Micelle formation of a nonamphiphilic poly(vinylphenol)-block-polystyrene diblock copolymer in ethyl acetate

The micelle formation of a poly(vinylphenol)-block-polystyrene diblock copolymer was studied in ethyl acetate, a nonselective solvent using α,ω-diamine. The copolymer formed micelles in ethyl acetate in the presence of a small amount of the α,ω-diamine. Light scattering studies demonstrated that the micellization was dependent on the grade, the bulkiness, and the conformation of the diamines. The copolymer needed more diamine with the increasing grade of the diamine, due to a decrease in the basicity of the diamine. The bulkiness of the diamines also reduced the efficiency of the micellization by hindering the formation of the hydrogen bond cross-linking. Similarly, the conformation of the diamine affected the micellization, since the conformation determined the intramolecular spatial distance between the animo groups. Trans-1,2-cyclohexanediamine was more effective than the cis-isomer to produce the micelles. Furthermore, (1S,2S)-(+)-1,2-cyclohexanediamine, one of the mirror image isomers composing the trans-isomer, was more effective in producing the micelles than the trans-isomer. The interaction between the mirror image isomers also obstructed the micellization. The micellization, coupled with the thermoresponsivity of the micelles, were influenced by the solvent quality. The dissociation of the micelles into unimers was suppressed in ethyl acetate, while the reconstruction was promoted, in comparison with those in 1,4-dioxane and THF.