product, octahydrosiloctasequioxane (T
H 8 , (HSiO 1.5 ) 8 ; H 8 Si 8 O 12 ) is obtained (Müller et al. 1959).
14.2 Synthesis of PHS and PMHS
Many types of polymerization methods have been useful for the synthesis of PHS
and PMHS: dehydrocondensation, ionic polymerization, polyaddition, polycondensation, redistribution (rearrangement, equilibration polymerization), dehydrocarbocondensation, thermal and catalytic depolymerization. The Si-H bond is quite stable
under acidic conditions and very unstable in the presence of oxygen, bases and
moisture (Lee 1966).
14.2.1 Synthesis of PMHS With Linear and Ring Structures
Linear and monocyclic PMHS are prepared by the following methods (White 1995;
Kricheldorf 1996; Chruściel 1999a; Brook 2000; Rościszewski and Zielecka 2002):
J. J. Chruściel