Synthesis and UCST-type phase behavior of OEGylated poly(γ-benzyl-l-glutamate) in organic media

A series of OEGylated poly(γ-benzyl- l -glutamate) with different oligo-ethylene-glycol side-chain length, molecular weight (MW = 8.4 × 10 3 to 13.5 × 10 4 ) and narrow molecular weight distribution (PDI = 1.12–1.19) can be readily prepared from triethylamine initiated ring-opening polymerization of OEGylated γ-benzyl- l -glutamic acid based N -carboxyanhydride. FTIR analysis revealed that the polymers adopted α-helical conformation in the solid-state. While they showed poor solubility in water, they exhibited a reversible upper critical solution temperature (UCST)-type phase behavior in various alcoholic organic solvents (i.e., methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, and isopropanol). Variable-temperature UV–vis analysis revealed that the UCST-type transition temperatures ( T pt s) of the resulting polymers were highly dependent on the type of solvent, polymer concentration, side- and main-chain length. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54 , 1348-1356