The Solution Properties of Some Polyoxyethylated Nonionic Substances in Aqueous and in Nonaqueous Solvents

Abstract

Unlike sorbitan and glycerol monostearates, alkylphenol derivatives of polyoxytheylene appear to be monodisperse in benzene when the solutions were examined by vapor pressure lowering. I n addition, the existence of micelles was not detected by light-scattering measurements in benzene with a few representative samples. In agreement with light-scattering data, the number average micellar weight in water decreased with increasing nuinber of ethylene oxide units per molecule. A difference of about a factor of 8 between weight and number average molecular weight appears to exist for materials of similar con~position. IYTRODUCTIONNonionic detergents which derive their hydrophilic properties from ethylene oxide interact in aqueous solutions forming micelles above a critical concentration. The number of monomers clustering together to form micelles is dependent on the temperature (1, 2) and to some extent on the homogeneity of the polyoxyethylene chain lengths (3).Although a linear relationship appears to exist between aggregation number (n) and the reciprocal of the average number of ethylene oxide units for compounds containing more than 10 such units (4,5), the micellar weight of surfactants of lower solubility rises sharply in water with decreasing numbers of hydrophilic groups (6). Thus departures from linearity occur that became particularly apparent a t high ethylene oxide ratios when a wide range of ethylene oxide content is examined. Large differences in micellar weights were found between cryoscopic (7) and light-scattering measurements (8) of commercial isooctylphenol derivatives of nine ethylene oxide units. Since evidence for the existence of differences in number ( * ' , ) and weight (M,) average molecular weight appeared for other nonionic surface active agents in nonaqueous solvents (9, lo), it was of considerable interest t o assess the solution properties of some alkylphenol derivatives of ethylene oxide in both aqueous and nonaqueous media.In the present communication a number of octylphenol -ethylene oxide adducts (Tritons) were examined wherein the number of ethylene oxide units varied from 3 to 30 with the hydrophobic constituent of the molecule remaining constant. Two nonylphenols, Triton K128 and DowFax 9N9, were examined in benzene by vapor pressure lowering. Triton N128, DowFax 9x9, and Triton X-45 were also examined in benzene by lightscattering measurements and some vapor pressure measurements were carried out with DowFax 9N9 in alcohol. A variety of polyoxyethylated alkylphenols with cloud points above 50' C were examined in water using a vapor pressure "Osmometer".A lauryl alcohol derivative of 23 (po1y)oxyethylene units (Brij 35)* in which nonequilibrium states were found in water by light-scattering measurements (11) was examined in water and in benzene a t 37' C and in alcohol a t 44'. Some measurements were

Synthesis and Properties of Siloxane-Polyether Copolymer Surfactants

“…Aggregation number or actual micelle size, as determined by vapor phase osmometer measurements, gave values of 4.7 for (Me)3SiOSi(Me)2-(CH2)3(C2H40)7.2Me and 3.4 for (Me)3Si0[Si(Me)20]3-Si(Me)2(CH2)3(C2H40)i6.3Me. Although low, these values are comparable to aggregation numbers of 4.4 to 13 reported for a series of octylphenol-and nonylphenol-ethylene oxide adducts in water (7).…”

“…While many of these copolymers are water-soluble and exhibit typical surface active properties, the SiOC bonds in these compounds are subject to hydrolysis particularly in the presence of acids or bases. Hydrolytically stable methylsiloxane-polyether copolymers have been prepared by the catalyzed addition of hydrosiloxane polymers to the unsaturated ethers of polyoxyalkylene glycols according to the general equation (7):…”

Acrylic Ester Polymers

“…The types of surfactants used in an emulsion polymerization span the entire range of anionic, cationic, and nonionic species. The most commonly used soaps are alkyl sulfates such as sodium lauryl sulfate [151-21-3], alkylaryl sulfates such as sodium dodecyl benzene sulfonate [25155-30-0], and alkyl or aryl polyoxyethylene nonionic surfactants (87,(101)(102)(103)(104). Product stability and particle size control are the driving forces which determine the types of surfactants employed; mixtures of nonionic and anionic surfactants are commonly used to achieve these goals (105)(106)(107)(108).…”