Effects of placing negatively charged groups at the corona terminus on the aqueous dispersion stabilities for PCL-b-PEO block copolymer micelles

A series of diblock copolymers HO-PCLn-b-PEO32-RX (n = 51, 67, 109, R = -O(CH2)3S(CH2)2-, X = -CO2H, -SO3Na) were synthesized from the HO-PCLn-b-PEO32-CH2CHCH2 diblock copolymer precursor by thiol-ene click chemistry. These PCL-b-PEO diblock polymers with different terminal groups were used to form spherical micelles with narrow size distribution. Micelles from [PCLn-b-PEO32-RCO2]−Na+ and [PCLn-b-PEO32-RSO3]−Na+ are observed to give stable aqueous dispersions with much larger hydrophobic cores and higher solution ion concentrations than micelles from PCLn-b-PEO32-CH2CHCH2 where a neutral allyl group terminates the corona.