Effect of Molecular Weight on Cloud Point of Aqueous Solution of Poly (ethylene oxide)–Poly (propylene oxide) Alternating Multiblock Copolymer

Abstract

A poly(ethylene oxide) (PEO)–poly(propylene oxide) (PPO) alternating multiblock (AMB) copolymer with various molecular weights was prepared via precipitation fractionation from an acetone/n‐hexane mixture. The cloud point (T_c) of the aqueous solution of PEO–PPO AMB copolymer decreased as the number‐average molecular weight of the sample increased. This phenomenon is generally observed for certain homopolymer systems having a lower critical solution temperature, such as PEO/water and poly(N,N‐diethylacrylamide)/water systems. The relationship between the T_c of the solutions and the number of monomer units of the AMB copolymer suggests that the Shultz–Flory theory is applicable to this system.

graphical abstract