Soap: The Polymorphic Genie of Hierarchically Structured Soft Condensed-Matter Products

Raut, Janhavi S.; Naik, Vijay M.; Singhal, Siddhant; Juvekar, Vinay A.

doi:10.1021/ie0714753

Cited by 13 publications

(17 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In industrial manufacturing processes, mixing (shear) is an important control parameter because it homogenizes multicomponent systems as well as enhancing the kinetics of crystallization. The present finding may be of interest to the food processing industry, where the solidification of edible fats and oils is essential when manufacturing margarine, reduced fat spreads, ice cream, chocolate (38), and honey (39), or in consumer industry when manufacturing bar soaps, personal care creams, toothpastes, and lubricant greases (40).…”

Section: Discussionmentioning

confidence: 99%

Reversible shear-induced crystallization above equilibrium freezing temperature in a lyotropic surfactant system

Rathee

Krishnaswamy

Pal

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

We demonstrate a unique shear-induced crystallization phenomenon above the equilibrium freezing temperature ðT o K Þ in weakly swollen isotropic ðL i Þ and lamellar ðL α Þ mesophases with bilayers formed in a cationic-anionic mixed surfactant system. Synchrotron rheological X-ray diffraction study reveals the crystallization transition to be reversible under shear (i.e., on stopping the shear, the nonequilibrium crystalline phase L c melts back to the equilibrium mesophase). This is different from the shear-driven crystallization below T o K , which is irreversible. Rheological optical observations show that the growth of the crystalline phase occurs through a preordering of the L i phase to an L α phase induced by shear flow, before the nucleation of the L c phase. Shear diagram of the L i phase constructed in the parameter space of shear rate ð_ γÞ vs. temperature exhibits L i → L c and L i → L α transitions above the equilibrium crystallization temperature ðT o K Þ, in addition to the irreversible shear-driven nucleation of L c in the L i phase below T o K . In addition to revealing a unique class of nonequilibrium phase transition, the present study urges a unique approach toward understanding shear-induced phenomena in concentrated mesophases of mixed amphiphilic systems.shear-induced phase separation | strongly binding counterions | coagels S hear is known to assist crystallization below the equilibrium freezing temperature in complex fluids like colloidal glasses (1, 2), dense granular suspensions (3), polymer melts (4, 5), micellar solutions of block copolymers (6), and multicomponent surfactant systems (7,8). Shear-driven crystallization is equally relevant for simple fluids like bulk metallic glasses (9), molecular liquids (10), and atomic systems (11). The general understanding is that shear lowers the energy barrier for nucleation and accelerates the growth of a stable crystalline phase from a metastable, amorphous/ isotropic solution at Peclet number Pe = σa 3 kBT > 1, where σ is the shear stress, a is the characteristic length scale, and k B T is the thermal energy (12). The crystalline phase primarily induced by the effect of flow on the internal structure and ordering of the constituents does not revert to the starting fluid state when the imposed shear is removed, indicating that the phenomenon is not a dynamic phase transition. In the present study, we report a unique phenomenon, where under steady shear, crystallization occurs above the equilibrium crystallization temperature ðT o K Þ in an isotropic mesophase ðL i Þ consisting of bilayers formed in a lyotropic surfactant system. Notably, above T o K , when the imposed shear is removed, the crystalline phase melts back to the starting L i phase.The studies were carried out in a cationic-anionic mixed surfactant system formed by SDS and the strong binding counter-ion paratoluene hydrochloride (PTHC) in water. At equilibrium, the organic counter-ion PTHC has the tendency to remain at the micelle-water interface, decreasing the spontaneous curvat...

show abstract

Section: Discussionmentioning

confidence: 99%

Reversible shear-induced crystallization above equilibrium freezing temperature in a lyotropic surfactant system

Rathee

Krishnaswamy

Pal

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Above the Krafft temperature the neutralized fatty acids self-assemble into micellar, vesicular, lamellar, and hexagonal phases. 1 Beneath the Krafft temperature only crystalline precipitate is formed. An unusual property of sodium soaps is their propensity to form curd fibers.…”

Section: Introductionmentioning

confidence: 99%

Assembly of sodium soap fibers and fibrillar particles triggered by dissolution of sodium chloride crystals

Zawko

Schmidt

2010

Soft Matter

View full text Add to dashboard Cite

Fatty acids in the presence of sodium ions are known to self-assemble into sodium soap fibers. Previous work has yielded these fibers only in the form of randomly entangled gels. Here, for the first time, we demonstrate a method to create discrete fibrillar particles from sodium soap fibers. Immersion of sodium chloride crystals in solutions of neutralized fatty acids causes the crystals to dissolve and release sodium ions. Release of sodium triggers the nucleation and assembly of fibers in the solution surrounding the dissolving crystal. This process ultimately yields fibrillar particles with brush layers of sodium soap fibers. The fibers are flexible ribbons that are 1 mm in width, 3 mm in height, and hundreds of microns in length. We extended our method to polystyrene microspheres by encapsulating them with thin shells of sodium chloride microcrystals. Microspheres coated with sodium chloride shells triggered the assembly of encapsulating fibrillar brush layers. Microspheres with such brush layers have dramatically increased surface areas and this property may be applicable to oral drug delivery systems.

show abstract

“…Recently, we reported the gelating ability of the acid and its ammonium salts in a wide range of liquids . The parent compound, stearic acid, is not an efficient gelator, although there is a recent report on its gels at high concentrations in sunflower oil, and sodium stearate is the major component of many soaps . However, there are no studies we have been able to find for the gelating ability of metal salts of D‐REA .…”

Section: Introductionmentioning

confidence: 94%

Gelating abilities of metal salts of ricinelaidic acid. Structural and rheological considerations

Zhang

Weiss

2018

J of Physical Organic Chem

View full text Add to dashboard Cite

The gelating abilities of metal salts of ricinelaidic acid (D‐REA), the trans isomer of the naturally occurring cis isomer, D‐ricinoleic acid, have been examined in a wide range of liquids. D‐REA is not a good gelator due to its bent shape and low melting temperature. Although upon the formation of metal salts aids aggregation of D‐REA, their gelating ability differs dramatically depending on the nature of the metal cation. The salts with nickel(II), copper(II), and zinc(II) are inefficient gelators, while the calcium salt can gelate various organic liquids and the sodium salt is an ambidextrous gelator. Also, gels of calcium and sodium salts in nitrobenzene and/or in water are among the few known examples with crystalline gelator networks that exhibit thixotropic behavior. Structural insights from FT‐IR and powder X‐ray diffraction indicate that the specific nature of interactions of the salts at their head groups leads to different packing arrangements and changes the strength of the driving forces for 1D growth from secondary interactions. A short comparison between the gelating abilities of the D‐REA and the corresponding salts from 9,10‐dioxooctadecanoic acid, an acid of related structure, is included as well. Insights into the relationships among the interactions at the metal carboxylate centers, their ability to form molecular gels, and the properties of their aggregated structures are provided.

show abstract

Soap: The Polymorphic Genie of Hierarchically Structured Soft Condensed-Matter Products

Cited by 13 publications

References 24 publications

Reversible shear-induced crystallization above equilibrium freezing temperature in a lyotropic surfactant system

Reversible shear-induced crystallization above equilibrium freezing temperature in a lyotropic surfactant system

Assembly of sodium soap fibers and fibrillar particles triggered by dissolution of sodium chloride crystals

Gelating abilities of metal salts of ricinelaidic acid. Structural and rheological considerations

Contact Info

Product

Resources

About