Thermotropic behavior of syndiotactic polymethylenes with alkyloxycarbonyl side chains

Tokita, Masatoshi; Shikinaka, Kazuhiro; Hoshino, Teruki; Fujii, Kyohei; Mikami, Jun; Koshimizu, Noboru; Sakajiri, Koichi; Kang, Sungmin; Watanabe, Junji; Shigehara, Kiyotaka

doi:10.1016/j.polymer.2012.12.072

Cited by 28 publications

(32 citation statements)

References 13 publications

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“…Syndiotactic polymethylene bearing alkyl side chains are believed to assume a rod-like helical conformation to exhibit thermotropic properties, although no hard evidence of this helical conformation has been obtained. 17 A rigid-rod backbone SCLCP should therefore be obtained by attaching mesogens at the ends of the alkyl side chains of syndiotactic polymethylene. Thus, we investigated the thermotropic LC structures of P5CPn polymethylenes consisting of polymethylene backbones and 4-pentylcyclohexyl-phenoxy mesogens attached to each backbone carbon atom with n methylene spacers, where n is an even number ranging from 2 to 14 (Chart 1).…”

Section: ■ Introductionmentioning

confidence: 99%

Thermotropic Behavior of Syndiotactic Polymethylenes with ω-[4-(trans-4-Pentylcyclohexyl)phenoxy]alkyloxycarbonyl Side Chains

et al. 2015

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A series of syndiotatic P5CPn polymethylenes was prepared with 4-(trans-4-pentylcyclohexyl)phenoxy moieties linked to each backbone carbon atom via an alkyloxycarbonyl spacer and with even numbers of alkyl carbons n ranging from 2 to 14, and their thermotropic behaviors were investigated. The P5CPn, except P5CP2, formed smectic phases in which the rod-like polymethylene backbones were arranged in rectangular lattices, and the sidechain mesogens were aggregated into layers parallel to the shorter sides of the rectangular lattices. The packing of the mesogens changed with decreasing temperature from smectic C-like to smectic I-like (SmI-like) for n = 4−8 and from smectic Alike to SmI-like for n = 10−14. In the SmI-like phases, each mesogen along the main-chain axis was connected to every sixth backbone carbon atom, revealing a correlation between the packing of the mesogens and the main-chain conformation of a 3/2 helix. Conversely, P5CP2 formed a smectic phase with the main chains arranged in rows and with the mesogens barely aggregated into layers due to the short spacers.

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Section: ■ Introductionmentioning

confidence: 99%

Thermotropic Behavior of Syndiotactic Polymethylenes with ω-[4-(trans-4-Pentylcyclohexyl)phenoxy]alkyloxycarbonyl Side Chains

et al. 2015

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“… 47 Subsequent studies by Tokita, Shikinaka, Ihara, and co-workers confirmed that PEA and related syndiotactic polymers of diazoacetates show thermotropic liquid crystalline behavior due to a rod-like helical conformation in the polymer backbone. 48 − 50 The syndiotactic polymer pM 5 is likely to form similar triple helices, and the forces keeping the aggregates together are likely to be stronger in such triple-helix aggregates than in the atactic material, leading to a lower LCST for the syndiotactic polymer than for the atactic material ( Figure 6 , bottom). Solvation into individual polymer chains in solution is enthalpy-driven, while formation of aggregates at higher temperature is an entropy-driven process, releasing water solvent molecules upon aggregation of the individual solvated polymer chains.…”

Section: Resultsmentioning

confidence: 99%

Aqueous Phase Separation Behavior of Highly Syndiotactic, High Molecular Weight Polymers with Densely Packed Hydroxy-Containing Side Groups

et al. 2018

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Herein we describe the Rh-catalyzed C1 polymerization of silyl-protected diazoacetates of the general formula HC(=N2)C(=O)O(CH2)xOSiR3, where x = 2–5. After polymerization and subsequent desilylation, syndiotactic polymers bearing a hydroxy-containing side group on every backbone carbon are obtained. The molecular weight of the desired polymers can be controlled via chain transfer with methanol during the polymerization. The produced polymers are compared to atactic analogues formed by [(η3-C3H5)PdCl]-catalyzed polymerization of silyl-protected diazoacetates with the same general formula. While the polymers produced by the Rh and Pd catalysts have the same hydrophilic/hydrophobic balance, the stereoregularity of the polymers formed by the Rh catalyst was found to be of influence on the thermoresponsive behavior of the polymer. The effect of this stereoregularity on the thermoresponsive phase separation behavior of the produced polymers in aqueous solution was investigated.

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“…The carbene precursors of diazoacetates were prepared from the corresponding alcohols and polymerized using previously published methods . The M w values and polydispersity indices for the atactic and stereoregular PPMO purified by high‐performance liquid chromatography were estimated by GPC to be 0.198 × 10 5 /2.05 × 10 5 and 1.46/1.50 respectively.…”

Section: Resultsmentioning

confidence: 99%

“…it was mentioned by Hetterscheid et al that PMs polymerized by rhodium‐based catalyst are of syndiotactic form (however, we expected from the study of Burns et al that rhodium‐catalyzed stereoregular PMs are syn − anti isomer). In our previous studies, the thermotropic liquid‐crystalline (LC) behaviors of highly stereoregular PMs were estimated under bulk conditions …”

Section: Introductionmentioning

confidence: 99%

Stiff and hierarchical chain nature of atactic and stereoregular poly(substituted methylene)s

Shikinaka

Suzuki

Masunaga

et al. 2018

Polymer International

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In this study, we estimated the chain nature of atactic and stereoregular poly(substituted methylene)s containing a phenylmethoxy side chain at each main‐chain backbone carbon atom using synchrotron X‐ray scattering to understand the topological and conformational properties of these rigid polymers. The atactic poly(substituted methylene) showed a linear chain nature. Contrastingly, the stereoregular poly(substituted methylene) exhibited a random coil structure. © 2018 Society of Chemical Industry

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Thermotropic behavior of syndiotactic polymethylenes with alkyloxycarbonyl side chains

Cited by 28 publications

References 13 publications

Thermotropic Behavior of Syndiotactic Polymethylenes with ω-[4-(trans-4-Pentylcyclohexyl)phenoxy]alkyloxycarbonyl Side Chains

Thermotropic Behavior of Syndiotactic Polymethylenes with ω-[4-(trans-4-Pentylcyclohexyl)phenoxy]alkyloxycarbonyl Side Chains

Aqueous Phase Separation Behavior of Highly Syndiotactic, High Molecular Weight Polymers with Densely Packed Hydroxy-Containing Side Groups

Stiff and hierarchical chain nature of atactic and stereoregular poly(substituted methylene)s

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