Structural and Transport Properties of Bola C-16 Micelles in Water and in Aqueous Electrolyte Solutions

Abstract

Aq. solns. contg. a bolaform surfactant [α,ω-(4,7,10,13-pentaoxa-16-azacyclooctadecane)hexadecane], with and without electrolytes were investigated as a function of surfactant concn. and ionic strength. Small angle neutron scattering (SANS), NMR self-diffusion, and other phys.-chem. methods were used. From the anal. of SANS data it was inferred that in water the surfactant forms slightly charged ellipsoidal micelles, because of the partial hydrolysis of amino groups. The aggregates grow with the increase of concn., becoming more elongated. Due to the selective complexing ability of aza crown ether units, significant differences were obsd. upon addn. of LiCl, NaCl, and HCl. LiCl gives rise only to a screening of electrostatic repulsion between micelles. NaCl, in addn. to the screening effect, induces a redn. of micelle aggregation no. as a consequence of the increased repulsion between charged headgroups. The micelle size redn. is much stronger in the presence of HCl, which screens the micelle interactions once the surfactant is completely in ionic form. The aforementioned effects increase, as expected, on increasing the electrolyte concn. They are in line with information on the complexation of sodium and proton by the aza crown units, inferred by ionic cond. and potentiometric findings

In vitro and in vivo evaluation of Bola-surfactant containing niosomes for transdermal delivery

“…Organic solvent was evaporated by using an Heidolph Laboratory Digital 4010 rotary evaporator (Heidolph Instruments GmbH & Co., Schwabach, Germany) and α,ω-hexadecyl-bis-(1-aza-18-crown-6) was extracted and crystallized by using a cold ether solution. Synthesized Bola surfactant was characterized by 1 H-NMR, FT-IR spectroscopy melting point, and presented physicochemical properties in agreement with previously reported investigations (Muzzalupo et al, 1996;Caponetti et al, 2004).…”

“…Among various components, amphiphiles bearing crown ethers were synthesized in an attempt to obtain new surfactants with biocompatible polar headgroups for particular technological applications. The latest generation of this kind of surfactants is represented by amphiphiles having two polar crown ether headgroups linked to both ends of a long alkyl chain (Muzzalupo et al, 1996;Caponetti et al, 2004). These amphiphiles are generally referred to as bolaform surfactants and can be anionic, cationic, zwitterionic or nonionic as a function of the kind of ion, which can be complexed by the two crown ether headgroups (McKenzie et al, 1987;Muzzalupo et al, 1996).…”

Structure of Bolaamphiphile Sophorolipid Micelles Characterized with SAXS, SANS, and MD Simulations

“…A large amount of work has been dedicated to the synthesis and characterization of bola systems; however, much less work has been devoted to a thorough structural study. In the context of micellar objects composed of bolaamphiphiles, ,,− advanced structural considerations of the micellar packing and bola distribution are rare. , Indeed, Nagarajan predicted the formation and structure of micelles composed of bolaamphiphiles, basing his hypotheses on the analysis of the packing parameter. Interestingly, he predicted the formation of spherical, cylindrical, and discoidal micelles, in which he imagined that the bolaform compound has two configurations: elongated, which induces transradial crossing of the end-groups; folded, under which the end-groups lie both on the same side.…”

NMR diffusometry and conductometry study of the host–guest association between β-cyclodextrin and dodecane 1,12-bis(trimethylammonium bromide)

“…Bolaform surfactants have attracted a lot of attention in both fundamental and application fields [1][2][3][4][5]. Some of the potential applications of bolaform surfactants are: micellar extraction of metal ions [6], the use as photosensitive molecules [7], and synthesis of ordered mesoporous silica structures for application in, e.g., catalysis [8].…”