Synthesis and characterization of copolymers with the same proportions of polystyrene and poly(ethylene oxide) compositions but different connection sequence by the efficient Williamson reaction

The AB type diblock PS ‐ b ‐ PEO and ABA type triblock PS ‐ b ‐ PEO ‐ b ‐ PS copolymers containing the same proportions of polystyrene ( PS ) and poly(ethylene oxide) ( PEO ) but different connection sequence were synthesized and investigated. Using the sequential living anionic polymerization and ring‐opening polymerization mechanisms, diblock PS ‐ b ‐ PEO copolymers with one hydroxyl group at the PEO end were obtained. Then, using the classic and efficient Williamson reaction (realized in a ‘click’ style), triblock PS ‐ b ‐ PEO ‐ b ‐ PS copolymers were achieved by a coupling reaction between hydroxyl groups at the PEO end of PS ‐ b ‐ PEO . The PS ‐ b ‐ PEO and PS ‐ b ‐ PEO ‐ b ‐ PS copolymers were well characterized by 1 H NMR spectra and SEC measurements. The critical micelle concentration ( CMC ) and thermal behaviors were also investigated by steady‐state fluorescence spectra and DSC , respectively. The results showed that, because the PEO segment in triblock PS ‐ b ‐ PEO ‐ b ‐ PS was more restricted than that in diblock PS ‐ b ‐ PEO copolymer, the former PS ‐ b ‐ PEO ‐ b ‐ PS copolymer always gave higher CMC values and lower crystallization temperature ( T c ), melting temperature ( T m ) and degree of crystallinity ( X c ) parameters. © 2015 Society of Chemical Industry