Study of amphiphilic poly(1-dodecene-co-para-methylstyrene)-graft-poly(ethylene glycol). Part II: Preparation and micellization behavior of the amphiphilic copolymers

Poly(1-dodecene-co-pMS) copolymers were brominated by HBr/H₂O₂ system with high selectivity at the methyl groups of pMS units. It was found that longer reaction time, higher pMS content, and lower molecular weight of the copolymers were helpful for higher degree of bromination. Through a modified Williamson ether synthesis, poly(ethylene glycol) monomethyl ethers (PEG) were grafted onto the brominated copolymers, and the amphiphilic poly(1-dodecene-co-pMS)-graft-PEG copolymers which can be readily dissolved in n-octane were successfully synthesized. Due to their amphiphilic characteristics, they can self-assemble spontaneously into reverse micelles in n-octane. Their micellization behaviors were investigated by fluorescence probe technique, transmission electron microscopy (TEM), and dynamic light scattering (DLS). The critical micelle concentrations of the three copolymers in n-octane were determined at about 1.26 × 10⁻⁴, 1.58 × 10⁻⁴, and 1.95 × 10⁻⁴ g ml⁻¹ by fluorescence measurements. The morphologies of micelles were preliminarily explored by TEM and were found to be spheres.