Dilute Solution Properties and Aggregation Behavior of Alternate Hetero-arm Copolymer Brushes.

Alternate hetero-arm copolymer brushes were synthesized by free-radical copolymerizations of vinylbenzyl-terminated polystyrene macromonomers (PS-VB) with a methacryloyl-terminated poly(ethylene oxide) macromonomer (PEO-MA)/tin tetrachloride (SnCl(4): 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 brushes possessing large aspect ratios showed almost constant values in the range of polymer concentrations 0-6x10(-3) g/cm(3). These results mean that copolymer brushes formed unimolecular structures even in a good solvent such as benzene. It was speculated from angular dependence measurements that in solution copolymer brushes take geometrically anisotropic conformations such as cylinders. To determine the phase-separated cylindrical domains of alternate copolymer brushes, we constructed large aggregates of copolymer brushes in water. Consequently, alternate copolymer brushes seemed to lead self-assemblies among phase-separated hydrophobic PS domains. Copyright 2001 Academic Press.