Association behavior of one-end hydrophobically modified poly[N 5-(2-hydroxyethyl) l-glutamine] in water/ethylene glycol mixed solvent

摘要

Amphiphilic polymers Cn-PHEG consisting of water-soluble poly[N 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 EG). By light scattering measurements, formation of a small micelle was suggested for C14-, C16-, and C18-PHEG when W EG = 0. With the increase in W 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 EG = 0 and worm-like cylinder when W EG = 0.7. C12-PHEG did not demonstrate any distinct micellization behavior because of the weak hydrophobicity of C12 chain.