Synthesis of spirocyclosiloxanes for transparent copolymer thermosets

Abstract

The use of multiple‐ring cyclic molecules to generate crosslinked polymeric materials takes the advantages of small molecular precursors directly, but is retarded by the need of exact reactivity matching between different components. This problem was overcome by use of spirocyclosiloxanes, which were synthesized through the Piers–Rubinsztjan reaction. The two‐level ring strain energies in these spirocyclosiloxanes help them accommodate a wide range of single‐ring cyclic molecules to form highly transparent thermosets. The rich library of spirocyclosiloxanes, single‐ring cyclic molecules, and catalysts makes this modular approach a promising method for the preparation of useful materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46370.

Tris(pentafluorophenyl)borane-catalyzed Hydride Transfer Reactions in Polysiloxane Chemistry—Piers–Rubinsztajn Reaction and Related Processes

“…The desired spirocyclosiloxanes were obtained in high yields when cyclohexane was used as the solvent. The same reaction performed in methylene chloride did not produce a significant amount of spirocyclosiloxanes [91]. The anionic copolymerization of such spirocyclosiloxanes with various cyclic siloxanes leads to the formation of highly transparent cross-linked elastomers [91].…”

“…The desired spirocyclosiloxanes were obtained in high yields when cyclohexane was used as the solvent. The same reaction performed in methylene chloride did not produce a significant amount of spirocyclosiloxanes [91]. A similar approach was used to prepare spirocyclosiloxanes that were obtained from commercially available tetrakis(dimethylsilyloxy)silane and two molar equivalents of various diorganodimethoxysilanes in the P-R reaction (Scheme 23).…”

“…The desired spirocyclosiloxanes were obtained in high yields when cyclohexane was used as the solvent. The same reaction performed in methylene chloride did not produce a significant amount of spirocyclosiloxanes [ 91 ].…”

“…The anionic copolymerization of such spirocyclosiloxanes with various cyclic siloxanes leads to the formation of highly transparent cross-linked elastomers [ 91 ].…”

“…Various polymers containing a cyclotetrasiloxane ring in the main chain can also be prepared by the hydrosilylation of the same monomer with difunctional olefins (Scheme 24). The anionic copolymerization of such spirocyclosiloxanes with various cyclic siloxanes leads to the formation of highly transparent cross-linked elastomers [91].…”