335
1. The hydrolytic polycondensation of methyldichloro(hydro)silane (MeHSiCl 2 ,
MDS) or copolycondensation with dimethyldichlorosilane (Me 2 SiCl 2 , DDS) and
TMCS (Brit. Pat. 632,954, 1949; Sauer 1952; Sokołow 1961; Rościszewski
et al. 1974, 1975; Richards et al. 1993);
2. The cationic polymerization (and copolymerization) of methylhydrocyclosiloxanes (D
H n ) (Reikhsfeld and Ivanova 1962; Graczyk and Lasocki 1978, 1979a, b;
Richards et al. 1993; Williams 1994) or their catalytic equilibration (linearization, repolymerization) with hexamethyldisiloxane (Me 3 SiOSiMe 3 , M 2 ) or
1,1,3,3-tetramethyldisiloxane (HMe 2 SiOSiMe 2 H, M
H 2 ), in acidic medium - with
protonic acids (e.g. CCl 3 COOH, CF 3 COOH, H 2 SO 4 , sulphonic acids) (Wilcock
and Hurt 1951; Husemann and Greber 1962; Stober et al. 1965; Lefort and
Parasko 1966; Gallagher 1966; Harris and Kimber 1974; Jap. Pat. 60,163,809,
1985; Crivello et al. 1986; Yamamoto and Matsuda 1991; Weiss 1993; Sellinger
and Laine 1996a, b; Hager 1996; Razzano et al. 1997; Nennendal et al. 1999;
Ganicz et al. 2004), with acidic salts (e.g. ammonium sulphate, (NH 4 ) 2 SO 4 ), cationits, protonic acid activated-clays (Husemann and Greber 1962; Reikhsfeld
and Ivanova 1962; Graczyk and Lasocki 1978; Crivello et al. 1986; Richards
et al. 1993; Sellinger and Laine 1996b; Nennendal et al. 1999), dimethylsilyl
sulphate (Razzano et al. 1997), Lewis acids (e.g. Al 2 (SO 4 ) 3 , CuSO 4 or Fe 2 (SO 4 ) 3 ),
and also with phosphonitrile halides (Nye et al. 1997, 1999);
3. The heteropolycondensation of siloxanediolates of alkali metals (Andrianov et al.
1962; Saxena et al. 2007; Zhang et al. 2007b) or siloxanediols (Chruściel and
Lasocki 1979) with hydrochlorosilanes, e.g. using chlorodimethylsilane
(HMe 2 SiCl, DMCS) in the presence of pyridine (C 5 H 5 N), as a hydrochloric acid
(HCl) acceptor, which leads to the production of PMHS with Si-H end groups.
The hydrolytic polycondensation of organic chlorosilanes is a multistep process,
including hydrolysis reactions of ≡Si-Cl bonds:
≡ −
≡ −
Si Cl
H O
Si OH
HCl
+
→
+
2
(14.1)
and series of consecutive reactions: heterocondensation of ≡Si-Cl groups with
silanol groups:
≡ −
− ≡
≡ − − ≡
Si OH
Cl Si
Si O Si
HCl
+
→
+
(14.2)
and homocondensation of silanol groups:
≡ −
− ≡
≡ − − ≡
Si OH
HO Si
Si O Si
H O
+
→
+
2
(14.3)
Hydrolysis reactions of hydrochlorosilanes are usually carried out at temperatures below 0 °C. α,ω-dichlorooligo(methylhydro)siloxane (Table 14.1) have
been synthesized at a much lower temperature (from −78 °C to room temperature RT) (Manami and Nishizaki 1958; Chruściel et al. 1997, Chruściel 1999b). α,ωdichlorooligo(methylhydro)siloxane are used in synthesis of PMHS with a regular
block structure. The side products of syntheses of PMHS (by polycondensation and
14 Hydrosilyl-Functional Polysiloxanes: Synthesis Reactions and Applications
