Cationic Heterogeneous Copolymerization of Octamethylcyclotetrasiloxane with 1,3,5,7-Tetramethyl-1,3,5,7-tetravinylcyclotetra-Siloxane: Optimization of Reaction Conditions

Abstract

Copolymerization of octamethylcyclotetrasiloxane (D4) with 1,3,5,7-tetrametyl-l,3,5,7-tetravinylcyclotetrasiloxane (V,) by heterogeneous acid catalysis has been carried out. In order to find the optimal conditions of the reaction, a second-order experimental design was performed with reaction time, reaction temperature, amount of catalyst, and the initial molar fraction of the mono-*

Synthesis and characterization of silicones containing cyanopropyl groups and their use in dielectric elastomer actuators

“…The molecular weight for the resulting polymer was determined by GPC (in chloroform), and gave the following values: M n = 59 140 g mol −1 , M w = 100 260 g mol −1 , with polydispersity index PDI = 1.7. The redistribution/equilibration reaction was done using heterogeneous cation exchanger catalysis [27,28] as described in the experimental part. After the redistribution, the molecular weight of the resulting copolymer b CoCN (4.3%) was determined by GPC in THF against polystyrene standards and gave the following values: M n = 81 722 g mol −1 , M w = 149 963 g mol −1 , PDI = 1.8.…”

Antibacterial Polysiloxane Polymers and Coatings for Cochlear Implants

“…2,2-dimethoxy-2-phenylacetophenone (DMPA, Merck, Darmstadt, Germany), N -acetyl- l -cysteine (NAC, Sigma-Aldrich, Saint Louis, Missouri, USA), diethoxydimethylsilane (Sigma-Aldrich, Darmstadt, Germany),dimethoxy-(3-mercaptopropyl)methylsilane (Sigma-Aldrich, Darmstadt, Germany), THF (Sigma-Aldrich, Darmstadt, Germany), and methanol (Sigma-Aldrich, Darmstadt, Germany) of high purity were used as received. Purolite CT-175 (sulfonated styrene-divinylbenzene cross-linked copolymer cationic exchange resins (St-DVB) with exchange capacity of 1.87 meq mL −1 was purchased from Viromet S.A. Dimethyl-methylvinylsiloxane copolymers (ViMSi) with 10 or 18 mol% methylvinylsiloxane units were prepared by a previously reported procedure [ 35 , 36 , 37 ].…”

From Amorphous Silicones to Si-Containing Highly Ordered Polymers: Some Romanian Contributions in the Field

“…The main fundamental research approached since the 90s has been aimed at: (a) techniques for polymerization and copolymerization of cyclosiloxanes (homogeneous catalysis, with thermolabile catalysts, heterogeneous catalysis, kinetics, molecular weight control, etc.) [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ]; (b) introduction of organic functions on silicon by various mechanisms (hydrosilylation, condensation, dehydrocoupling, thiol-ene addition, etc. ), study of their effects on the properties of the resulting compounds and evaluation of their functionality as blocks for siloxane-organic copolymerization [ 15 , 18 , 19 , 20 , 21 ]; (c) obtaining of block [ 22 , 23 ] or segmented [ 24 , 25 , 26 , 27 ] siloxane-organic copolymers with different internal functions (silyl ether, silyl ester, urethane, imide, amide, imine, etc.)…”

“…Multiple studies have been conducted by the authors on the hydrolysis-condensation of dichloro- or dialcoxy-functionalized diorganosilanes, to prepare and isolate either linear or cyclic oligodiorganosiloxanes having identical or different organic groups attached to the silicon atom, in order to be used as is or in further chemical transformations ( Figure 1 b). To obtain polydiorganosiloxanes in a wide range of molecular weights, ionic ring-opening polymerization en masse was performed, by either homogeneous or heterogeneous catalysis [ 11 , 12 , 13 , 14 , 15 , 16 , 40 ] ( Figure 1 c). The reaction conditions were optimized and the performances and limits of each system were assessed; useful information for choosing the appropriate pathway in each concrete case.…”