Single chain characterization of hydrophobically modified polyelectrolytesusing cyclodextrin/hydrophobe complexes

The characterization of hydrophobically modified alkali-soluble emulsions ( RASE) using conventional techniques such as gel permeation chromatography o r static light scattering is difficult because of the hydrophobic associati on. Two different approaches were taken to prevent the hydrophobic associat ion of HASE polymers in aqueous solution: (1)hydrolyze the polymer to dislo dge the hydrophobic constituents, and (2) use methyl-beta-cyclodextrin, whi ch has a hydrophobic cavity and a hydrophilic outer shell, to shield the hy drophobes from associating. Using these two approaches, the molecular weigh t (M-w), hydrodynamic radius (R-h), and radius of gyration (R-g) of single chains of these polymers were determined using gel permeation chromatograph y (GPC) and dynamic (DLS) and static (SLS) light scattering techniques. The molecular weight of the control polymer (i.e., polymers with similar compo sition but with no hydrophobe) is found to be similar to 7.0 x 10(5) g/mol. The molecular weights of these polymers with C8, C16, and C20 hydrophobes were found to be similar to 2.0 x 10(5) g/mol. By comparing GPC and SLS res ults, we were able to determine that, except for one chemical site, branchi ng or grafting did not occur in the polymer chain during synthesis.