Thermal Stability of Nonionic Surfactant Aggregates

Toerne, Kevin; Rogers, and Robin; Wandruszka, Ray von

doi:10.1021/la010559s

Cited by 28 publications

(28 citation statements)

References 15 publications

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“…The cloud point of nonionic surfactant indicates a phase separation that is due to the increase in aggregation number of the micelles and the low intermicellar repulsion that is a direct consequence of the dehydration of the oxyethylene groups in the polyoxyethylene chain with increasing temperature. 45 It depends on the structure of the nonionic surfactant (i.e. length of the polyoxyethylene groups) and any nonpolar compound solubilized.…”

Section: Discussionmentioning

confidence: 99%

Formulation and Characterization of Phytophenol-Carrying Antimicrobial Microemulsions

et al. 2007

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Phytophenols were solubilized in nonionic surfactant micelles to form antimicrobially active and thermodynamically stable microemulsions. Formulation of phytophenols in microemulsions has previously been shown to improve their antimicrobial activity in model microbiological and food systems. Carvacrol and eugenol were incorporated in micellar solutions of two nonionic surfactants (Surfynol® 485W and Surfynol® 465) by mixing at room temperature. Particle size of formed microemulsions was determined by dynamic light scattering, and structural information about the mixed micellar system was obtained by nuclear magnetic resonance spectroscopy (NMR). Uptake of carvacrol and eugenol in surfactant micelles as determined by ultrasonic velocity measurements was very rapid, e.g., below the maximum additive concentration, the phytophenols were completely solubilized in the micelles in less than 30 min. Depending on the surfactant-phytophenol combination, the self-assembled surfactant-phytophenol aggregates had mean particle diameters between 3 and 17 nm. Elucidation of the structure of aggregates by 1H NMR studies indicated that micelles had a "bracket-like" structure with phytophenols being located inside the palisade layer of the micelle in direct contact with adjacent surfactant monomers. Encapsulation of phytophenols in surfactant micelles enables the incorporation of large amounts of hydrophobic antimicrobials in aqueous phases. Formulation of antimicrobial microemulsions may thus offer a means to deliver high concentrations of phytophenols to the bacterial surfaces of foodborne pathogens to affect kill.

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Section: Discussionmentioning

confidence: 99%

Formulation and Characterization of Phytophenol-Carrying Antimicrobial Microemulsions

et al. 2007

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“…This enhanced MS solubilization may be due to the formation of large premicellar aggregates that have been often observed [19], [20], with which the herbicide would be interacting.…”

Section: Resultsmentioning

confidence: 95%

Factors Affecting the Design of Slow Release Formulations of Herbicides Based on Clay-Surfactant Systems. A Methodological Approach

et al. 2013

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A search for clay-surfactant based formulations with high percentage of the active ingredient, which can yield slow release of active molecules is described. The active ingredients were the herbicides metribuzin (MZ), mesotrione (MS) and flurtamone (FL), whose solubilities were examined in the presence of four commercial surfactants; (i) neutral: two berols (B048, B266) and an alkylpolyglucoside (AG6202); (ii) cationic: an ethoxylated amine (ET/15). Significant percent of active ingredient (a.i.) in the clay/surfactant/herbicide formulations could be achieved only when most of the surfactant was added as micelles. MZ and FL were well solubilized by berols, whereas MS by ET/15. Sorption of surfactants on the clay mineral sepiolite occurred mostly by sorption of micelles, and the loadings exceeded the CEC. Higher loadings were determined for B266 and ET/15. The sorption of surfactants was modeled by using the Langmuir-Scatchard equation which permitted the determination of binding coefficients that could be used for further predictions of the sorbed amounts of surfactants under a wide range of clay/surfactant ratios. A possibility was tested of designing clay-surfactant based formulations of certain herbicides by assuming the same ratio between herbicides and surfactants in the formulations as for herbicides incorporated in micelles in solution. Calculations indicated that satisfactory FL formulations could not be synthesized. The experimental fractions of herbicides in the formulations were in agreement with the predicted ones for MS and MZ. The validity of this approach was confirmed in in vitro release tests that showed a slowing down of the release of a.i. from the designed formulations relative to the technical products. Soil dissipation studies with MS formulations also showed improved bioactivity of the clay-surfactant formulation relative to the commercial one. This methodological approach can be extended to other clay-surfactant systems for encapsulation and slow release of target molecules of interest.

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“…The spectrum indicated two peaks of fluorescence induced by irradiations with wavelengths of 375 nm (the first vibronic band) and 386 nm (the third vibronic band). In general, the ratio in intensity between these peaks ( I l / I 3 ) is sensitive to the micro‐environmental polarity, and it has been known that I 1 / I 3 values for pyrene are ∼1.8 and 1.1 in hydrophilic and hydrophobic environments, respectively 16–18. The observed I 1 / I 3 ratio was 1.13 (= 70.1/62.2) to suggest that pyrene molecules added to the system were distributed preferentially into nano‐scale hydrophobic domains created by the associates formation of the polymer 3 .…”

Section: Resultsmentioning

confidence: 99%

Design of controlled releasing system: Synthesis of an amphiphilic copolymer endowed with acid‐labile side chains based on quaternarization of amine‐containing prepolymer with benzyl halide having acetal moiety

Morinaga¹,

Morikawa²,

Sudo³

et al. 2009

J. Polym. Sci. A Polym. Chem.

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A methacrylate having a hydrophilic poly(ethylene glycol) chain and 2‐(N,N‐dimethylamino)ethyl methacrylate were radically copolymerized to obtain a statistical hydrophilic copolymer having tertiary amino groups in the side chains. The obtained polymeric amine was quantitatively quaternarized by a benzyl chloride‐type molecule having an acetal moiety derived from geraniol, which is a hydrophobic alcohol widely used as a fragrance ingredient. The resulting copolymer, which had PEG chain and the quaternary ammonium moieties as hydrophiles and the acetal moieties as hydrophobes, exhibited amphiphilicity to form stable associates in water. The acetal moieties were stable for 30 days at pH 9, while they were gradually hydrolyzed at pH 4 to release geraniol continuously at least for 30 days, confirming the potential applicability of the copolymer to a controlled releasing system of functional molecules. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3241–3247, 2009

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Thermal Stability of Nonionic Surfactant Aggregates

Cited by 28 publications

References 15 publications

Formulation and Characterization of Phytophenol-Carrying Antimicrobial Microemulsions

Formulation and Characterization of Phytophenol-Carrying Antimicrobial Microemulsions

Factors Affecting the Design of Slow Release Formulations of Herbicides Based on Clay-Surfactant Systems. A Methodological Approach

Design of controlled releasing system: Synthesis of an amphiphilic copolymer endowed with acid‐labile side chains based on quaternarization of amine‐containing prepolymer with benzyl halide having acetal moiety

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