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

Abstract

ABSTRACT 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.