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Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Molecular mobility and transport in polymer membranes and polyelectrolyte multilayers
Alexandr Sagidullin1, Jochen Meier-Haack, Ulrich Scheler
1Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, D-01069 Dresden, Germany.
Magnetic Resonance Imaging
|May 1, 2007
Summary
Polyelectrolyte multilayers offer tailored membranes for pervaporation, reducing fouling and enhancing selectivity. Pulsed field gradient nuclear magnetic resonance revealed selective interactions within these advanced polymer systems.
Area of Science:
- Materials Science
- Polymer Chemistry
- Separation Science
Background:
- Polyelectrolyte multilayers (PEMs) are fabricated using layer-by-layer assembly.
- PEMs enable precise control over surface charge and hydrophobicity for membrane applications.
- These membranes are utilized in pervaporation processes, offering improved selectivity and reduced fouling.
Purpose of the Study:
- To investigate the diffusion behavior of probe molecules within polyelectrolyte multilayer membranes.
- To characterize the pore structure and molecular interactions in PEMs using advanced techniques.
- To correlate diffusion properties with the selective performance of PEMs in pervaporation.
Main Methods:
- Fabrication of polyelectrolyte multilayers via the layer-by-layer technique.
- Pulsed field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy to study molecular diffusion.
- Analysis of diffusion coefficients and propagators for probe molecules (e.g., propanol, water mixtures).
Main Results:
- PFG-NMR successfully investigated molecular diffusion in polymer systems.
- Diffusion analysis in porous poly(amide) correlated with electron microscopy pore size (4 microm).
- Diffusion of propanol and propanol-water mixtures into PEMs indicated selective interactions, with no equivalent pores observed via microscopy.
Conclusions:
- Polyelectrolyte multilayers provide tunable surface properties for selective pervaporation membranes.
- PFG-NMR is a valuable tool for probing molecular interactions and diffusion within complex polymer structures.
- The study suggests selective interactions between probe molecules and the polyelectrolyte system, contributing to membrane performance.
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