An Investigation of the Micellar Phase of Sodium Sulfopropyl Octadecyl Maleate in Aqueous Sodium Chloride Solutions by Light Scattering Techniques. Evidence of Nearly Rodlike Micelles

Abstract

The micellar phase of sodium sulfopropyl octadecyl maleate (SSPOM) in aqueous solution in the presence of NaCl has been investigated by static and dynamic light scattering. Below 80 mmol/L NaCl, small micelles with a mean aggregation number of 180 and an effective ionization degree of 0.13 are detected. Their size is salt independent and they show a small shape asymmetry. At higher salt concentrations a spheroid-to-rod transition occurs and elongated micelles are detected. The light scattering measurements are interpreted by using a structural model of nearly rodlike particles. At 250 mmol/L NaCl the contour and persistence lengths are about 500 and 120 nm, respectively. For higher surfactant concentrations than 3 × 10-3 g/mL the scattering behavior features that of a network of entangled micelles. The measured data are described by simple power laws with exponents differing from those predicted for semidilute solutions of flexible chains which is suggested to result from the high stiffness of structures. The micelles are directly visualized by cryo-TEM.

Osmotic pressure of solutions containing flexible polymers subject to an annealed molecular weight distribution

“…The universal scaling of P and K with respect to density φ and mean chain-length N is shown to be identical to that of quenched polymers, in agreement with theory [6]. Specifically, we find that in the semidilute regime the power law scaling of the pressure P ∝ φ 2.3 and compressibility K ∝ φ −0.3 , in agreement with experimental findings in many solutions of giant micelles [2], but only for sufficiently flexible ones [14,15]. Whether or not rings are present does not seem to alter the scaling of the pressure in semidilute EP.…”

Characterization of mixed non-ionic surfactants n-octyl-β-d-thioglucoside and octaethylene–glycol monododecyl ether: Micellization and microstructure

“…According to the Rayleigh-GansDebye theory, the scattered intensity of light from a dilute solution of weakly interacting particles with dimensions small compared with the wavelength of the incident light (i.e. diameter < k 0 /20) may be approximated by [25,26]:…”

Linear aggregation and liquid-crystalline order: comparison of Monte Carlo simulation and analytic theory

“…Other early work considered worm-like micelles, formed either of amphiphilic molecules in water or microemulsions of water and oil which are stabilized by amphiphilic molecules. If the micelles are relatively stiff they can display liquidcrystal phases [13]; these systems have been the subject of extensive experimental study [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Liquid-crystal phases have also been observed in folic acid salts [29], guanosine derivatives [30,31], and nucleosome core particles [32].…”