Chain dynamics in microgels : poly(N-vinylcaprolactam-co-N-vinylpyrrolidone) microgels as examples
Microgels are highly swollen colloids built up of flexible cross-linked chains. We studied the static and dynamic light scattering (LS) behavior of thermosensitive microgels based on N-vinylcaprolactam and N-vinylpyrrolidone prepared by precipitation copolymerization in H2O (CP-1) and D2O (CP-2). St...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1991. - 23(2007), 2 vom: 16. Jan., Seite 776-84 |
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| Weitere Verfasser: | , , |
| Format: | Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2007
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article |
| Zusammenfassung: | Microgels are highly swollen colloids built up of flexible cross-linked chains. We studied the static and dynamic light scattering (LS) behavior of thermosensitive microgels based on N-vinylcaprolactam and N-vinylpyrrolidone prepared by precipitation copolymerization in H2O (CP-1) and D2O (CP-2). Striking differences in behavior were observed in the two solvents. In both cases the angular dependence of static LS could reasonably well be described by a soft sphere model (J. Polym. Sci., Polym. Phys. Ed. 1982, 20, 157) with small deviations at large qRg. At temperatures larger than the collapse temperatures, the CP-1 sample in water started to aggregate whereas the CP-2 sample in D2O showed no association and developed the expected change toward hard sphere behavior. Dynamic LS permitted the determination of internal or segmental mobility. A remarkable shift toward large qRg was found for CP-1 compared to the behavior of linear chains. The dynamic behavior is clearly displayed in a plot of Gamma*(q) = (Gamma1(q)/q3)(eta0/kT), with Gamma1(q) the first cumulant of the field time correlation function and the common meaning of the other parameters. A long range of hard sphere behavior indicated the suppression of internal modes, but at large qRg the swollen microgel CP-1 in water displayed internal motions with a spectrum similar to that of Zimm relaxations. No internal mobility could be detected with the CP-2 sample in D2O. The behavior is in agreement with observations in the literature. The differences in the two similar solvents were attributed to the poorer solvent quality of D2O |
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| Beschreibung: | Date Completed 17.07.2007 Date Revised 09.01.2007 published: Print Citation Status PubMed-not-MEDLINE |
| ISSN: | 0743-7463 |