Effect of temperature on the association behavior in aqueous mixtures of an oppositely charged amphiphilic block copolymer and bile salt

Guanqun Du, Alessandra Del Giudice, Viveka Alfredsson, Anna M. Carnerup, Nicolae V. Pavel, Watson Loh, Giancarlo Masci, Bo Nyström, Luciano Galantini, Karin Schillén

Research output: Contribution to journalArticlepeer-review

3 Citations (SciVal)

Abstract

The association in aqueous mixtures of a thermoresponsive cationic diblock copolymer composed of poly(N-isopropylacrylamide) (PNIPAM) and poly(3-acrylamidopropyl)-trimethylammonium-chloride (PAMPTMA(+)) and the oppositely charged bile salt sodium deoxycholate (NaDC) is investigated at different compositions by light and X-ray scattering, calorimetry, and electrophoretic mobility measurements. Clouding reveals aggregation upon heating. The addition of NaDC to the copolymer solution lowers the temperature of the transition and increases its cooperativity. At high temperature and low NaDC fractions, mixed aggregates with a dehydrated PNIPAM-rich interior and a PAMPTMA(+)-rich shell partially neutralized by DC anions are formed. At high NaDC fractions, the aggregates present internal regularly spaced segregated nanoregions of dehydrated PNIPAM and PAMPTMA(+)/DC (microphase separation). The results suggest that the mixed aggregates have appealing composition-controlled thermoresponse. The system phase separates at body temperature and the highest NaDC fractions investigated, meaning in conditions accomplished when the use of the polymer as a bile salt sequestrant is hypothesized.

Original languageEnglish
Article number122871
JournalPolymer
Volume206
DOIs
Publication statusPublished - 2020

Subject classification (UKÄ)

  • Physical Chemistry

Keywords

  • Bile salts
  • Cationic thermoresponsive block copolymers
  • Oppositely charged polymer-surfactant systems

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