A 129Xe NMR study on an ionomeric polymer blend system.
The morphology of an ionomeric polymer blend consisting of an amino-silicone copolymer and zinc neutralized sulfonated polystyrene (ZnSPS) has been studied using proton spin diffusion and small angle X-ray scattering (SAXS). The extent of reaction between the two components in the blend was monitored by 13C CP MAS spectroscopy. All three types of experiment point to domain sizes in the nanometer range. 129Xe NMR was used to study exchange by translational diffusion between domains. A single xenon resonance was detected in temperatures ranging from 25 degrees C to -90 degrees C, and the chemical shift followed a weighted average of the isolated polymer shifts consistent with the small domain sizes. Pulse field gradient 129Xe NMR was used to determine the effective diffusion constants in the amino silicone starting material and the blend. The diffusion constant of xenon in poly(styrene) is known, allowing for comparison of the predictions of effective diffusion constants in the blend based on the values in the constituents of the blend. Simple two-site exchange equations incorrectly predict that diffusion in the blend would be dominated by the constituent with slow diffusion. The blend diffusion constant is close to the value of the amino silicone or the constituent with fast diffusion which is correctly predicted for a rapid exchange solution of the diffusion equation.
Yang
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Chemistry Department, Clark University, Worcester, MA 01610, USA.
Wen
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Jones
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Inglefield
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D004058:Diffusion; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D011137:Polystyrenes / Q000737:chemistry*; D012542:Scattering, Radiation; D012828:Silicones / Q000737:chemistry*; D014979:Xenon Isotopes
D011137:Polystyrenes; D012828:Silicones; D014979:Xenon Isotopes