Solution behavior of copolymers with poly(ethylene oxide) as the “hydrophobic” block

Abstract

Block copolymers containg poly(ethylene oxide) (PEO) have been widely used in biomedical applications. The PEO block is generally treated as the hydrophilic moiety. In this work, we demonstrated that PEO could serve as the “hydrophobic” block under certain conditions by using PEO-b-poly(vinyl alcohol) (PEO-b-PVA) as the example. Water is a non-selective solvent for both of the blocks, however, the addition of NaCl decreases the solubility of PEO in aqueous solution while it shows no effect on the PVA block. With the solubility of PEO being deteriorated by adding NaCl, PEO-b-PVA exhibited amphiphilic feature in aqueous solution with PEO being the “hydrophobic” block. Therefore, by just adding salts, uniform gel-like particles were formed by PEO-b-PVA of proper block ratio. These solid particles formed by dual hydrophilic copolymers with excellent biocompability may have great potential in biomedical applications.