Self-assembled microspheres driven by dipole-dipole interactions: UCST-type transition in water

Nobuyuki Morimoto, Kanna Muramatsu, Tetsuichi Wazawa, Yuichi Inoue, Makoto Suzuki

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


A double hydrophilic block copolymer, poly(ethylene glycol)-poly(3-dimethyl (methacryloyloxyethyl) ammonium propane sulfonate) (PEG-SB), is synthesized by reversible addition-fragmentation transfer (RAFT) polymerization using PEG methyl ether (4-cyano-4-pentanoate dodecyl trithiocarbonate) as a chain transfer agent. PEG-SB forms multi-layered microspheres with dipole-dipole interactions of the SB side chains as the driving force. The PEG-SB polymers show an upper critical solution temperature (UCST) and the UCST is controllable by the polymerization degree. The PEG-SB microspheres are dissociated above the UCST and then monodispersed microspheres (∼1 μm) are obtained when the solution temperature is decreased below the UCST again. The disassociation/ association of the microspheres is also controllable using the concentration of NaCl. These multi-responsive microspheres could be a powerful tool in the field of nano-biotechnology.

Original languageEnglish
Pages (from-to)103-108
Number of pages6
JournalMacromolecular Rapid Communications
Issue number1
Publication statusPublished - 2014 Jan


  • dipole-dipole interactions
  • microspheres
  • self-assembly
  • stimuli-sensitive polymers
  • upper critical solution temperature

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry


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