0382101 - ÚMCH 2013 RIV DE eng J - Journal Article
Šťastná, J. - Hanyková, L. - Spěváček, Jiří
NMR and DSC study of temperature-induced phase transition in aqueous solutions of poly(N-isopropylmethacrylamide-co-acrylamide) copolymers.
Colloid and Polymer Science. Roč. 290, č. 17 (2012), s. 1811-1817. ISSN 0303-402X. E-ISSN 1435-1536
R&D Projects: GA ČR GA202/09/1281
Institutional research plan: CEZ:AV0Z40500505
Institutional support: RVO:61389013
Keywords : temperature induced phase transition * thermosensitive copolymer * poly(N-isopropylmethacrylamide-co-acrylamide)
Subject RIV: CD - Macromolecular Chemistry
Impact factor: 2.161, year: 2012 ; AIS: 0.474, rok: 2012
DOI: https://doi.org/10.1007/s00396-012-2701-3

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.
Permanent Link: http://hdl.handle.net/11104/0212424