Micelle Formation of “Nonamphiphilic” Poly(vinylphenol-co-styrene) Random Copolymers by Hydrogen Bond Cross-linking by α,ω-Diamine

Abstract

Well-defined poly(vinylphenol-co-styrene) random copolymers (P(VPh-r-St)) were prepared by living radical polymerization mediated by 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The copolymers showed no micellization in 1,4-dioxane, the nonselective solvent. Dynamic light scattering demonstrated that the copolymers formed micelles in the presence of α,ω-diamine. The copolymer with the molecular weight of Mn=8690 and the VPh/St unit ratio of 0.50/0.50 produced the micelles with ca. 90 nm as a hydrodynamic radius at 0.2 of the molar ratio of 1,4-butanediamine (BDA) to the VPh unit. It was found that the micellization occurred by intermolecular aggregation through hydrogen bond cross-linking between the VPh units by BDA, because the hydrodynamic radius and the aggregation number of the micelles increased with an increase in the copolymer concentration. The hydrodynamic radius of the micelles decreased with increasing the molecular weight of the copolymer, supporting the micellization by the intermolecular aggregation. And further, the micellar size also decreased with a decreasing the VPh ratio in the copolymer at the molecular weight constant.