Amphiphilic cellulose: Surface activity and aqueous self-assembly into nano-sized polymeric micelles

The aim of the present study was to design amphiphilic cellulose that can self-assemble into polymeric vesicle or as nontoxic surfactants. Sulfate was firstly introduced as hydrophilic groups, then the hydrophobic groups for three cellulose derivatives. Effects of the hydrophobic length on the surface tension and critical aggregate concentration (cac) were investigated by the conventional Wilhelmy plate method. Results showed that the cac value decreased from 0.28 to 0.08 wt% and the corresponding surface tension increased from 44 to 55 mN/rn when the hydrophobic chain length changed from C-8 to C-18. The aqueous self-assembly of the modified polymer was investigated using transmission electron microscopy (TEM) and dynamic laser scattering (DLS). Results showed that three cellulose derivatives were capable of forming polymeric micelles in water with an average particle diameter ranging from 20 to 67 nm. And the diameter of the nano-micelles was proportional to the length of hydrophobic chain under the experimental conditions. These amphiphilic polymers showed more remarkable shear shinning rheological behavior as expected since higher shear rates lead to disruptions of hydrophobic associations. These data suggest that the amphiphilic cellulose derivative may form nano-micelles and might find use as surfactant or a potential drug carrier. (C) 2008 Elsevier Ltd. All rights reserved.