Effect of Molecular Composition of Head Group and Temperature on Micellar Properties of Ionic Surfactants with C12 Alkyl Chain

Abstract

The paper analyses influences of the temperature and hydrophilic groups on micellar properties of ionic surfactants with 12-carbonic hydrophobic chains. The aim is to assess the impact of hydrophilic groups and temperature on thermodynamic parameters and micellization. This knowledge is indispensable for the formulation of new dosage forms. The method uses conductometric measurements. The following hydrophilic groups are analyzed: trimethylammonium bromide, trimethylammonium chloride, ethyldimethylammonium bromide, didodecyldimethylammonium bromide, pyridinium chloride, benzyldimethyl-ammonium chloride, methylephedrinium bromide, cis and trans-[(2-benzyloxy)-cyclohexyl-methyl]-N, N-dimethylammonium bromide, sodium sulphate and lithium sulphate. Except for a few cases, there is a good agreement between values of critical micellar concentrations (CMC) and critical vesicle concentration (CVC) obtained here and those which were obtained by other authors and/or by other physicochemical methods. Values of the CMC are compared with respect to the molar masses of hydrophilic groups. It was found that CMC values increased non-linearly with increasing system temperature. The degrees of counterion binding and thermodynamic parameters, like the standard molar Gibbs energy, enthalpy and entropy of micellization are determined and discussed in detail. The results obtained will be incorporated into in silico processes of modeling and design of optimal dosage forms, a current interdisciplinary research focus of the team.

Natural Ergot Alkaloids in Ocular Pharmacotherapy: Known Molecules for Novel Nanoparticle-Based Delivery Systems

“…Surfactants are amphiphilic molecules comprising hydrophilic and hydrophobic portions in their composition. On the basis of the presence and absence of charged groups present in the head region, these molecules are characterized as being ionic and non-ionic, respectively [ 101 , 102 ]. Ionic surfactants are further categorized as (i) anionic (negatively charged), (ii) cationic (positively charged), or (iii) amphoteric (possess both negative and positive charge), depending on the charge in their head group [ 103 ].…”

Soft Cationic Nanoparticles for Drug Delivery: Production and Cytotoxicity of Solid Lipid Nanoparticles (SLNs)

“…Surfactants are defined as molecules with amphiphilic/amphipathic properties, having separate hydrophobic or solvophobic groups and hydrophylic or solvophilic properties. This feature arises from the chemical structure that consists of both a typically long alkyl chain (non-polar or hydrophobic groups, being named as "tails") and a polar or hydrophilic group (named as "heads") [10,11]. Surfactants are characterized by the presence or absence of charged groups in the head portion, being classified as ionic and non-ionic, respectively [9,10].…”

“…This feature arises from the chemical structure that consists of both a typically long alkyl chain (non-polar or hydrophobic groups, being named as "tails") and a polar or hydrophilic group (named as "heads") [10,11]. Surfactants are characterized by the presence or absence of charged groups in the head portion, being classified as ionic and non-ionic, respectively [9,10]. Depending on the total charge in the head group, ionic surfactants are further classified as (i) cationic, if positively charged, (ii) anionic, if negatively charged, and (iii) amphoteric, if presenting both a positive and a negative charge [11][12][13].…”

Micellization Behaviour of Conventional (Sds and Dtab) and Synthesized Gemini Surfactant (12-2-12) in Aqueous Solutions of Metformin Hydrochloride at Varying Temperatures: A Comparative Study

“…Also, augmentation in  values with different magnitude before (pre-micellar region) and after (post-micellar region) a particular point can be explained by the fact that the presence of micelles in the post micellar region restricts movement, resulting in a smaller contribution to conductivity than in the pre-micellar region, where only ions are present (no micelles). The intersection points between the two straight lines drawn in pre-and post-micellar regions gives the value of critical micelle concentration (CMC) [38]. Initially, Electrostatic and hydrophobic interactions after CMC formation play a crucial role in the development of micelles.…”