1. The hydrolytic polycondensation of methyldichloro(hydro)silane (MeHSiCl 2 ,
MDS) or copolycondensation with dimethyldichlorosilane (Me 2 SiCl 2 , DDS) and
TMCS (Brit. Pat. 632,954, 1949; Sauer 1952; Sokołow 1961; Rościszewski
et al. 1974, 1975; Richards et al. 1993);
2. The cationic polymerization (and copolymerization) of methylhydrocyclosiloxanes (D
H n ) (Reikhsfeld and Ivanova 1962; Graczyk and Lasocki 1978, 1979a, b;
Richards et al. 1993; Williams 1994) or their catalytic equilibration (linearization, repolymerization) with hexamethyldisiloxane (Me 3 SiOSiMe 3 , M 2 ) or
1,1,3,3-tetramethyldisiloxane (HMe 2 SiOSiMe 2 H, M
H 2 ), in acidic medium - with
protonic acids (e.g. CCl 3 COOH, CF 3 COOH, H 2 SO 4 , sulphonic acids) (Wilcock
and Hurt 1951; Husemann and Greber 1962; Stober et al. 1965; Lefort and
Parasko 1966; Gallagher 1966; Harris and Kimber 1974; Jap. Pat. 60,163,809,
1985; Crivello et al. 1986; Yamamoto and Matsuda 1991; Weiss 1993; Sellinger
and Laine 1996a, b; Hager 1996; Razzano et al. 1997; Nennendal et al. 1999;
Ganicz et al. 2004), with acidic salts (e.g. ammonium sulphate, (NH 4 ) 2 SO 4 ), cationits, protonic acid activated-clays (Husemann and Greber 1962; Reikhsfeld
and Ivanova 1962; Graczyk and Lasocki 1978; Crivello et al. 1986; Richards
et al. 1993; Sellinger and Laine 1996b; Nennendal et al. 1999), dimethylsilyl
sulphate (Razzano et al. 1997), Lewis acids (e.g. Al 2 (SO 4 ) 3 , CuSO 4 or Fe 2 (SO 4 ) 3 ),
and also with phosphonitrile halides (Nye et al. 1997, 1999);
3. The heteropolycondensation of siloxanediolates of alkali metals (Andrianov et al.
1962; Saxena et al. 2007; Zhang et al. 2007b) or siloxanediols (Chruściel and
Lasocki 1979) with hydrochlorosilanes, e.g. using chlorodimethylsilane
(HMe 2 SiCl, DMCS) in the presence of pyridine (C 5 H 5 N), as a hydrochloric acid
(HCl) acceptor, which leads to the production of PMHS with Si-H end groups.
The hydrolytic polycondensation of organic chlorosilanes is a multistep process,
including hydrolysis reactions of ≡Si-Cl bonds:
≡ −
≡ −
Si Cl
H O
Si OH
HCl
+
→
+
2
(14.1)
and series of consecutive reactions: heterocondensation of ≡Si-Cl groups with
silanol groups:
≡ −
− ≡
≡ − − ≡
Si OH
Cl Si
Si O Si
HCl
+
→
+
(14.2)
and homocondensation of silanol groups:
≡ −
− ≡
≡ − − ≡
Si OH
HO Si
Si O Si
H O
+
→
+
2
(14.3)
Hydrolysis reactions of hydrochlorosilanes are usually carried out at temperatures below 0 °C. α,ω-dichlorooligo(methylhydro)siloxane (Table 14.1) have
been synthesized at a much lower temperature (from −78 °C to room temperature RT) (Manami and Nishizaki 1958; Chruściel et al. 1997, Chruściel 1999b). α,ωdichlorooligo(methylhydro)siloxane are used in synthesis of PMHS with a regular
block structure. The side products of syntheses of PMHS (by polycondensation and
14 Hydrosilyl-Functional Polysiloxanes: Synthesis Reactions and Applications