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High-Frequency Dynamics in PEG+H2O System

This study explores the high-frequency dynamics and visco-elastic properties of the PEG+H2O system using Brillouin light scattering. The results provide insights into the relaxation processes and temperature analysis of the system.

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High-Frequency Dynamics in PEG+H2O System

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  1. High-Frequency Dynamics in PEG+H2O System Mikołaj Pochylski Adam Mickiewicz University (UAM) Department of Physics, Poznań, Poland

  2. Poznań

  3. Poznań

  4. Adam Mickiewicz University • Adam Mickiewicz University in numbers: • 400 years of tradition • 14 departments • 5000 employees (2700 academic teachers) • 55 000 students

  5. University Campus - Department of Physics

  6. Outline • PolyEthylene Glycol – PEG • Brillouin Light Scattering • Relaxation process • – Visco–elasticity • –Relaxation functions • Results for PEG+H2O system: • – Temperature analysis • – Frequency analysis • – Comparison with dielectric results

  7. PolyEthylene Glycol - PEG OH-(CH2-CH2-O)n-H PEG600(n=13)

  8. PolyEthylene Glycol - PEG • General properties: • Non-toxic, flexible,hydrophilic (amphiphilic) • Application examples: • Separation, purification and fusion of biomolecules and cells, • Hydrophilic moiety in nonionic surfactants, • Matrix for ion conducting polymer electrolytes, • Coating of implants and ship hulls • ... Industry fields: Biomedical, Pharmaceutical, Cosmetics, Textile, Paints, Food ...

  9. PolyEthylene Glycol - PEG hydroxyl group ether group

  10. – density fluctuations Dynamic structure factor (shape of the spectrum) – Dielectric constant fluctuations Light scattering

  11. Light scattering Linearized hydrodynamic equations for viscous fluid FT

  12. Spectrum of scattered light Intensity Frequency

  13. Brillouin Light Scattering Brillouin Frequency Shift

  14. Acoustical parameters: Hypersound velocity - vB Normalized attenuation coefficient - /f2 Brillouin Light Scattering Brillouin Shift: (velocity of soundwave) Scattering Wave Vector: Brillouin Linewidth (HWHM): (attenuation of soundwave) Kinematic longitudinal viscosity Brillouin Spectroscopy: extension of Ultrasonic Spectroscopy for GHz frequencies

  15. Brillouin Light Scattering Longitudinal Modulus, M: Describes mechanical response of a medium (induced stress) subjected to longitudinal deformation

  16. Acoustical parameters: Hypersound velocity - vB Normalized attenuation coefficient - /f2 Brillouin Light Scattering Complex longitudinal modulus components: Accumulation modulus – M’ Loss modulus – M”

  17. Fabry-Perot Spectrometer

  18. Brillouin Light Scattering

  19. – Relaxation time Visco-elasticity

  20. Peak condition Relaxation Debye relaxation function

  21. B , B vB, /f2 M’ , M” Results – PEG600 Brillouin spectra for pure PEG600 at different temperatures Normalized intensity Frequency shift [GHz]

  22. Debye relaxation function Temeprature dependence of relaxation time: • Vogel-Fulcher-Tamman • Arrhenius Maisano, G., et al.,Mol. Phys. 1993, 78, 421 Results – PEG600

  23. Relaxation in complex liquids Arrhenius Vogel-Fulcher-Tamman

  24. Results Temperature experiment for PEG400 solutions

  25. Havriliak-Negami Debye Cole-Cole Cole-Davidson Results Temperature experiment for PEG400 solutions Havriliak-Negami function

  26. Results Temperature experiment for PEG400 solutions Cole-Cole function Vogel-Fulcher-Tamman

  27. Brillouin Light Scattering Full Spectrum Analysis Dynamic structure factor Havriliak-Negami function

  28. Poor quality of fit: presence of the distribution of relaxation times • More complicated relaxation function is needed Full Spectrum Analysis – PEG600 Debye relaxation

  29. Full Spectrum Analysis – PEG600 Cole-Davidson relaxation function

  30. Full Spectrum Analysis – PEG400

  31. Havriliak-Negami Debye relaxation Full Spectrum Analysis – PEG400 • Modulus expressed in terms of the Longitudinal Compliance, J(Havriliak-Negami function) •  and  taken directly from dielectric experiment T. Sato, et al.,J. Chem. Phys. 1998, 108, 4138

  32. Relaxation times vs PEG concentration comparison with Dielectric Spectroscopy results [1] M. Pochylski et al., J.Phys. Chem. B2006, 110, 20533 [2] T. Sato et al, J.Chem.Phys.1998, 108, 4138 [3] N. Shinyashiki et al, J.Chem.Phys.1990, 93, 760 [4] C.H. Wang et al., J. Non-Cryst. Solids1991, 131, 970. [5] T. Noudou et al., Jpn. J. Appl. Phys.1996, 35, 2944.

  33. PEG282, x’=0.42 DVFT = 7.6 PEG400, x’=0.50 DVFT = 7.2 Relaxation times vs Temperature comparison with Dielectric Spectroscopy results [1] Murthy, S.S.N. et al., J. Phys. Chem. B 2000, 104, 6955 [2] Sudo, S. et al., J. Chem. Phys. 2004, 121, 7332

  34. Thanks for Your Attention !

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