Anionic Ring-Opening Polymerization of Trimethylsiloxy-Substituted 1-Oxa-2,5-disilacyclopentanes:  Synthesis of Trimethylsiloxy-Substituted Poly[1-oxa-2,5-disila-1,5-pentanylene]s

Abstract

2,5,5-Trimethyl-2-trimethylsiloxy-1-oxa-2,5-disilacyclopentane (I), cis-and trans-2,5-dimethyl-2,5-bis(trimethylsiloxy)-1-oxa-2,5-disilacyclopentane (II), and 2-methyl-2,5,5-tris(trimethylsiloxy)-1-oxa-2,5-disilacyclopentane (III) have been prepared from 1,3,5,7-tetramethylcyclotetrasiloxane (D4 H ) and vinylpentamethyldisiloxane, vinylmethylbis(trimethylsiloxy)silane, and vinyltris(trimethylsiloxy)-silane, respectively, by a two-step synthetic process. I, II, and III undergo anionic ring-opening polymerization (AROP) to yield poly[2,2,5-trimethyl-5-trimethylsiloxy-1-oxa-2,5-disila-1,5-pentanylene] (IV), poly[2,5-dimethyl-2,5-bis(trimethylsiloxy)-1-oxa-2,5-disila-1,5-pentanylene] (V), and poly[2-methyl-2,5,5-tris(trimethylsiloxy)-1-oxa-2,5-disila-1,5-pentanylene] (VI), respectively. I-VI have been characterized by 1 H, 13 C, and 29 Si NMR and IR spectroscopy. Polymer microstructures have been determined by 29 Si NMR. Molecular weights of I-III have been determined by GC/MS and by high-resolution mass spectrometry. Molecular weight distributions of IV-VI have been determined by GPC. Mn's have been independently determined by 1 H NMR analysis. The glass transition temperatures (Tg's) and thermal stability of these polymers have been determined by DSC and TGA, respectively. Chain transfer apparently limits the molecular weight of VI. IntroductionThere is interest in the synthesis of cyclosilaalkylenesiloxanes and in the cationic ring-opening polymerization of these to yield poly(silaalkylenesiloxane)s. 1 AROP of 2,2,5,5-tetramethyl-1-oxa-2,5-disilacyclopentane has been reported, 2-5 and the kinetics of this process has been studied. 6 2,2,5,5-Tetramethyl-1-oxa-2,5-disilacyclopentane has been used to prepare welldefined poly(R-methylstyrene)-b-poly(dimethylsiloxane) block copolymers by living anionic polymerization. 7 Polymerization of 2-(3′,3′,3′-trifluoropropyl)-2,5,5-trimethyl-1-oxa-2,5-disilacyclopentane and related systems gives elastomeric materials with excellent chemical resistance, electrical properties, and strength. 8,9 Bis(1-oxa-2,5-disilacyclopentane)s undergo AROP to yield nonshrinking polycarbosilane/siloxanes. 10,11 Despite this interest in 1-oxa-2,5-disilacyclopentanes and in AROP, no examples of polymerization of trimethylsiloxy (TMSO)-substituted 1-oxa-2,5-disilacyclopentanes have been reported.

23 Inorganic and organometallic polymers

“…The anionic ring-opening polymerisation (ROP) of strained 1-oxa-2,5-disilacyclopentanes has been reported. 29 Molecular dynamics simulations have been used to study the structure of liquid PDMS and the results were found to be in good agreement with data obtained using wide-angle X-ray scattering. 30 The chain dynamics of PDMS in its inclusion compound with γ-cyclodextrin were studied using fast-MAS solid-state NMR spectroscopy.…”

“…The synthesis and fluorescent properties of a pyrene end-functionalised PDMS have been investigated. 25 The mechanism of the cationic polymerisation of 2,2-diphenyl-4,4,6,6-tetramethylcyclotrisiloxane initiated by triflic acid has been studied using 29 Si NMR at the pentad level and statistical methods. 26 The results suggested that monomer addition giving symmetrical siloxane -OSiMe 2 -OSiPh 2 -OSiMe 2 -(68%) and unsymmetrical siloxane -OSiMe 2 -OSiMe 2 -OSiPh 2 -(32%) units dominated the chain growth process.…”

“…10 4 g mol Ϫ1 . The polymers were characterized by 1 H, 13 C and 29 Si NMR spectroscopy and their thermal properties evaluated using TGA and DSC. The anionic ring-opening polymerisation (ROP) of strained 1-oxa-2,5-disilacyclopentanes has been reported.…”

Synthesis and characterization of alt‐copoly(carbosiloxane)s containing oligodiphenylsiloxane segments

“…Poly(carbosiloxane)s are polymers that contain both siloxane (SiOSi) and carbosilane (SiC) bonds in the polymer backbone 1. Copoly(carbosiloxane)s are most frequently prepared by the ring opening of cyclosilaalkylenesiloxanes or by metal‐catalyzed addition reactions such as the Pt‐catalyzed hydrosilylation copolymerization of tetramethyldisiloxane and diallyldimethylsilane 1–5. Copoly(silarylene siloxane)s are usually prepared by condensation reactions between a 1,4‐bis(hydroxyldialkylsilyl)benzene and a suitable comonomer such as α,ω‐bis(chloro)oligodimethylsiloxane or α,ω‐bis(amino)oligodimethylsiloxane 6–10.…”

Coupling agents with 2,4,6,8-tetramethylcyclotetrasiloxane core – synthesis and application in styrene–butadiene rubber production

“…They might be regarded as silicon analogs of crown ethers, since they form different-sized rings of alternating silicon and oxygen atoms, with various side chains (R = hydrogen atoms, alkyl, or vinyl groups) attached to silicon. 12 These compounds are characterized by flexibility, high strength of Si-O bonds, and high reactivity under specified conditions in miscellaneous organic reactions, i.e., hydrolysis, 13 halogenation, 14 dehydrogenative couplings, 15,16 silylative coupling, 17,18 alkylative cleavage, 19 Piers-Rubinsztajn reaction, 20 ring-opening polymerizations, 21,22 and hydrosilylation. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] 8-Membered compounds such as DH 4 , because of the possible modification of peripheral Si-H groups by a hydrosilylation reaction, have opened access to several functional materials.…”