Synthesis of poly(methylphenylsiloxane) rich in syndiotacticity by Rh-catalysed stereoselective cross-dehydrocoupling polymerization of optically active 1,3-dimethyl-1,3-diphenyldisiloxane derivatives

Oishi, Motoi; Moon, Ji Yoon; Janvikul, Wanida; Kawakami, Yusuke

doi:10.1002/1097-0126(200101)50:1<135::aid-pi600>3.0.co;2-6

Cited by 29 publications

(13 citation statements)

References 27 publications

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“…Although the NMR spectra were not studied in detail, the existence of crystallinity was shown in the resulting polymer by WAXS. Oishi, Moon, Janvikul and Kawakami have reported the preparation of syndiotactic PMPS by a Rhcatalyzed stereoselective cross-dehydrocoupling polymerization of optically active 1,3-dimethyl-1,3-diphenyldisiloxane derivatives [11], however, the resulting polymers were somewhat low in number-average molar mass (3,100≤M n ≤ 7100 gmol −1 ). Kawakami has also written a helpful review of this work and of related polymer systems [12].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Isotactic Rich Poly(methylphenylsiloxane) by Living Anionic Ring-Opening Polymerization

Ahn

Clarson

2011

Silicon

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Linear poly(methylphenylsiloxane) (PMPS) was prepared by the living anionic ring-opening polymerization of cis-2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxane (cis-P 3 ). The resulting linear PMPS was shown by NMR to be highly stereoregular and remarkably high in meso-meso fraction and proposed isotactic content (~80%). Tetrahydrofuran (THF) was used as the solvent and it is noted that THF also acts as a promoter for the system by increasing the reactivity of the silanolate nucleophile at the end of the propagating chain. It is proposed that this increase in the reactivity occurs preferentially in the intermolecular (propagating) reaction. The evidence for this proposed hypothesis is the exclusive production of meso-meso and meso-racemic triads in the linear PMPS as evidenced by NMR. As the reaction temperature was increased, the rate of polymerization increased and yet the tacticity of the polymer was not affected. It is therefore clear that there was no significant amount of back-biting (intramolecular) reaction for the temperatures and time intervals studied here, despite the fact that ring-chain equilibration is commonly observed in ring-opening siloxane polymerizations. Had the reversion reaction been present, then scrambling of the chain stereoregular sequences would have been observed by an equilibration mechanism. It is well established that phenyl-phenyl interactions (π-π stacking)can stabilize certain local conformations in PMPS chains and hence we propose that these phenyl-phenyl interactions may prevent back-biting reactions for PMPS under the kinetic conditions employed here.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Isotactic Rich Poly(methylphenylsiloxane) by Living Anionic Ring-Opening Polymerization

Ahn

Clarson

2011

Silicon

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“…8,9 Optical rotation of (R,R)-1 was [α] 27 D = −3.80 (c = 1, CHCl 3 ), determined to be 100% ee by polarimeter and HPLC. Methyltris(dimethylamino)silane (2) was offered by Shin-Etsu Chemical Co., Ltd. …”

Section: Methodsmentioning

confidence: 99%

Formation of Poly(silsesquioxane) Gel Containing Optically Active 1,3-Dimethyl-1,3-diphenyldisiloxane as a Connecting Unit

Seino

Oishi

Imae

et al. 2002

Polym J

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Much attention has been paid in recent years to the fabrication of chiral separation materials based on silicon-containing polymers by incorporating chiral groups to either the side chain or the main chain. 1 However, chiral separation materials with chirality induced by asymmetric silicon atoms in the main chain have not been reported yet. We have prepared several optically active polymers having asymmetric silicon atoms in the main chain, 2-5 and are moving toward finding possible application of these polymers as a new class of chiral separation materials based on the property derived from the asymmetry of the silicon atom itself in the polymer backbone.Meanwhile, poly(silsesquioxane) is a kind of interesting silicon-containing polymers. It has been widely used as matrix for guest molecules 6 due to the unique properties such as high thermo-stability and chemisorption behavior. If optical activity is induced, the resulting poly(silsesquioxane) is expected to find new potential applications as enantiorecognitive separating membrane or chiral column packing materials.Recently, we reported the synthesis of optically active and stereoregular poly(siloxane) via polycondensation of optically active 1,3-dimethyl-1,3-diphenyldisiloxanediol with bis(dimethylamino)dimethylsilane. 7 This approach is expected to be applicable to the synthesis of optically active poly(silsesquioxane). Here, we report our preliminary observation on the first synthesis of optically active poly(silsesquioxane) gel having asymmetric silicon atom in the polymer network.

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“…25 In addition, as noted, ROP also produces appreciable amounts of cyclic byproducts as a result of backbiting, and the formation of ordered polymers is difficult. 26 Rather than ROP, perfectly alternating diphenyl-codimethyl siloxane copolymers can be made using a condensation polymerization 22,23,27 between diphenylsilandiol and dichlorodimethylsilane in the presence of a secondary (Table 1). Here too, the disadvantages of using chlorosilanes and bases are present.…”

Section: Introductionmentioning

confidence: 99%

Facile synthesis of phenyl‐rich functional siloxanes from simple silanes

Schneider

et al. 2020

Journal of Polymer Science

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Phenyl-rich silicone polymers are used for their excellent thermal properties and high refractive indices. Traditional syntheses of these polymers utilize cationic or anionic equilibration, which limits the molecular weights that can be achieved due, in part, to the coproduction of cyclic monomers that must be removed. Kinetically controlled processes may reduce the impact of these limitations, but require high temperatures, alkyllithium initiators and an inert atmosphere; precise structures are difficult to access. The Piers-Rubinsztajn reaction, combined with hydrolysis, allows the synthesis of highly ordered, Si-H terminated, phenyl-rich silicone homo-and copolymers comprised of phenylmethyl, diphenyl and, dimethylsilicone monomers. The processes are mild and permit a high level of structural control, including alternating copolymers with different levels of phenyl content (Ph/Si = 0.3-1.5) with molecular weights up to 100 kDa. Yet higher molecular weights could be achieved-M n up to 300 kDa-when phenyl-rich siloxanes were incorporated into block copolymers with dimethylsilicones (Ph/Si = 0.4). Unlike kinetic processes in which cyclic byproducts are formed by redistribution or backbiting (particularly at high conversion), in this process cyclics form near the onset of the reaction and only with low molecular weight starting materials (< 4 siloxane units).

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Synthesis of poly(methylphenylsiloxane) rich in syndiotacticity by Rh-catalysed stereoselective cross-dehydrocoupling polymerization of optically active 1,3-dimethyl-1,3-diphenyldisiloxane derivatives

Cited by 29 publications

References 27 publications

Synthesis of Isotactic Rich Poly(methylphenylsiloxane) by Living Anionic Ring-Opening Polymerization

Synthesis of Isotactic Rich Poly(methylphenylsiloxane) by Living Anionic Ring-Opening Polymerization

Formation of Poly(silsesquioxane) Gel Containing Optically Active 1,3-Dimethyl-1,3-diphenyldisiloxane as a Connecting Unit

Facile synthesis of phenyl‐rich functional siloxanes from simple silanes

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