The micellar properties of cationic dodecyltrimethylammonium chloride (DTAC) in aqueous media in the presence of 15-crown-5ether (CR) have been investigated by conductivity measurements over the temperature range 288.15-308.15 K. The results of the ternary DTAC/CR/W system were analysed in comparison with the reported results of binary DTAC/W system. The critical aggregation concentration (cac) and degree of ionization of the micelles were determined from the conductivity measurements at different temperatures. Thermodynamic parameters for the micellar system were estimated by applying the charged pseudo-phase separation model. Micellisation was found to be spontaneous and entropy-driven.
Table of Contents
1. Introduction
2. Experimental
2.1 Materials
2.2 Methods
3. Results and Discussion
4. Conclusions
Research Objectives and Topics
This study investigates the effect of 15-crown-5 ether on the micellar properties of the cationic surfactant dodecyltrimethylammonium chloride (DTAC) in aqueous media. By employing conductivity measurements across a temperature range of 288.15-308.15 K, the research aims to determine the critical aggregation concentration (cac) and the degree of counterion dissociation, subsequently analyzing thermodynamic parameters to understand the spontaneity and driving forces of the micellisation process.
- Micellar behavior of cationic surfactants in the presence of macrocyclic additives
- Determination of critical aggregation concentration (cac) via conductivity techniques
- Analysis of thermodynamic parameters including free energy, enthalpy, and entropy
- Evaluation of temperature dependence on micellisation processes
- Application of the charged pseudo-phase separation model
Excerpt from the Book
Introduction
Surfactant organized assemblies have great potential applications in day to day life [1]. Surfactants have micellar properties, which are effected by addition of small amount of electrolytes, non-polar and polar organic compounds. The critical aggregation concentration (cac) results from the hydrophobic interactions between the non- polar parts, which forms the core of the micelles and a repulsion interaction between the polar head group. During the last decades, the study of the behavior of ionic surfactants has received much attention. The effect of different kinds of additives including macrocycles, on the micellisation has also been widely studied. In some applications, macrocyclic compounds are used along with the surfactants due to counterion complexation. Crown ethers are a versatile class of macrocyclic ligands. The property of complex formation along with the selectivity shown by crown ethers towards cations distinguishes them from most non-cyclic ligands. The formation of complexes between the crown ether cavity and the counterions is expected to lead to significant alterations of the micellar properties. However, not much investigation is reported in this field [2-16].
In the present work, efforts have been made to study the effect of addition of crown ether (15-crown-5) with wider temperature variations on the cac of aqueous solutions of cationic dodecyltrimethylammonium chloride (DTAC) using conductivity technique. In addition, the thermodynamic parameters, 0 ΔGm , 0 ΔHm and 0 ΔSm have also been estimated and analyzed in aqueous media.
Summary of Chapters
Introduction: Provides the scientific context regarding surfactant organized assemblies and identifies the research gap concerning the influence of crown ethers on the micellisation of ionic surfactants.
Experimental: Describes the materials used, including the specific purity grades of DTAC and crown ether, and details the conductivity measurement procedures in a thermostatic glass cell.
Results and Discussion: Details the findings from conductivity measurements, presenting the temperature dependence of the critical aggregation concentration and discussing thermodynamic parameters derived from the charged pseudo-phase separation model.
Conclusions: Summarizes that the micellisation process is entropy-driven and highlights the impact of crown ether interaction on the hydrophobic character and micellar behavior of DTAC.
Keywords
Crown ether, Dodecyltrimethylammonium chloride, Critical aggregation concentration, Degree of ionization, Conductivity measurements, Micellisation, Thermodynamic parameters, Charged pseudo-phase separation model, Entropy-driven, Aqueous media, Surfactant, Counterion complexation, Macrocyclic ligands, Micellar properties, Temperature dependence.
Frequently Asked Questions
What is the primary subject of this research paper?
The paper focuses on the micellar behavior of the cationic surfactant dodecyltrimethylammonium chloride (DTAC) when the additive 15-crown-5 ether is introduced in an aqueous environment.
What are the core thematic areas covered?
The study covers surfactant science, macrocyclic chemistry, conductivity-based analytical techniques, and the thermodynamics of micelle formation.
What is the central goal of this study?
The goal is to determine how the addition of crown ether alters the critical aggregation concentration and thermodynamic properties of DTAC micelles across varying temperatures.
Which scientific method is employed for the analysis?
The researchers utilized conductivity measurements to study association behavior, applying the charged pseudo-phase separation model to calculate thermodynamic parameters.
What does the main body of the paper discuss?
It details the experimental setup, the temperature-dependent conductivity data, the calculation of thermodynamic values like Gibbs free energy and enthalpy, and the interpretation of the entropy gain during micellisation.
Which keywords best characterize this work?
Key terms include Crown ether, Dodecyltrimethylammonium chloride, critical aggregation concentration, micellisation, and thermodynamic parameters.
How does the temperature affect the critical aggregation concentration in this study?
The study observed a gradual decrease in the critical aggregation concentration as the temperature increased, which is attributed to a reduction in the hydration of the hydrophilic group.
What is the significance of the entropy values found for the ternary system?
The positive entropy values indicate that the micellisation process is entropy-dominated, likely due to the destruction of structured water molecules around the hydrophobic surfactant chains.
Does the addition of 15-crown-5 ether influence micellisation?
Yes, the results indicate that the presence of crown ether facilitates the micellisation process compared to the binary DTAC/water system.
- Arbeit zitieren
- Rajni Garg (Autor:in), R.D. Singh (Autor:in), 2011, Effect of addition of crown ether on the micellar behavior of Dodecyltrimethylammonium Chloride in Aqueous media , München, GRIN Verlag, https://www.grin.com/document/183933
