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- Title
NMR Study of Thermoresponsive Block Copolymer in Aqueous Solution.
- Authors
Spěváček, Jiří; Konefał, Rafał; Čadová, Eva
- Abstract
Temperature behavior of D2O solutions of poly(ethylene oxide) (PEO)114- block-poly( N-isopropylacrylamide) (PNIPAm)109 is characterized by NMR methods. At temperatures above the lower critical solution temperature (LCST) transition of PNIPAm component, 1H NMR spectra are consistent with existence of micelles where immobilized PNIPAm blocks form rather compact core and mobile PEO blocks form a shell of micelles. The transition of PNIPAm component shifts toward lower temperatures with increasing polymer concentration. 2D nuclear Overhauser effect spectroscopy spectra which can provide information on proton groups in close spatial contact (<0.5 nm) show an increase in intensity of cross-peaks between PEO protons and main chain CH and CH2 protons, and isopropyl CH protons of PNIPAm units after increasing the temperature from 292.7 to 301.6 K. The fact that this change occurs at temperature, which is still below the LCST transition of PNIPAm component evidences certain conformation changes in the PEO- b-PNIPAm block copolymer already in the pretransition region.
- Subjects
THERMORESPONSIVE polymers; COPOLYMERS; POLYETHYLENE oxide; NUCLEAR magnetic resonance; PROTONS
- Publication
Macromolecular Chemistry & Physics, 2016, Vol 217, Issue 12, p1370
- ISSN
1022-1352
- Publication type
Article
- DOI
10.1002/macp.201600025