Small angle neutron scattering study on complex coacervate core micelles formed by oppositely charged poly(ethylene oxide-b-allyl glycidyl ether) block copolymer in water

Abstract

Structure of complex coacervate core micelles in aqueous solution formed by oppositely charged polyelectrolytes based on poly(ethylene oxide-b-allyl glycidyl ether) (PEOAGE) diblock copolymer was investigated using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). Two PEOAGE diblock copolymers are prepared by anionic ring-opening polymerization to provide PEOAGE-1 (Mn,PEO = 5000 g/mol and Mn,PAGE = 2700 g/mol) and PEOAGE-2 (Mn,PEO = 5000 g/mol and Mn,PAGE = 5500 g/mol). PAGE block in the diblock copolymer was functionalized with either primary amine or sulfonate group by thiol-ene click chemistry to generate two oppositely charged block copolyelectrolytes. In addition, unfunctionalized PAGE block is hydrophobic, and therefore PEOAGE block copolymer in aqueous solution forms hydrophobic driven micelles, which is used as control. Combination of DLS and SANS provides micelle dimension including overall micelle size, core radius, and aggregation number. Based on the results, hydrophobic driven micelles show relatively well-defined cores, and morphology changes from sphere to cylinder as PAGE block length increases. Spherical cores in complex coacervate core micelles are significantly swollen by water, and diffusive in comparison to hydrophobic driven micelles.