Relationship between helical aggregates and polymorphs in a 12-hydroxystearic acid gel: their thermal stability and formation kinetics

Takeno, H.; Yanagita, M.; Motegi, Yuho; Kondo, Shingo

doi:10.1007/s00396-014-3404-8

Cited by 21 publications

(19 citation statements)

References 34 publications

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“…Recently it has been reported that different polymorphs were formed for 12-HSA gels in different solvents [13]. More recently, we reported that different polymorphs appeared at different temperatures [14], for example, three (001) peaks ( 1,(001) , 2,(001) , and 3,(001) ) corresponding to long spacings of 46.5, 42.4, and 39.7Å, respectively, were observed for 12-HSA gels in phenylmethyl silicone and for a neat HSA prepared by a temperaturejump into different temperatures, and each crystal form was termed form I, form II, and form III [14]. Contrary to it, a different behavior was observed for 12-HSA gel in a different solvent; for example, our small-angle neutron scattering (SANS) and synchrotron SAXS studies revealed that the selfassembled structure of 12-HSA in toluene was not affected by concentrations of the gelator and temperatures, [15][16][17].…”

Section: Introductionmentioning

confidence: 74%

“…This result suggests that form II or form III was transformed into form I during the aging period. Thus, it has been shown that form I is most stable at RT for the ionogel, which is the same as a result of 12-HSA/phenylmethyl silicone gel [14]. However, the rate of the transformation from form II into form I for the ionogel was faster than that of 12-HSA/phenylmethyl silicone gel.…”

Section: Stability Of Crystal Forms In Gelsmentioning

confidence: 89%

“…1∼2 days) at RT after the cooling process. As pointed out in the previous paper, the retention time at a certain Advances in Materials Science and Engineering temperature is important because of stability of each crystal form [14]. The stability of each crystal form will be discussed later in detail.…”

Section: Structures Of Gels Prepared By Various Coolingmentioning

confidence: 92%

“…The scattering peak at 1,(001) became larger with the decrease of temperature. The peak positions of three (001) peaks for the ionogel are completely the same as those of neat 12-HSA [14]. We carried out the peak decomposition analysis for the (001) peaks and evaluated the percentage of each peak area as a function of temperature as shown in Figure 5.…”

Section: Real-time Structural Investigation Of Gels During a Slowmentioning

confidence: 99%

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Effects of Cooling Rates on Self-Assembling Structures of 12-Hydroxystearic Acid in an Ionic Liquid

Takeno

Kozuka

2017

Advances in Materials Science and Engineering

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We investigated effects of cooling rates on self-assembling structures and mechanical and electrochemical properties of 12-hydroxystearic acid (12-HSA) in an ionic liquid (IL), 1-allyl-3-butylimidazolium bis(trifluoromethanesulfonyl) imide ([ABIm][TFSI]). The mixture of 12-HSA with [ABIm][TFSI] had an upper critical solution temperature (UCST) above the solgel transition temperature, and the microstructure of the ionogel was significantly affected by cooling rates, where it was prepared. The twisted self-assembling structure was formed during a slow cooling process at a rate of 0.4 ∘ C/min, whereas spherical domains caused by the liquid-liquid phase separation and radiate fibrous structure were observed for the quenched gel. The real-time smallangle X-ray scattering (SAXS) measurements for the ionogel during a slow cooling process at a rate of 0.4 ∘ C/min presented three different (001) peaks arising from long spacings of 46.5, 42.4, and 39.7Å, which were also observed for SAXS curves of a neat 12-HSA. These results suggest that three polymorphic forms of 12-HSA are formed in the IL. The polymorphic form significantly affected the mechanical properties of the ionogel, whereas it did not affect the ionic conductivity. The ionic conductivity of the ionogel was close to that of a neat [ABIm][TFSI] irrespective of the polymorphic forms of 12-HSA.

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Section: Introductionmentioning

confidence: 74%

Section: Stability Of Crystal Forms In Gelsmentioning

confidence: 89%

Section: Structures Of Gels Prepared By Various Coolingmentioning

confidence: 92%

Section: Real-time Structural Investigation Of Gels During a Slowmentioning

confidence: 99%

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Effects of Cooling Rates on Self-Assembling Structures of 12-Hydroxystearic Acid in an Ionic Liquid

Takeno

Kozuka

2017

Advances in Materials Science and Engineering

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“…The morphology of the gelator fibres can be influenced by the solvent. 12‐HSA can exist as different polymorphs which is also known to affect the morphology of the fibres ,…”

Section: Resultsmentioning

confidence: 99%

Periodic Grating‐like Patterns Induced by Self‐Assembly of Gelator Fibres in Nematic Gels

2018

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Periodic orientation patterns occurring in nematic gels, revealed by optical and scanning electron microscopy, are found to be formed by spontaneous self-assembly of fibrous aggregates of a low-molecular-weight organogelator in an aligned thermotropic liquid crystal (LC). Self-organization into periodic structures is also reflected in a calorimetric study, which shows the occurrence of three thermoreversible states, namely, isotropic liquid, nematic and nematic gel. The segregation and self-assembly of the fibrous aggregates leading to pattern formation are attributed to the highly polar LC and to hydrogen bonding between gelator molecules, as shown by X-ray diffraction and vibrational spectroscopy. This study aims to investigate in detail the effect of the chemical nature and alignment of an anisotropic solvent on the morphology of the gelator fibres and the resulting gelation process. The periodic organization of LC-rich and fibre-rich regions can also provide a way to obtain templates for positioning nanoparticle arrays in an LC matrix, which can lead to novel devices.

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Structural and Solubility Parameter Correlations of Gelation Abilities for Dihydroxylated Derivatives of Long‐Chain, Naturally Occurring Fatty Acids

Zhang

Selvakumar

Zhang

et al. 2015

Chemistry A European J

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Creating structure-property correlations at different distance scales is one of the important challenges to the rational design of molecular gelators. Here, a series of dihydroxylated derivatives of long-chain fatty acids, derived from three naturally occurring molecules-oleic, erucic and ricinoleic acids-are investigated as gelators of a wide variety of liquids. Conclusions about what constitutes a more (or less!) efficient gelator are based upon analyses of a variety of thermal, structural, molecular modeling, and rheological results. Correlations between the manner of molecular packing in the neat solid or gel states of the gelators and Hansen solubility data from the liquids leads to the conclusion that diol stereochemistry, the number of carbon atoms separating the two hydroxyl groups, and the length of the alkanoic chains are the most important structural parameters controlling efficiency of gel formation for these gelators. Some of the diol gelators are as efficient or even more efficient than the well-known, excellent gelator, (R)-12-hydroxystearic acid; others are much worse. The ability to form extensive intermolecular H-bonding networks along the alkyl chains appears to play a key role in promoting fiber growth and, thus, gelation. In toto, the results demonstrate how the efficiency of gelation can be modulated by very small structural changes and also suggest how other structural modifications may be exploited to create efficient gelators.

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Relationship between helical aggregates and polymorphs in a 12-hydroxystearic acid gel: their thermal stability and formation kinetics

Cited by 21 publications

References 34 publications

Effects of Cooling Rates on Self-Assembling Structures of 12-Hydroxystearic Acid in an Ionic Liquid

Effects of Cooling Rates on Self-Assembling Structures of 12-Hydroxystearic Acid in an Ionic Liquid

Periodic Grating‐like Patterns Induced by Self‐Assembly of Gelator Fibres in Nematic Gels

Structural and Solubility Parameter Correlations of Gelation Abilities for Dihydroxylated Derivatives of Long‐Chain, Naturally Occurring Fatty Acids

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