Molecular dynamics and interactions of aqueous and dichloromethane solutions of polyvinylpyrrolidone

Hideaki Shirota, Ed Castner

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

We have investigated the dynamics of polyvinylpyrrolidone solutions (PVP, M w= 10 000) on time scales from 20 fs to 42 ps using femtosecond optically heterodyne-detected Raman-induced Kerr effect spectroscopy. To compare the dynamics of polymer solutions with those of the analogous monomer, we also characterized solutions of 1-ethyl-2-pyrrolidone (EP). Dynamics of both PVP and EP solutions have been characterized for sample concentrations of 6.4, 12.7, 24.5, 33.3, and 40.7 wt %. The longest time scale relaxations observed in the Kerr transients for these solutions occur on the picosecond time scale and are best fit to triexponential functions. The intermediate and slow relaxation time constants for PVP and EP solutions are concentration dependent. The time constants for the PVP solutions are not consistent with the predictions of hydrodynamic models, while the analogous time constants for the EP solutions do display hydrodynamic scaling. The predominant relaxation of the polymer is assigned to reorientations of the pyrrolidone side group or torsional motions of the constitutional repeat unit, with additional relaxation pathways including hydrogen bond reorganization in aqueous solution and segmental motion of multiple repeat units. The vibrational dynamics of PVP and EP solutions occur on the femtosecond time scale. These dynamics are analyzed with a focus on the additional degrees of freedom experienced by EP relative to PVP that result from the absence of the tether from the pyrrolidone group on the main chain backbone. The intermolecular Kerr spectra of PVP in H 2O and CH 2Cl 2 differ because H 2O can donate a hydrogen bond to the carbonyl acceptor group on the pyrrolidone ring, while CH 2Cl 2 cannot.

Original languageEnglish
Article number034904
JournalJournal of Chemical Physics
Volume125
Issue number3
DOIs
Publication statusPublished - 2006

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Povidone
Molecular interactions
Methylene Chloride
molecular interactions
Molecular dynamics
molecular dynamics
aqueous solutions
Pyrrolidinones
time constant
Hydrogen bonds
Hydrodynamics
hydrodynamics
methylidyne
hydrogen bonds
polymers
Polymer solutions
Kerr effects
Relaxation time
retraining
2-pyrrolidone

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Molecular dynamics and interactions of aqueous and dichloromethane solutions of polyvinylpyrrolidone. / Shirota, Hideaki; Castner, Ed.

In: Journal of Chemical Physics, Vol. 125, No. 3, 034904, 2006.

Research output: Contribution to journalArticle

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