Salt-induced depression of lower critical solution temperature in a surface-grafted neutral thermoresponsive polymer

Young K. Jhon, Rajendra R. Bhat, Changwoo Jeong, Orlando J. Rojas, Igal Szleifer, Jan Genzer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

81 Scopus citations

Abstract

Quartz crystal microbalance with dissipation monitoring (QCM-D) is employed to determine the effect of salt on the volume phase transition of thermoresponsive polymer brushes. Changes in mass and viscoelasticity of poly(N-isopropylacrylamide) (PNIPAM) layers grafted from a QCM-D crystal are measured as a function of temperature, upon contact with aqueous solutions of varying salt concentrations. The phase-transition temperature of PNIPAM brushes, TC,graft, quantified from the QCM-D measurements is found to decrease as the concentration of salt is increased. This phenomenon is explained by the tendency of salt ions to affect the structure of water molecules (Hofmeister effect). However, in contrast to the linear decrease in phase-transition temperature upon increasing salt concentration observed for free PNIPAM, the trend in TC,graft for PNIPAM brushes is distinctively non-linear.

Original languageEnglish (US)
Pages (from-to)697-701
Number of pages5
JournalMacromolecular Rapid Communications
Volume27
Issue number9
DOIs
StatePublished - May 2 2006

Keywords

  • Atom transfer radical polymerization (ATRP)
  • Grafted polymers
  • Poly(N-isopropylacrylamide) (PNIPAM)
  • Polymer brushes
  • Quartz crystal microbalance (QCM-D)
  • Surface-initiated polymerization
  • Thermoresponsive polymer

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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