Dilute solution properties and aggregation behavior of alternate hetero-arm copolymer brushes

Alternate hetero-arm copolymer brushes were synthesized by free-radical cop olymerizations of vinylbenzyl-terminated polystyrene macromonomers (PS-VB) with a methacryloyl-terminated poly(ethylene oxide) macromonomer (PEO-MA)/t in tetrachloride (SnCl4: Lewis acid) complex. Dilute solution properties of such hetero-arm copolymer brushes were investigated by static and dynamic light scattering. Effective diffusion coefficients D-eff for copolymer brus hes possessing large aspect ratios showed almost constant values in the ran ge of polymer concentrations 0-6 x 10(-3) g/cm(3). These results mean that copolymer brushes formed unimolecular structures even in a good solvent suc h as benzene. It was speculated from angular dependence measurements that i n solution copolymer brushes take geometrically anisotropic conformations s uch as cylinders. To determine the phase-separated cylindrical domains of a lternate copolymer brushes, we constructed large aggregates of copolymer br ushes in water. Consequently, alternate copolymer brushes seemed to lead se lf-assemblies among phase-separated hydrophobic PS domains. (C) 2001 Academ ic Press.