Thermoresponsive poly(γ-propyl-l-glutamate)-graft-(oligo ethylene glycol)s: Synthesis, characterization, and properties

A series of thermoresponsive poly(γ-propyl- L -glutamate)-graft-(oligo ethylene glycol)s (PPLG-g-OEGs) with different main-chain and side-chain lengths have been synthesized via copper-mediated alkyne-azide 1,3-dipolar cycloaddition between poly(γ-azidopropyl- L -glutamate)s (PAPLG) and propargyl terminated oligo ethylene glycols (Pr-OEGs). Fourier transform infrared spectrometer analysis revealed that PAPLG 10 adopted 39.4% β-sheet, 47.4% α-helix, and 13.2% random coil while PAPLG with longer main-chain length (DP = 37 and 88) and PPLG-g-OEGs adopted exclusive α-helix in the solid state. Circular dichroism analysis revealed that PPLG-g-OEGs adopted α-helical conformations with helicities in the range of 50∼100%. The thermoresponsive behaviors of PPLG-g-OEGs in water have been studied by dynamic light scattering. The polymer concentration, main-/side-chain length, and helicity collectively affected their cloud point temperatures. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 41022.