Thermotropic cellulose derivatives with flexible substituents. III. Temperature dependence of cholesteric pitches exhibiting a cholesteric sense inversion

Yamagishi, Toshio; Fukuda, Takeshi; Miyamoto, Takeaki; Ichizuka, Toshihiro; Watanabe, Junji

doi:10.1080/02678299008029204

Cited by 49 publications

(37 citation statements)

References 25 publications

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“…Several studies have appeared in the literature concerning the solid-state properties of CDs proving that the CDs can exhibit the LC-phases even in the absence of solvent. 1,[3][4][5] Recent studies on the dielectric and mechanical properties of (2-hydroxypropyl)cellulose (HPC) 6 as well as its cyanoethylated derivative 7,8 have shown that these CDs in the solid state are characterized by a complex morphology, consisting of crystalline, amorphous, and intermediate phases.…”

Section: Introductionmentioning

confidence: 99%

Thermotropic mesomorphism of selected (2-hydroxypropyl)cellulose derivatives

Wojciechowski¹

2000

J. Appl. Polym. Sci.

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ABSTRACT:The thermotropic mesomorphism of some cellulose derivatives (CD) based on the (2-hydroxypropyl)cellulose (HPC) was investigated. Three types of derivatives: two esters (PPC, HxPC) and cyanoethyl derivative (CEPC) were prepared. The X-ray diffraction patterns of CDs were compared with the differential scanning calorimetry, thermooptical, and mechanical measurements within a broad range of the temperature. Two relaxation processes ␣ a and ␣ m , observed in the solid state of HPC, are also exhibited by all CDs, however, at lower temperatures. The ␣ m relaxations, which indicate the transition from frozen anisotropic phase to mobile liquid crystalline (LC)-phase, are shifted towards the lower temperatures with a corresponding increase in the d-spacing of the poly(saccharide) main chains of CDs (as seen in the X-ray measurements). The transition temperature to isotropic phase T ni as well as glass transition temperature T g (␣ a -relaxation) of the investigated CDs depend on the interactions between the lipophilic side chains and the hydrophilic poly(saccharide) main chains of CDs. These interactions are determined by the length and polarity of the lipophilic side chains. The observed changes in the transition temperature to isotropic phase T ni for CDs is consistent with the assumption that LC-organization of the poly(saccharide) main chains is stabilized by the lipophilic side-chains system. A significant increase in the length of the lipophilic side chains leads to nonlinear conformation, thus reducing the influence of van der Vaals forces, and consequently lowering T ni . The polymer with high polarity lipophilic side chains (CEPC) exhibits higher T ni in comparison to the ester derivative PPC with the same length of the side chains but having lower polarity. The stabilization effect of the lipophilic side-chains system on the LC-organization of the poly(saccharide) main chains is determined by the dynamic balance between length and polarity of the lipophilic side-chains system.

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Section: Introductionmentioning

confidence: 99%

Thermotropic mesomorphism of selected (2-hydroxypropyl)cellulose derivatives

Wojciechowski¹

2000

J. Appl. Polym. Sci.

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“…By the same idea, TChLC was successfully prepared from cellulose. 3 In this paper, we present a third example of TChLC formed from poly[ndecyl-(S )-2-methylbutylsilane] (PS-1) with the following formula, Whose helical conformation has been well established. 4 Novel TChLC was proved in a relatively lower molecular weight sample of PS-1 (Mw= 11100, DPw=46, and Mwl Mn= 1.19) in the temperatue range above 70°C, by circular dichroism (CD), wide-angle X-Ray and optical microscopy measurements.…”

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confidence: 99%

First Observation of Thermotropic Cholesteric Liquid Crystal in Helical Polysilane

Watanabe

Kamee

Fujiki

2001

Polym J

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“…Most thermotropic cellulose derivatives form the right-handed helical structure, while some derivatives form the left-handed one. The occurrence of helical sense inversion induced by temperature has also been reported for the thermotropic oligomeric cellulose derivatives with a flexible side chain (Yamagishi et al 1990). Thus, the flexible side chain not only assists in the melting and the orientation of the cellulose backbone due to an increase in the mobility of the latter, but it also plays an important role in the formation of helical structures in cholesteric mesophases.…”

Section: Introductionmentioning

confidence: 91%

“…In addition, HPC itself (Shimamura et al 1981), HPC derivatives (Gray 1983), and the fully substituted cellulose derivatives with flexible side chains (Yamagishi et al 1988(Yamagishi et al , 1989(Yamagishi et al , 1990(Yamagishi et al , 1991 have been reported to readily melt and form thermotropic liquid crystalline mesophases with heating.…”

Section: Introductionmentioning

confidence: 98%

Preparation and cholesteric mesophase properties of (Butyl-co-pentyl) propylcellulose

2006

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Butyl and pentyl ether derivatives of (2-hydroxypropyl) cellulose (HPC) and butyl/pentyl mixed ethers of HPC (BPPC) with different alkyl compositions were prepared in nonaqueous solution and their thermotropic cholesteric properties examined. The temperature dependence and the composition dependence of the optical pitch, nP, were then determined for all of the ether derivatives. The molecular conformation and chirality of BPPC appeared to be to be variably smooth with the side chain composition of the polymer. The response rate of cholesteric configurational change of the thermotropic mesophases arising from a temperature jump from 45 to 75°C, was also determined. The transformation of the cholesteric mesophase formed by an equimolar ether derivative (BP-50) was faster than that of the cholesteric one formed by a single-alkyl (pentyl) ether derivative (BP-0). This seemed to be a general result reflecting a pseudo-copolymer effect of cellulose derivatives on the properties of their thermotropic cholesteric mesophases.

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Thermotropic cellulose derivatives with flexible substituents. III. Temperature dependence of cholesteric pitches exhibiting a cholesteric sense inversion

Cited by 49 publications

References 25 publications

Thermotropic mesomorphism of selected (2-hydroxypropyl)cellulose derivatives

Thermotropic mesomorphism of selected (2-hydroxypropyl)cellulose derivatives

First Observation of Thermotropic Cholesteric Liquid Crystal in Helical Polysilane

Preparation and cholesteric mesophase properties of (Butyl-co-pentyl) propylcellulose

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