Dynamic Surface Modification of Metal-Organic Framework Nanoparticles via Alkoxyamine Functional Groups

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• External surface engineering of metal-organic framework nanoparticles (MOF NPs) is crucial for enhancing chemical and colloidal stability.
• Current MOF surface modification methods often lack precise control over polymer density and dynamic surface changes.

Purpose of the Study:

• To introduce a general approach for precise and dynamic surface modification of MOF NPs using alkoxyamines.
• To demonstrate the versatility of alkoxyamines for initiating polymer growth and enabling dynamic molecular attachment on MOF NP surfaces.

Main Methods:

• Covalent modification of MOF NPs using alkoxyamines as initiators for nitroxide-mediated polymerization (NMP).
• Dynamic attachment of small molecules via nitroxide exchange reaction (NER).
• Characterization using time-of-flight secondary ion mass spectrometry (ToF-SIMS), size exclusion chromatography (SEC), nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) spectroscopy.

Main Results:

• Successful surface modification and polymerization of MOF NPs confirmed by ToF-SIMS, SEC, and NMR.
• Functionalized MOF NPs showed high suspension stability, good dispersibility, and retained chemical integrity and crystalline structure.
• EPR studies confirmed dynamic exchange of nitroxide species via NER and enabled sensitive quantification of surface modification.

Conclusions:

• Alkoxyamines provide a versatile and precise method for dynamic surface modification of MOF NPs.
• This approach allows tailoring MOF NP properties for diverse applications, including drug delivery and mixed matrix membranes.