Comparison of thermal and cholesteric mesophase properties among the three kind of hydroxypropylcellulose (HPC) derivatives

Yamagishi, Tada Aki; Guittard, Frédéric; Godinho, M. H.; Martins, A. F.; Cambon, A.; Sixou, P.

doi:10.1007/bf00297413

Cited by 29 publications

(24 citation statements)

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“…Such cellulose derivatives (CD) often form lyotropic liquid crystalline (LC) phases, which are of the cholesteric type and originate essentially from semirigidity and chirality of the cellulose main chain. 1,2 The mesophase formation is observed in the concentrated solution of CDs at a volume fraction of polymer (vЈ) higher than that predicted by Flory's theory. It should be also emphasized here that vЈ is often strongly solvent dependent.…”

Section: Introductionmentioning

confidence: 80%

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: 80%

Thermotropic mesomorphism of selected (2-hydroxypropyl)cellulose derivatives

Wojciechowski¹

2000

J. Appl. Polym. Sci.

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“…50-70 wt% Gray 1976, 1980). With regard to thermotropic liquid crystals realized in melt without any solvents, several derivatives of HPC obtained by esterifying or etherifying the hydroxyl groups of HPC were reported to form stable chiral nematic phases that displayed iridescent colors over a range of temperatures (Guittard et al 1994;Hou et al 2000;Huang et al 2007;Ishizaki et al 2015;Kosho et al 1999;Ohlendorf and Greiner 2015;Ritcey and Gray 1988;Tseng et al 1981;Yamagishi et al 1994;Yamagishi et al 2006). Those HPC ester/ether series can serve as media for a thermal sensor, or a display or light reflection device adaptable to various temperature conditions.…”

Section: Introductionmentioning

confidence: 99%

“…For the thermotropics of alkyl esters (normal acylates) of HPC (Hou et al 2000;Huang et al 2007;Kosho et al 1999;Yamagishi et al 1994), we find the following general tendencies regarding the chiral nematic pitch P: (1) As the alkyl chain-length increases, the thermal range involving mesophase formation shifts downwards and the pitch P increases at a constant temperature; (2) P decreases with increasing degree of substitution (DS) for the acyl group; (3) the handedness of the supramolecular helical arrangement is always right-handed.…”

Section: Introductionmentioning

confidence: 99%

Thermotropic liquid crystalline properties of (hydroxypropyl)cellulose derivatives with butyryl and heptafluorobutyryl substituents

2018

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(Hydroxypropyl)cellulose (HPC) derivatives with butyryl (Bu) and heptafluorobutyryl (7FBu) substituents were prepared in various proportions of the Bu/7FBu groups and at a fixed total DS (DSBu + DS7FBu) of 3.0. Thermotropic liquid crystallinity of the derivatives (Bu7FBu-HPC) was investigated to specify the effect of the fluoroacylation on the mesophase behavior. Thermal transition data were collected using differential scanning calorimetry and polarized light microscopy. The Bu7FBu-HPC samples formed a chiral nematic phase between their glass transition and isotropization temperatures, Tg and Ti-a, respectively; these transition temperatures rose moderately as the 7FBu proportion increased (Tg = −44-−27 °C and Ti-a = 158-190 °C for DS7FBu = 0.04-1.60). The structural property of the mesophase was examined at 70 °C by circular dichroism and other optical measurements. The chiral nematic pitch (P) sensitively increased with increasing 7FBu proportion, while the supramolecular helical arrangement remained right-handed. Selective light-reflection colors were observed for the samples of DS7FBu = 0.04-0.8, covering an entire spectrum range from violet to red. Temperature dependence of P was also examined for selected samples below Ti-a, and it was found to increase with increasing temperature; however, there was no indication of inversion in the handedness of the helical structure. Wide-angle X-ray diffractometry revealed that the increases of P responding to the increases in DS7FBu and temperature were attributable to the decrease of the twist angle between adjacent thin nematic layers.

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“…[10] LCP of particular interest are thermotropic cholesteric LCPs which display reflective colors depending on the cholesteric pitch height. The cholesteric properties of the hydroxypropyl cellulose( HPC) ester can be modulated overawide range by different laterals ubstituents, [11][12][13] degree of substitution [14][15][16] and blending. [17,18] We recently introduced ac holesteric HPC ester with ac ontrolled number of thioether groups.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular Nanocomposites: Dual‐Functional Cholesteric Hydroxypropyl Cellulose Esters Chemically Linked to Gold Nanoparticles

et al. 2016

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Functionalization of metal nanoparticles with liquid crystal polymers (LCP) is attractive for the formation of supramolecular structures with unique physical properties. We discovered that the chemical linkage of a liquid crystalline thiolated cellulose ester (HPC‐MTP_80) to gold nanoparticles (AuNP) leads, by control of the supramolecular structure, to a novel concept for functional materials with practical applications. At a critical concentration ratio of only 1.7 mol % HPC‐MTP_80, on average, only single HPC‐MTP_80 functionalized AuNP exist, forming a LC phase. Pure HPC‐MTP_80 forms a cholesteric phase with a pitch in the range of visible light. The slow pitch formation enables usage as a protective sealing material. This property in combination with the temperature dependence of the pitch makes HPC‐MTP_80 a perfect sensor for temperature monitoring of sensitive products like valuable pharmaceutics. Even the presence of very small amounts of functionalized AuNP in the nanocomposite suppress the pitch formation in the range of visible light, providing access for a possible application as a sensitive AuNP detector.

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Comparison of thermal and cholesteric mesophase properties among the three kind of hydroxypropylcellulose (HPC) derivatives

Cited by 29 publications

References 0 publications

Thermotropic mesomorphism of selected (2-hydroxypropyl)cellulose derivatives

Thermotropic mesomorphism of selected (2-hydroxypropyl)cellulose derivatives

Thermotropic liquid crystalline properties of (hydroxypropyl)cellulose derivatives with butyryl and heptafluorobutyryl substituents

Supramolecular Nanocomposites: Dual‐Functional Cholesteric Hydroxypropyl Cellulose Esters Chemically Linked to Gold Nanoparticles

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