Nanostructure of Materials Determined by Relayed Paramagnetic Relaxation Enhancement

Area of Science:

• Materials Science
• Polymer Chemistry
• Analytical Chemistry

Background:

• Material properties are significantly affected by particle and domain sizes.
• Accurate measurement of nanoscale dimensions is critical in fields like pharmaceuticals and materials science.
• Existing methods may have limitations in resolving specific domain sizes within complex mixtures.

Purpose of the Study:

• To introduce and validate a novel nuclear magnetic resonance (NMR) approach for determining nanoscale lengths.
• To apply this NMR technique to measure domain sizes in multicomponent polymer systems.
• To assess the utility of this method in pharmaceutical controlled-release formulations.

Main Methods:

• Utilized paramagnetic relaxation enhancement (PRE) relayed by spin diffusion (SD) via NMR.
• Selectively doped one component of a polymer mixture with a paramagnetic center.
• Measured domain sizes in a second, non-doped component of the mixture.

Main Results:

• Successfully determined lengths in the nanometer to micrometer range.
• Quantified domain sizes in ethyl cellulose/hydroxypropyl cellulose film coatings.
• Measured particle sizes within the range of approximately 50 to 200 nm.

Conclusions:

• The PRE-relayed by SD NMR method is effective for measuring nanoscale domain sizes.
• This technique provides valuable insights into the microstructure of polymer blends.
• The approach is applicable to pharmaceutical formulations, aiding in the design of controlled-release systems.