Hydrosilylation and dehydrocondensation reactions of methylhydridesiloxane to acrylic and methacrylic acids

Abstract

The hydrosilylation of a,o-bis(trimethylsiloxy) methylhydridesiloxane (degree of polymerization % 53) with acrylic and methacrylic acid with various ratios of the initial compounds, in the presence of platinum hydrochloric acid, has been investigated. In the presence of platinum hydrochloric acid, competitive dehydrocondensation reactions take place with the formation of various oligomers with various chemical links. In the later stages of the reaction, threedimensional systems have been obtained. During dehydrocondensation, the reaction order, reaction rate constants, and activation energy have been determined. The structures of the synthesized oligomers have been determined with IR and NMR spectroscopy data. Gel permeation chromatography, differential scanning calorimetry, and X-ray analyses of the synthesized oligomers have been carried out.

Formation of new thermoreactive polysiloxanes

“…It reacts with the (SiÀ ÀH group of the PMHS backbone with the elimination of hydrogen and producing Pt metal. This fact leads us to suggest that crosslinking also occurs according to the following scheme: [16][17][18] ð6Þ In the FTIR spectrum, we find signal with low intensity in the region 1187 cm À1 , which is characteristic for silsesquioxane bonds (SiO 3/2 ) and shows about side reactions due to crosslinking. Crosslinking in this way proceeds with low degree.…”

“…It reacts with the (SiH group of the PMHS backbone with the elimination of hydrogen and producing Pt metal. This fact leads us to suggest that crosslinking also occurs according to the following scheme:16–18 …”

“…We calculate activation energies ( U act ) and formation enthalpies ( H form ). Calculation method is described in our previous article 16. In Table III are presented the activation energies and the formation enthalpies for reaction according to hydrosilylation (anti‐Markovnikov rule and Markovnikov rule) and dehydrocondensation.…”

Nanocontact printing stamp material via bi-functionalization of polyhedral oligomeric silsesquioxanes

“…S5) presented peaks at d 5.64 ppm and d 5.00-4.94 ppm which correspond to H-atoms from the unreacted double bond of PA. These peaks did not disappear after the removal of the starting material under reduced pressure, suggesting that not only hydrosilylation of the double bond occurs but also oxysilylation (in literature also called dehydrocondensation) [38,39]. Moreover, in addition to the peak (0.3-0.6 ppm) for the methyl groups of the hydrosilylation product also a peak at 0.1-0.3 ppm for the methyl groups of the oxysilylation product occurred.…”

Hydrosilylation as an efficient tool for polymer synthesis and modification with methacrylates

“…19 The latter approach was used for the preparation of acrylate containing 20 and uorinated PDMS, respectively. 21 Hydrosilylation of h 2 PDMS systems was demonstrated as a technique for the introduction of (meth)acrylic acid, 22,23 amine and epoxy terminal end groups. 24 The addition of Si-H can be favorably compared with thiol-ene chemistry (addition of S-H) which has been the focus of many publications in recent years.…”