Controlling the electrostatic interaction using a thermal signal to structurally change thermoresponsive nanoparticles

Jun Akimoto*, Hsiu Pen Lin, Yaw-Kuen Li, Yoshihiro Ito

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The negatively charged thermoresponsive polymers poly(benzyl methacrylate)-b-poly(acrylic acid)-b-poly(N-isopropylacrylamide) (PBzMA-b-PAAc-b-PIPAAm) were prepared by reversible-addition fragmentation chain transfer polymerization. The polymer formed core-shell polymeric micelles possessing a thermoresponsive corona composed of PAAc-b-PIPAAm below the lower critical solution temperature (LCST) of the PIPAAm chain. The nonionic thermoresponsive polymeric micelle composed of PBzMA-b-PIPAAm exhibited extensive inter-micellar aggregation after the hydrophobic phase transition of the corona-forming PIPAAm chains. In contrast, insertion of the PAAc chain into the thermoresponsive micelle maintained its dispersibility above the LCST of PIPAAm because of the electrostatic repulsion between the micelles. The micelles with short PAAc chains suppressed the effect of the negative charge derived from PAAc below the LCST because of the extended PIPAAm chain on the micellar surface. In contrast, the negative charge property appeared due to collapse of the PIPAAm layer above the LCST. This thermoresponsive change in its electrostatic behavior enables the micelle to control the adsorption and desorption of oppositely charged molecules in response to the temperature change across the LCST.

Original languageEnglish
Pages (from-to)27-33
Number of pages7
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Volume577
DOIs
StatePublished - 20 Sep 2019

Keywords

  • Bioseparation
  • Charged polymer
  • Electrostatic interaction
  • Nanoparticle
  • Thermoresponsive

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