Association behavior of poly(N,N-dimethylacrylamide)-graft-poly(methyl methacrylate) in dilute solution

Association behavior of poly(N,N-dimethylacrylamide)-graft-poly(methyl methacrylate) in dilute solution of mixed solvent of methanol/water has been investigated by using light scattering, where association strength of grafted chains is controlled by changing the water content. The following points are demonstrated: (1) the increase in water content in solvent starting from pure methanol increases the association strength, resulting in the formation of inter-molecular associations at water contents higher than 20–30 wt% of water, (2) the association number, Na, depends on the changing rate of water content of solvent. At higher changing rates, associates of small Na (=2–4) are formed by the dominance of intra-molecular association, while the slower change of water content yields larger associates of Na being of the order of 10. The presence of the optimum changing rate of solvent quality for inter-molecular associations is suggested. This process dependence of associate structure is discussed on the basis of association kinetics.