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Polymer-Surfactant Interactions — Recent Developments
Published in E. D. Goddard, K. P. Ananthapadmanabhan, Interactions of Surfactants with Polymers and Proteins, 2018
A change in surfactant aggregation number compared to the value in the absence of polymer is an important indication of a polymer-surfactant interaction. Several techniques have been applied for the determination of aggregation numbers, and, in particular, techniques which make use of the solubilization of fluorescent probes in the micelles have become increasingly popular. Certainly, the addition of a probe may alter the behavior of the system as well as the structure, but comparisons with other methods have shown that, in most cases, the influence of an added probe (in submillimolar concentration) on the aggregates is small.
Cationic Gemini Surfactants as Genes and Drug Carriers
Published in Yasser Shahzad, Syed A.A. Rizvi, Abid Mehmood Yousaf, Talib Hussain, Drug Delivery Using Nanomaterials, 2022
Mays Al-Dulaymi, Anas El-Aneed, Ildiko Badea
Aggregation number is defined as the number of surfactant molecules forming a stable micelle upon reaching the CMC. Similar to CMC, aggregation number is impacted by all the structural elements of the gemini surfactants. In particular, increasing the head group polarity enhances hydration and results in an increased aggregation number. This was apparent in Borse et al. work in which the polarity of ammonium salt headgroups was increased by incorporating either one or two hydroxyl groups, resulting in an increase in aggregation number from 60 to 69 then to 75 (Table 14.2, group 1). (Devínsky et al. 1990).
Enhancing Uptake and Translocation of Systemic Active Ingredients
Published in Chester L. Foy, David W. Pritchard, and Adjuvant Technology, 2018
Roger J. Field, Farhad Dasigheib
The number of surfactant molecules per micelle, called the aggregation number, largely depends on surfactant structure and the nature of the surfactant hydrophile and hydrophobe. The most common surfactants with organic structures, have typical aggregate numbers ranging from 20 to 150. Organosilicone surfactants may have smaller aggregate numbers of around 5 to 31 and some do not form micelles.6,172,
Synthesis and properties of α-sulfo carboxyl disodium salt
Published in Journal of Dispersion Science and Technology, 2018
Yongqiang Sun, Lirong Ding, Jingjie Zhou, Martino Di Serio, Kehua Zhu, Yong Zhang, Huibin Liang, Huaping Wu, Jinyuan Sun
The number of surfactant molecule forming a micelle is defined as aggregation number. It is just a average molecular number of surfactant aggregation in micelles and can be used as a parameter reflecting the size of micelle. In order to explore the size of aggregation, steady-state fluorescence was measured. The fluorescence reading at 372 nm wavelength was recorded in the process. The average aggregation number can be obtained according to the formula[33]:
Analysis of asphaltene nano-aggregates formation using dynamic light scattering: Experimental and kinetic modeling
Published in Journal of Dispersion Science and Technology, 2023
Hamidreza Mallaki, Shahriar Osfouri, Reza Azin
According to this law, the relationship between the equilibrium concentrations of monomers and asphaltene aggregates is as follows: where is the constant of the mass action law, and are the equilibrium concentration of the aggregates, the equilibrium concentration of the monomers, and aggregation number, respectively. Asphaltene monomers are units that form asphaltene aggregates in asphaltene solutions. The aggregation number indicates the average number of molecules existing in a spherical micelle, or, for asphaltene, the number of monomers that form an asphaltene aggregate. The condition of mass balance for the whole system (single component) is written as follows: where is the total concentration of asphaltene monomers (concentration of asphaltene solution), is the degree of aggregation, and is the equilibrium concentration of monomers.[29] The aggregation of asphaltene monomers occurs continuously by increasing the number of monomers and proceeds to grow over time as stated by the following procedure: where n is the aggregation number.[30–32] This process involves elementary stages and the rate constant of the total reaction, K, is the product of elementary constants. Strictly speaking, they are all different; however, introducing geometric average K1, leads to express this constant as [29] By rewriting Equation (3) and also considering the following equations are obtained: