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NMR and DSC study of temperature-induced phase transition in aqueous solutions of poly(N-isopropylmethacrylamide-co-acrylamide) copolymers
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SYSNO ASEP 0382101 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title NMR and DSC study of temperature-induced phase transition in aqueous solutions of poly(N-isopropylmethacrylamide-co-acrylamide) copolymers Author(s) Šťastná, J. (CZ)
Hanyková, L. (CZ)
Spěváček, Jiří (UMCH-V) RID, ORCIDSource Title Colloid and Polymer Science - ISSN 0303-402X
Roč. 290, č. 17 (2012), s. 1811-1817Number of pages 7 s. Language eng - English Country DE - Germany Keywords temperature induced phase transition ; thermosensitive copolymer ; poly(N-isopropylmethacrylamide-co-acrylamide) Subject RIV CD - Macromolecular Chemistry R&D Projects GA202/09/1281 GA ČR - Czech Science Foundation (CSF) Institutional support UMCH-V - RVO:61389013 CEZ AV0Z40500505 - UMCH-V (2005-2011) UT WOS 000310319000011 DOI https://doi.org/10.1007/s00396-012-2701-3 Annotation Combination of 1H NMR spectroscopy and differential scanning calorimetry (DSC) was used to investigate temperature-induced phase transition in D2O solutions of poly(N-isopropylmethacrylamide-co-acrylamide) random copolymers. Both the NMR and DSC data showed dependence on the acrylamide (AAm) content in the copolymer; with increasing AAm content, the phase transition is shifted to higher temperatures, and both phase-separated fractions determined by NMR and change of the enthalpy determined by DSC decrease faster than the content of thermosensitive N-isopropylmethacrylamide (NIPMAm) units in the copolymer. NMR data were used to construct van't Hoff plots, and changes of the enthalpy ΔH and entropy ΔS, characterizing the phase transition, were determined. As it follows from comparison of NMR and DSC thermodynamical parameters (ΔH values), the size of the cooperative units (domains), undergoing the transition as a whole, decreases with increasing AAm content in the copolymer since the NIPMAm collapsed domains are separated by regions with hydrated AAm and surrounding NIPMAm sequences. Workplace Institute of Macromolecular Chemistry Contact Eva Čechová, cechova@imc.cas.cz ; Tel.: 296 809 358 Year of Publishing 2013
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