Aqueous solution behavior of thermoresponsive polyzwitterionic microgels based on poly(N-vinylcaprolactam) synthesized via RAFT precipitation polymerization

Pabitra Saha, Michael Kather, Sovan L. Banerjee, Nikhil K. Singha, Andrij Pich*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Web of Science)


A new route to synthesize stimuli-responsive poly(N-vinylcaprolactam) (PNVCL) microgels decorated with zwitterionic poly(sulfobetaine) (PSB) chains was developed, using reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization. The polyzwitterionic PSB macro-RAFTS of controlled molecular weight were synthesized by RAFT polymerization of sulfobetaine (SB). Using this method, macro-RAFTs with good control over the molecular weight could be achieved. The PSB macro-RAFTs, having different molecular weights (1000, 5000, 10,000 g/mol) and concentrations (1, 2, 2.5 mol%), were used along with different amount of the cross-linker N,N'-methylenebisacrylamide (BIS) (1.5 and 2.5 mol%) in the precipitation polymerization of PNVCL microgels to obtain varying amounts of surface-grafted polyzwitterionic chains of controlled length and variable cross-linking degrees. The successful incorporation of PSB macro-RAFTS into PNVCL microgels was characterized by FTIR and H-1 NMR studies. Increasing the PSB concentration and BIS content in the PNVCL microgels resulted in a linear increase in electrophoretic mobility (mu(e)) and volume phase transition temperature (VPTT). However, increasing the molecular chain length of the zwitterionic macro-RAFT resulted in a shift of VPTT towards lower temperatures. This kind of stimuli-responsive, polyzwitterion decorated PNVCL microgels can be a potential material for biomedical applications.

Original languageEnglish
Pages (from-to)195-204
Number of pages10
JournalEuropean Polymer Journal
Publication statusPublished - Sep 2019


  • Microgels
  • Precipitation polymerization
  • Sulfobetaine
  • Macro-RAFT

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