Preparation and properties of comb-like surfactants containing poly(ethylene oxide) methyl ether grafts

The comb-like Surfactants, poly(styrene-co-maleic anhydride)-g-(poly(ethylene glycol) monomethyl ether), poly(St-co-MA)-g-(M PEG), have been prepared using a macromonomer approach to get controlled molecular structures. The macromonomer (MAMPEG) was obtained by esterification of poly(ethylene glycol) monomethyl ether with maleic anhydride. Poly(St-co-MA)-g-(M PEG) with various molar ratios of St to MAMPEG (R) were then constructed by radical copolymerization. The comb-like structures of the surfactants were confirmed by infrared and H-1 nuclear magnetic resonance spectroscopy. It is found from gel permeation chromatography characterization that the molecular weight of the surfactants increases as R increases. The polydispersity index was in the range between 1.4 and 2.0 in all the cases. The surfactants with a higher St percentage are less soluble in water due to aggregation. The value of critical aggregation concentration (CAC) and the surface tension at the CAC (gamma(cac)) decrease as R increases. The steady-shear measurements show that the surfactant solutions at 50 g/L are dilatant fluids. In addition, it appears that there are two break points in the viscosity-shear rate curve. Both break points increase with increasing R. It can therefore be concluded that the properties of comb-like surfactants poly(St-co-MA)-g-(M PEG) are related to molecular structure. The results demonstrate that the properties of these comb-like surfactants can be tailored through appropriate molecular design. (C) 2009 Elsevier Inc. All rights reserved.