Organosilicon hydrides in macromolecular design: Reactions of chain-transfer and hydrosilylation

Use of Organohydridodisilanes for Controlling the Molecular-Weight Distribution of High-Conversion Polymers

“…At C s >> 1, the relative concentration of the chain-transfer agent [S]/[M] rapidly decreases in the course of the polymerization, which results in an appreciable decrease (by more than an order of magnitude in our case) in the apparent chain-transfer constant, in formation of a higher-molecular-weight polymer, and hence in the higher polydispersity of the final product. It should be noted in conclusion that similar effects can be expected in the case of polystyrene, as judged from the constants of chain transfer through disilanes in polymerization of styrene [4].…”

“…This result is undoubtedly associated with the abnormally high chain-transfer constant, C s = 8.3, due to the presence in the chain-transfer agent of a group of four silicon atoms located closely to the hydrogen atom. As shown in [4], polysilicon fragments in silanes activate the Si3H bond. At C s >> 1, the relative concentration of the chain-transfer agent [S]/[M] rapidly decreases in the course of the polymerization, which results in an appreciable decrease (by more than an order of magnitude in our case) in the apparent chain-transfer constant, in formation of a higher-molecular-weight polymer, and hence in the higher polydispersity of the final product.…”

“…The previously determined constants of the chain transfer through organosilicon hydrides [4] are given in Table 1. The molecular-weight characteristics of the polymers were determined by GPC …”

“…Therefore, it is urgent to find the conditions of radical polymerization ensuring preparation of polymers with fairly narrow MWD without decreasing the polymerization rate at acceptable temperature. For this purpose, we studied the molecular-weight characteristics of polymers prepared in the presence of polyfunctional silicon hydrides, which are effective chain-terminating agents for polymers [4].…”

A novel approach for the preparation of organic-siloxane oligomers and the creation of hydrophobic surface

“…In order to create a double bond in the molecule of siloxane oligomers, the reaction of hydrosilylation [26][27][28] was carried out. 22.2 g AM and 35.0 g toluene were added into a 500-mL flask before they were vigorously stirred and heated to 70 8C.…”