Section 2 Applications

**83**

**Chapter 5**

**Abstract**

Modeling the Behavior of

*Manuel Alonso-Ferrer and Juan Carlos Mejuto*

present better adjustment values, with R2

artificial neural network

**1. Introduction**

Amphiphilic Aqueous Solutions

Two types of predictive models based on artificial neural networks (ANN) and quadratic regression model developed in our laboratory will be summarized in this book chapter. Both models were developed to predict the density, speed of sound, kinematic viscosity and surface tension of amphiphilic aqueous solutions. These models were developed taking into account the concentration, the number of carbons and the molecular weight values. The experimental data were compiled from literature and included different surfactants: i) hexyl, ii) octyl, iii) decyl, iv) tetradecyl and v) octadecyl trimethyl ammonium bromide. Neural models

under 2.93% (for all data), than the quadratic regression models. Finally, it is concluded that the quadratic regression and the neural models can be powerful prediction tools for the physical properties of surfactants aqueous solutions.

Amphiphilic compounds have a well-defined structure; two parts clearly differentiated that will determine the behavior in aqueous systems [1] and is the key factor to their relationship with the internal and the external interfaces in aqueous systems [1]. One part of the amphiphilic compound is hydrophilic and the other

In aqueous systems, the most important application of surfactants (in volume and economic impact terms), generally a long-chain hydrocarbon group is used as the hydrophobic group (although i) fluorinated, ii) oxygenated hydrocarbon or iii) siloxane chains can also be used) and an ionic or highly polar group as a head or hydrophilic group [3]. The different types of amphiphilic molecules can be differentiated according to the bonds between their two parts, hydrophilic and hydrophobic [2]. For example i) a hydrophilic head can be covalently bound to hydrophobic alkyl chain, whether single, double, or triple, also, ii) an amphiphilic bolaform is formed by two hydrophilic heads covalently linked with a hydrophobic alkyl chain and iii) a Gemini amphiphile is two surfactants covalently linked by their charged heads [2]. These compounds can be also classified based on the chemical nature of their hydrophilic group with subgroups according to the tail, so that, four basic categories can be defined: i) anionic, ii) cationic, iii) nonionic and iv) amphoteric (and zwitterionic) [3].

**Keywords:** amphiphiles, surfactants, physical properties, modeling,

part is hydrophobic [1, 2] and both are linked by a covalent bond [2].

values above 0.902 and AAPD values

*Gonzalo Astray Dopazo, Cecilia Martínez-Castillo,* 
