Association behavior of one-end hydrophobically modified poly[N5 -(2 -hydroxyethyl) L-glutamine] in water/ethylene glycol mixed solvent

Amphiphilic polymers Cn-PHEG consisting of water-soluble poly[N^sup 5^-2-(hydroxyethyl) l-glutamine] (PHEG) and hydrophobic alkyl chain (carbon number n=12, 14, 16, or 18) attached at the PHEG terminal was prepared, and association behavior and structure of associate for Cn-PHEG in selective solvent (water/ethylene glycol mixed solvent) have been investigated. α-Helix content of PHEG block for all the polymers increased with weight fraction of ethylene glycol in the mixed solvent (W^sub EG^). By light scattering measurements, formation of a small micelle was suggested for C14-, C16-, and C18-PHEG when W^sub EG^=0. With the increase in W^sub EG^, appearance of a larger associate was revealed for C16- and C18-PHEG. Evaluated molecular weight and radius of gyration suggested that the micelle is star-like sphere when W^sub EG^=0 and worm-like cylinder when W^sub EG^=0.7. C12-PHEG did not demonstrate any distinct micellization behavior because of the weak hydrophobicity of C12 chain.[PUBLICATION ABSTRACT]