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Specific counterion repercussions on the thermal, pH-response, and electrochemical properties of side-chain leucine based chiral polyelectrolytes
- Source :
- Langmuir : the ACS journal of surfaces and colloids. 30(44)
- Publication Year :
- 2014
-
Abstract
- Effects of counterions of side chain amino acid based polyelectrolytes (PEs) on the solubility in aqueous medium, pH responsiveness, thermal properties, and ionic conductivities have been appraised. Deprotection of the tert-butyl carbamate (Boc) group from poly(Boc-l-leucine methacryloyloxyethyl ester) [P(Boc-l-Leu-HEMA)] was carried out to produce PE with trifluoroacetate as an associative counteranion (1a). PEs with bis(trifluoromethylsulfonyl)imide and hexafluorophosphate counteranion were prepared through anion exchange reactions of 1a. Protonation of the neutralized polymer (2) obtained from 1a, followed by anion exchange, leads to the production of miscellaneous PEs bearing different counteranions, such as tetrafluoroborate, trifluoromethanesulfonate, chloride, and nitrate. Differential scanning calorimetry traces of the PEs reveal that the comparatively larger and weakly coordinated counteranions require less thermal energy to dissociate, and thus, the glass transition temperature (Tg) of the PEs fall off with an increase in the size of the counteranion. A remarkable conductivity of 2.1 mS/cm was obtained in deionized water when Cl(-) acted as the counteranion. Steric and electronic factors of the counteranion induce a change of transition pH in different PEs, although the chiroptical nature was retained, as confirmed by circular dichroism spectroscopy.
- Subjects :
- chemistry.chemical_classification
Tetrafluoroborate
Inorganic chemistry
Protonation
Surfaces and Interfaces
Condensed Matter Physics
Polyelectrolyte
chemistry.chemical_compound
chemistry
Hexafluorophosphate
Polymer chemistry
Electrochemistry
Side chain
General Materials Science
Counterion
Glass transition
Trifluoromethanesulfonate
Spectroscopy
Subjects
Details
- ISSN :
- 15205827
- Volume :
- 30
- Issue :
- 44
- Database :
- OpenAIRE
- Journal :
- Langmuir : the ACS journal of surfaces and colloids
- Accession number :
- edsair.doi.dedup.....2ad5459f2e40963857953b4cab9999ea