A Combined Experimental and Computational Study of the Substituent Effect on Micellar Behavior of γ-Substituted Thermoresponsive Amphiphilic Poly(ε-caprolactone)s

The effect of the core substituent structure on the micellar behavior of thermoresponsive amphiphilic poly(e-caprolactone) diblock copolymer micelles was investigated through a combination of experimental and computational methods. The polycaprolactone (PCL) amphiphilic block copolymers used in this study consisted of a hydrophilic poly{γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-e-caprolactone} block, which also endowed the polymer with thermoresponsiveness, and various hydrophobic poly(γ-alkoxy-e-caprolactone) blocks. Five different substituents have been attached to the γ-position of the e-caprolactone of the hydrophobic block, namely octyloxy, ethylhexyloxy, ethoxy, benzyloxy, and cyclohexylmethoxy, which self-assembled in aqueous media to generate the core of the micelles. All five synthesized diblock copolymers formed micelles in water and displayed thermoresponsive behavior with lower critical solution temperature (LCST) in the range of 36–39 °C. The impact of different substituents on the micelle proper...