Aqueous Solutions of Sodium Deoxycholate and Hydroxypropylmethylcellulose: Dynamic Surface Tension Measurements

Avranas, Antonis; Tasopoulos, Vasilis

doi:10.1006/jcis.1999.6574

Cited by 32 publications

(13 citation statements)

References 27 publications

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“…16,27 In the presence of 0.5% HPC the C 1 decreases with respect to CMC observed for the SDS/HPC 2,28 and DC/HPC systems whereas an opposite trend is observed for CS/HPC. An earlier study 22 on the system DC/HPMC/NaCl 0.01 mol L -1 indicated no changes with respect to CMC of DC but in our work the higher ionic strength may have contributed to decrease the solubility of the system leading to aggregation at lower concentration. The CMC reduction indicates polymer-surfactant association however the increment of CMC does not exclude it.…”

Section: Resultscontrasting

confidence: 63%

“…The CMC reduction indicates polymer-surfactant association however the increment of CMC does not exclude it. 22,29 The latter case reflects a destabilization of the micelle. The cooperative degree of the aggregation leads to the sharpness of the steeper segment in the curves (Figures 2 and 3) which approximates both C 1 values (Table 1).…”

Section: Resultsmentioning

confidence: 99%

“…Up to our knowledge it has been studied only with (hydroxypropylmethyl)cellulose. 21,22 It was verified that the aggregation process was cooperative and that the aggregates were small, highly hydrophobic and with low surface charge density. 21 The addition of a very small amount of DC to an aqueous HPMC solution already changed the dynamics of the reduction of surface tension.…”

Section: Introductionmentioning

confidence: 94%

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Anionic surfactant aggregation with (Hydroxypropyl)cellulose in the presence of added salt

Martins

Silva

Becker

et al. 2006

J. Braz. Chem. Soc.

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Estudou-se a agregação de surfactantes aniônicos em soluções aquosas diluídas de (hidroxipropil)celulose (HPC) sob moderada força iônica (NaCl 0,1 mol L -1 ). Empregaram-se os surfactantes colato de sódio (CS), deoxicolato de sódio (DC) e dodecil sulfato de sódio (SDS). Observou-se decréscimo da concentração de agregação crítica (C 1 ) para SDS e DC em comparação à concentração micelar crítica (CMC), enquanto ocorreu aumento para CS, a 298 K. A viscosidade relativa apresentou um máximo para o sistema SDS/HPC, mas permaneceu constante para CS/HPC ou DC/HPC. Houve aumento da temperatura de turbidez para todos os sistemas. Utilizando-se espalhamento de luz dinâmico, verificou-se que, a baixas concentrações de surfactante, o modo rápido da HPC relaciona-se a agregados surfactantes/HPC e cadeias poliméricas curtas; a altas concentrações, a micelas livres. O modo lento relaciona-se a complexos surfactante/HPC ou a "clusters" de HPC. Nos sistemas sais biliares/HPC, o mecanismo de agregação pode ocorrer em duas etapas.The aggregation of different anionic surfactants in dilute aqueous solutions of (hydroxypropyl)cellulose (HPC) under moderate ionic strength (NaCl 0.1 mol L -1 ) was studied. The surfactants were sodium cholate (CS), sodium deoxycholate (DC) and sodium dodecylsulphate (SDS). By fluorescence probing, the critical aggregate concentration (C 1 ) decreased for SDS and DC in comparison to the critical micelle concentration (CMC) whereas it increased for CS at 298 K. The relative viscosity reached a maximum for SDS/HPC but remained constant for CS/HPC and DC/HPC. By light scattering, cloud points were verified to increase. By dynamic light scattering, it was concluded that, at low surfactant contents, the fast mode of HPC is related to surfactant/HPC aggregates and shorter HPC chains; at high contents, to free micelles. The slow mode is linked to interchain polymer-surfactant complexes and HPC clusters. For the bile salts/ HPC systems, the mechanism of aggregation may occur in two steps.

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Section: Resultscontrasting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

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Anionic surfactant aggregation with (Hydroxypropyl)cellulose in the presence of added salt

Martins

Silva

Becker

et al. 2006

J. Braz. Chem. Soc.

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“…In the case of single PGA films (Figure 1), the surface pressure reached low values (up to 10 mN/m), and an increase in polysaccharide concentration (at 0.5 wt %) did not produce a significant additional increase in surface pressure, indicating that the interface must be saturated at a PGA concentration of 0.1 wt % 14. This behavior can be attributed to the large size of PS molecules, which leads to a restriction of the flexibility of the polymer segment at the interface and hinders an additional increase in surface pressure 24…”

Section: Resultsmentioning

confidence: 95%

Adsorption and rheological properties of biopolymers at the air‐water interface

et al. 2006

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“…It should be noted that WC values are dependent only on the surface tension (see Equation (4)). HPMC is a highly surface-active macromolecule and therefore surface tension of aqueous HPMC suspensions decrease as the HPMC concentration increases [19].…”

Section: Cohesion Work (W C ) Of Coating Formulationsmentioning

confidence: 99%

Surface Free Energy Utilization to Evaluate Wettability of Hydrocolloid Suspension on Different Vegetable Epicarps

et al. 2017

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Surface free energy is an essential physicochemical property of a solid and it greatly influences the interactions between vegetable epicarps and coating suspensions. Wettability is the property of a solid surface to reduce the surface tension of a liquid in contact with it such that it spreads over the surface and wets it, resulting from intermolecular interactions when the two are brought together. The degree of wetting (wettability) is determined by an energy balance between adhesive and cohesive work. The spreading coefficient (S cf/food ) is the difference between the work of adhesion and the work of cohesion. Surface wettability is measured by the contact angle, which is formed when a droplet of a liquid is placed on a surface. The objective of this work was to determine the effect of hydroxypropyl methylcellulose (HPMC), κ-carrageenan, glycerol, and cellulose nanofiber (CNF) concentrations on the wettability of edible coatings on banana and eggplant epicarps. Coating suspension wettability on both epicarps were evaluated by contact angle measurements. For the (S cf/food ) values obtained, it can be concluded that the surfaces were partially wet by the suspensions. S cf/food on banana surface was influenced mainly by κ-carrageenan concentration, HPMC-glycerol, κ-carrageenan-CNF, and glycerol-CNF interactions. Thus, increasing κ-carrageenan concentrations within the working range led to a 17.7% decrease in S cf/banana values. Furthermore, a HPMC concentration of 3 g/100 g produced a 10.4% increase of the S cf/banana values. Finally, S cf/fruit values for banana epicarps were higher (~10%) than those obtained for eggplant epicarp, indicating that suspensions wetted more the banana than the eggplant surface.

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Aqueous Solutions of Sodium Deoxycholate and Hydroxypropylmethylcellulose: Dynamic Surface Tension Measurements

Cited by 32 publications

References 27 publications

Anionic surfactant aggregation with (Hydroxypropyl)cellulose in the presence of added salt

Anionic surfactant aggregation with (Hydroxypropyl)cellulose in the presence of added salt

Adsorption and rheological properties of biopolymers at the air‐water interface

Surface Free Energy Utilization to Evaluate Wettability of Hydrocolloid Suspension on Different Vegetable Epicarps

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