Electron microscopic and thermal studies of optically active 12-hydroxystearic acids in soap formation

Uzu, Yuhei; Sugiura, Toshio

doi:10.1016/0021-9797(75)90125-3

Cited by 31 publications

(15 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Two later studies suggest that the racemic mixture of 12HSA should produce platelets instead of fibers [16,17]. Uzu and Sugiura [16] found that platelets were formed only when the D/L ratio was one. More recent work by Terech, Rodriguez, Barns and McKenna [18] found no major differences between the gel forming ability of the pure enantiomer and the racemic mixture.…”

Section: Introductionmentioning

confidence: 98%

“…It appears, depending on the isomer used to produce the gel, that the molecule twists in different directions; the authors found no twist in the racemic mixture of the gelator [15]. Two later studies suggest that the racemic mixture of 12HSA should produce platelets instead of fibers [16,17]. Uzu and Sugiura [16] found that platelets were formed only when the D/L ratio was one.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Novel Cryo‐SEM Technique for Imaging Vegetable Oil Based Organogels

Rogers

Smith

Wright

et al. 2007

J Americ Oil Chem Soc

View full text Add to dashboard Cite

Gels were prepared by cooling dilute solutions (2% wt/wt) of 12-hydroxystearic acid (12-HSA) in canola oil and storing them at 30°C for 24 h. The gel's in-situ supramolecular network structure was imaged using four techniques: polarized light microscopy (PLM), 3-dimensional deconvolution polarized light microscopy (3DPLM), and cryo-scanning electron microscopy (cryo-SEM) of the xerogel and of an osmium tetroxide vapor fixed gel washed with isobutanol. Most of the canola oil was immobilized in the gel by fixation with osmium tetroxide therefore very little of the canola oil was removed during washing unlike the xerogel where all of the canola oil has been displaced. The in-situ supramolecular network structure as observed by PLM, was comparable to that seen through the new cryo-SEM method for fixed organogel. Cryo-SEM images of the xerogel did not show similar length scales or strand thickness as compared to the PLM images. The lengths of the network strands were much shorter for the xerogel as compared to the osmium tetroxide treated sample and the structures visualized by PLM. Furthermore, the thickness of the strands observed using PLM or cryo-SEM were in the size range of 3-10 lm while the xerogels had strands in the range of 0.01-0.1 lm thick. Therefore, the removal of canola oil from the gel using 80/20% v/v hexane/acetone with no fixation disrupted the supramolecular network.

show abstract

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

A Novel Cryo‐SEM Technique for Imaging Vegetable Oil Based Organogels

Rogers

Smith

Wright

et al. 2007

J Americ Oil Chem Soc

View full text Add to dashboard Cite

show abstract

“…On the other hand, a large number of low-molecular weight organic substances, such as metal soaps (1-9), 12-hydroxystearic acid (12HSA) (10)(11)(12)(13)(14), dibenzyliden sorbitol (15), long~hain dialkyl phosphates (16), amino acid derivatives (17)(18)(19)(20)(21) and steroid derivatives (22)(23)(24), are also known to form network structures in various organic media. On the other hand, a large number of low-molecular weight organic substances, such as metal soaps (1-9), 12-hydroxystearic acid (12HSA) (10)(11)(12)(13)(14), dibenzyliden sorbitol (15), long~hain dialkyl phosphates (16), amino acid derivatives (17)(18)(19)(20)(21) and steroid derivatives (22)(23)(24), are also known to form network structures in various organic media.…”

mentioning

confidence: 99%

Effect of alkali metal ions on gel formation in the 12‐hydroxystearic acid/soybean oil system

Tamura

Suetake

Ohkubo

et al. 1994

J Americ Oil Chem Soc

View full text Add to dashboard Cite

It has been known that 12-hydroxystearic acid (12HSA) forms a thermoreversible gel with a fibrous associated network in organic solvents. Mechanically durable gels were induced by the addition of small amounts of alkali metal ions, which can be supplied in the form of alkali metal salts of 12HSA (abbreviated as 12HS-M), even at a lower concentration range of gelling agent than with 12HSA alone. The structure of the networks was investigated by infrared spectrometry (IR), circular dichroism (CD) and scanning electron microscopy (SEM). The experiments were carried out over a total concentration range of 0.1 = 4.0 wt/vol% of 12HSA and 12HS-M in soybean oil. 12HS-Na showed more effective gel forming power than any other alkali metal ions. The molar ratio of 12HSA/12H~Na for obtaining optimal gel forming effect was 100:1. The intensity of the absorption bands of the IR spectra, due to the hydrogen-bonded hydroxyl groups, remained constant regardless of the amount of added 12HS-Na. A remarkable molar ellipticity decrease was observed with an increase in the concentration of 12HS-Na, although the maximum wavelength of the CD spectrum, originating from the chirality of 12HSA, remained constant. By SEM observation, linearly extended fibrils were observed with the addition of 12HS-Na. These results suggest that the mechanical strengthening of the gel by alkali metal ions is due to alteration of the dispersed state of the helically grown fibrous crystals of 12HSA.

show abstract

“…PLM has been previously used to examine the crystalline nature of ricinelaidic acid-canola oil gels (Elliger et al, 1972). The strands at 30°C have segmented areas of bright and dark zones which are related to the helical nature of the 12HSA strands (Fuhrhop, Schnieder, Rosenberg, & Boekema, 1987;Rogers, Wright, & Marangoni, 2008a, 2008bTachibana & Kambara, 1968;Terech, Rodrigues, Barns, & McKenna, 1994;Uzu & Sugiura, 1975). When the gels stored at 5 and 30°C are compared, the 30°C samples display thicker birefringent strands while the gels stored at 5°C have a diffuse matrix of very thin strands (Rogers,Wright, & Marangoni, 2008a, 2008b.…”

Section: Resultsmentioning

confidence: 99%