rounded by three O atoms (general formula: [–RSiO 3/2 –] n ) and their molecules can
be of ladder or cage structure [2].
The most important representative of linear polysiloxanes is poly(dimethylsiloxane) (PDMS, R 1 = R 2 = CH 3 in the general formula) which nowadays is a
commercial, fabricated on a large industrial scale, widely applied material. PDMS is
characterized by high chain flexibility, very low glass transition temperature, low
dependence of physical properties on temperature, high hydrophobicity; it is used
as an ingredient of waterproof sealants, a range of household goods, cosmetics,
medical products, etc. [3, 4].
Formation of regular, ladder oligo- or polysilsesquioxanes is rather difficult, and
it requires specific synthetic routes [5]. Therefore, these compounds are not frequently investigated. In contrast, oligomeric silsesquioxanes of cage structures, the
so-called polyhedral oligomeric silsesquioxanes (POSS), especially the cubic ones,
can be synthesized in relatively high yields and give rise to a great scientific interest
[6]. In numerous studies, these uniform, nano-sized molecules have been covalently
bound to the main or side chains of or blended with organic polymers giving
composites [7–9]. The presence of POSS in the systems leads to the improved
thermal resistance and mechanical properties of the host materials. It should be
noted that apart from cubic oligomeric silsesquioxanes, compounds of similar cage
structure but containing four O atoms around each Si atom are also the topic of
many investigations. Although sometimes they are classified as POSS, they are in
fact silicates. Hence, correctly they should be named spherosilicates.
The most common substituents attached to Si atoms in organosilicon compounds
containing Si–O bonds are hydrocarbon groups (alkyl, phenyl, vinyl); in some
molecules, there are also Si–H bonds. Out of these moieties, vinyl and Si–H ones
are especially important as they ensure reactivity which allows introducing various
organic groups into the parent compounds and, in this way, altering their chemical
or physical properties. In particular, Si–H groups are necessary reagents in the
process called hydrosilylation which involves their catalytic addition to carbon–
carbon, carbon–heteroatom, or heteroatom–heteroatom multiple bonds [10]. As
discussed in a review article by Boutevin et al. [11], hydrosilylation is the most
often applied reaction in the preparation of side group-functionalized polysiloxanes.
The present chapter reviews the work that has been done since the year 2000 on
the use of hydrosilylation to modify polysiloxanes, cubic oligomeric silsesquioxanes, and spherosilicates by organic groups. We limit, however, the discussion to
the addition of Si–H group-containing compounds to the ones with carbon–carbon
double bonds in their structure. The emphasis is put on the implementation of
spectroscopic methods in the studies. Results reported by other researchers are
mainly presented here. Our team has the experience predominantly in the application of hydrosilylation in the synthesis of various polysiloxane networks [12–15],
but recently we have started investigations on functionalization of polysiloxanes
with organic compounds by hydrosilylation. Some of their results are included in
the paper.
Organization of the chapter is as follows: First we describe briefly the
hydrosilylation process (Sect. 12.2), then the spectroscopic methods and the ways
362
A. Chechelska-Noworyta et al.
be of ladder or cage structure [2].
The most important representative of linear polysiloxanes is poly(dimethylsiloxane) (PDMS, R 1 = R 2 = CH 3 in the general formula) which nowadays is a
commercial, fabricated on a large industrial scale, widely applied material. PDMS is
characterized by high chain flexibility, very low glass transition temperature, low
dependence of physical properties on temperature, high hydrophobicity; it is used
as an ingredient of waterproof sealants, a range of household goods, cosmetics,
medical products, etc. [3, 4].
Formation of regular, ladder oligo- or polysilsesquioxanes is rather difficult, and
it requires specific synthetic routes [5]. Therefore, these compounds are not frequently investigated. In contrast, oligomeric silsesquioxanes of cage structures, the
so-called polyhedral oligomeric silsesquioxanes (POSS), especially the cubic ones,
can be synthesized in relatively high yields and give rise to a great scientific interest
[6]. In numerous studies, these uniform, nano-sized molecules have been covalently
bound to the main or side chains of or blended with organic polymers giving
composites [7–9]. The presence of POSS in the systems leads to the improved
thermal resistance and mechanical properties of the host materials. It should be
noted that apart from cubic oligomeric silsesquioxanes, compounds of similar cage
structure but containing four O atoms around each Si atom are also the topic of
many investigations. Although sometimes they are classified as POSS, they are in
fact silicates. Hence, correctly they should be named spherosilicates.
The most common substituents attached to Si atoms in organosilicon compounds
containing Si–O bonds are hydrocarbon groups (alkyl, phenyl, vinyl); in some
molecules, there are also Si–H bonds. Out of these moieties, vinyl and Si–H ones
are especially important as they ensure reactivity which allows introducing various
organic groups into the parent compounds and, in this way, altering their chemical
or physical properties. In particular, Si–H groups are necessary reagents in the
process called hydrosilylation which involves their catalytic addition to carbon–
carbon, carbon–heteroatom, or heteroatom–heteroatom multiple bonds [10]. As
discussed in a review article by Boutevin et al. [11], hydrosilylation is the most
often applied reaction in the preparation of side group-functionalized polysiloxanes.
The present chapter reviews the work that has been done since the year 2000 on
the use of hydrosilylation to modify polysiloxanes, cubic oligomeric silsesquioxanes, and spherosilicates by organic groups. We limit, however, the discussion to
the addition of Si–H group-containing compounds to the ones with carbon–carbon
double bonds in their structure. The emphasis is put on the implementation of
spectroscopic methods in the studies. Results reported by other researchers are
mainly presented here. Our team has the experience predominantly in the application of hydrosilylation in the synthesis of various polysiloxane networks [12–15],
but recently we have started investigations on functionalization of polysiloxanes
with organic compounds by hydrosilylation. Some of their results are included in
the paper.
Organization of the chapter is as follows: First we describe briefly the
hydrosilylation process (Sect. 12.2), then the spectroscopic methods and the ways
362
A. Chechelska-Noworyta et al.