Recoverable shear strain of liquid crystal‐forming concentrated hydroxypropyl cellulose solutions

Suto, Shinichi; Mitamura, Junya; Sasaki, Yasuyuki

doi:10.1002/app.10724

Cited by 3 publications

(3 citation statements)

References 23 publications

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“…3 indicates that the gel-like (G 0 \ G 00 ) behavior at low concentration gradually becomes sol-like (G 0 [ G 00 ) as the temperature increases. The gel/sol transition temperature is approximately 55°C (Tixier et al 2005;Suto et al 2002).…”

Section: Resultsmentioning

confidence: 99%

Sol/gel transition and liquid crystal transition of HPC in ionic liquid

Rwei

Lyu

et al. 2008

Cellulose

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This work uses an ionic liquid (IL), 1-butyl-3-methylimidazolium acetate, as a solvent to study the sol/gel transition (SGT) and liquid crystal transition (LCT) of hydroxypropylcellulose (HPC) solution. The LCT concentration of HPC at room temperature is 7 wt%, which is slightly higher than its SGT concentration of 6 wt%. For HPC concentrations of over 7 wt%, three rheological approaches were utilized, and the parameters relaxation time, hysteresis ratio and loss modulus (G 00 ) are measured to determine the LCT temperature. The relaxation study concludes that the LC-critical concentration of HPC is 7 wt%. When HPC exceeds 7 wt%, the LC transition temperatures, ranging from 45 to 51°C, can be measured and are proportional to the HPC concentration. The rheological results are then confirmed by making observations under a polarized optical microscope. All results are highly mutually consistent. Most significantly, the rheological parameters adopted herein can be used as good indicators of the LC transition. Of those indicators, G 00 changes distinctly at the LCT point, and can thus be suggested to be the most helpful indicator in determining the LCT temperature.

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Section: Resultsmentioning

confidence: 99%

Sol/gel transition and liquid crystal transition of HPC in ionic liquid

Rwei

Lyu

et al. 2008

Cellulose

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“…HPC, which is synthesized by reaction between propylene oxide and natural cellulose, forms lyotropic LC in a wide range of solvents. [14][15][16] PEDOT has been indicated to exhibit the most promising electrochromic properties of the many redox-active conducting polymers (e.g., polythiophene, polypyrrole, and polyaniline). 17-20 HPC in water forms a right-handed helical N*-LC structure.…”

Section: Introductionmentioning

confidence: 99%

“…In the present research, the electrochemical polymerization of EDOT was carried out in a concentrated solution of hydroxypropyl cellulose (HPC) in water to prepare optically active PEDOT. HPC, which is synthesized by reaction between propylene oxide and natural cellulose, forms lyotropic LC in a wide range of solvents. − PEDOT has been indicated to exhibit the most promising electrochromic properties of the many redox-active conducting polymers (e.g., polythiophene, polypyrrole, and polyaniline). − HPC in water forms a right-handed helical N*-LC structure . The molecular structure of HPC is shown in Figure a.…”

Section: Introductionmentioning

confidence: 99%

Optically Active Electrochromism of Poly(3,4-ethylenedioxythiophene) Synthesized by Electrochemical Polymerization in Lyotropic Liquid Crystal of Hydroxypropyl Cellulose/Water: Active Control of Optical Activity

Goto

Akagi

2005

Chem. Mater.

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The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in a water solution of hydroxypropyl cellulose (HPC) as a polymer lyotropic liquid crystal (LC) gives polyEDOT*/HPC hybrid (PEDOT*/HPC) as an optically active polymer. Circular differential interference contrast (C-DIC) microscopy of the polymer reveals a well-resolved ordered structure, and circular dichroism (CD) measurements indicate a Cotton effect for the polymer film. PEDOT prepared using this chiral nematic LC field exhibits good electrochemical stability and switching between a dark blue reduced state and sky blue oxidized state with corresponding changes in Cotton effect. The polymer thus shows "electrochiroptical effect", such as optically active electrochromism, and repeating change in CD through electrochemical redox process. The proposed method represents a new technique for the preparation of chiral conducting polymer films.

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