Sökning: onr:"swepub:oai:DiVA.org:kth-5533" >
Kinetics of demixin...
Kinetics of demixing and remixing transitions in aqueous solutions of poly(N-isopropylacrylamide) : A temperature-jump H-1 NMR study
-
- Yushmanov, Pavel (författare)
- KTH,Centrum för Industriell NMR-teknik
-
- Furó, István (författare)
- KTH,Centrum för Industriell NMR-teknik
-
Iliopoulos, Ilias (författare)
-
(creator_code:org_t)
- Wiley, 2006
- 2006
- Engelska.
-
Ingår i: Macromolecular Chemistry and Physics. - : Wiley. - 1022-1352 .- 1521-3935. ; 207:21, s. 1972-1979
- Relaterad länk:
-
https://urn.kb.se/re...
-
visa fler...
-
https://doi.org/10.1...
-
visa färre...
Abstract
Ämnesord
Stäng
- The time course of the coil-to-globule collapse and intermolecular aggregation of poly(N-isopropylacrylamide) in aqueous solution upon exceeding the lower critical solution temperature (LCST) are investigated by temperature-jump 1H NMR spectroscopy. After the temperature jump, we record the time dependences of (i) the mobile fraction of the polymer chain as revealed by the intensity of the liquid-like NMR signal, (ii) the local mobility of those chains as revealed by the transverse relaxation time T2, and (iii) their self-diffusion coefficient D. The same data are also reported at their temperature-dependent long-time limits. The results suggest a sudden, faster than one second, collapse and intermolecular aggregation into globules and a slower reorganization/redistribution of the individual chains among and within the globular and mobile states. We found that all molecular changes are reversible if the temperature remains less than ca. 6-8 K above the LCST for less than a few minutes; under those conditions, experiments upon sudden temperature quench below the LCST show that the aggregates disintegrate and swell into coils in less than a few seconds.
Ämnesord
- NATURVETENSKAP -- Kemi -- Fysikalisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Physical Chemistry (hsv//eng)
Nyckelord
- Aggregation
- Miscibility
- NMR
- Temperature jump
- Turbidity
- Physical chemistry
- Fysikalisk kemi
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
Hitta via bibliotek
Till lärosätets databas