Mass, size and shape of micelles formed in aqueous solutions of ethoxylated nonyl-phenols

Abstract

The study was extended to analysis of mass, size and conformation of micelles formed in aqueous solutions of ethoxylated nonyl phenols. The results obtained by ultracentrifugal technique between 293 and 323 K have proved that the slightly ethoxylated nonyl phenols form micelles with high molecular mass and larger size at constant temperature, while the increasing length of the ethylene oxide chain favours formation of micelles of smaller molecular mass and size. The transformation of conformation from oblate to spherical shapes ensues with increasing temperature at constant ethoxy number or with ethoxylation at constant temperature. The second virial coefficient decreases with increasing temperature and decreasing ethoxy number. In accordance with the earlier conclucions, the change of the second virial coefficient relates to enhanced variation of monomer solubility, stabilization of micelle structure and increased deviation from ideal behaviour of a given micellar system.

Dielectric spectroscopy and micellization of aqueous solutions p-isononylphenoloxyethyleneglycolether

“…If the ethoxylation degree n eo and the hydrocarbon radicals were identical, the n aggr averages and their temperature dependences coincided, as was observed for NPEO-10-water [38] and Igepal Co-710 (n eo = 10.3)-water [48] systems within the temperature ranges of 293-323 and 283-308 K, respectively. Unfortunately, the micelle sizes and shapes were not determined in [48].…”

“…4(a), curve 2) have the same order of magnitude as the p obl values determined by the sedimentation [38] for NPEO-10 solutions with a concentration of 2 wt% (Fig. 4(a), curve 6); however, the trend of temperature dependences of p obl for these systems is opposite.…”

“…To answer the question which model (IIa or IIc) corresponds to the structure of dilute NOP-10 solutions, we used the results of the earlier study of systems with similar non-ionic surfactants [38,[42][43][44][45][46][47][48][49]. In accordance with the phase diagram of NP-10-water system ( Fig.…”

“…In that paper [7], the formation of spheroids in solutions with concentrations of 50 and 45 wt% Triton X-114 was justified. According to ultracentrifugation data [38], at the NPEO-10 concentrations lower than 2 wt%, micelles in water have the shape of oblate spheroids (Fig. 4(a), curve 6).…”

“…The size and shape of micelles are determined by the aggregation degree n aggr and hydration number Z of NOP-10 molecules [2][3][4][5][6][7]11]. The hydrodynamic diameter of the micelles of decaoxyethylene p-nonylphenol ether with unbranched hydrocarbon chain, p-CH 3 -(CH 2 ) 8 C 6 H 4 O(CH 2 CH 2 O) 10 H with n eo = 10 (NPEO-10, analog of NOP-10) was measured by ultracentrifugal technique between 293 and 323 K and varied from 68 to 92 A [38]. It can be expected that the sizes of NOP-10 micelles are the same order of magnitude (10 À6 cm).…”