Solid-state dendrimer sensors: probing the diffusion of an explosive analogue using neutron reflectometry

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Solid-state sensors rely on analyte sequestration into thin films for detection.
• Oxidative luminescence quenching is a key mechanism for analyte detection in such sensors.

Purpose of the Study:

• To investigate the rapid and reversible detection of p-nitrotoluene using dendrimer thin films.
• To understand the analyte adsorption process within dendrimer films via combined photoluminescence and neutron reflectometry.

Main Methods:

• Fabrication and characterization of thin and thick dendrimer films.
• Measurement of photoluminescence (PL) quenching upon exposure to p-nitrotoluene.
• Neutron reflectometry to analyze film swelling and structural changes during analyte adsorption and desorption.

Main Results:

• Both thin (230 +/- 30 A) and thick (750 +/- 50 A) dendrimer films achieved ~90% PL quenching of p-nitrotoluene within 4 seconds.
• Analyte adsorption caused reversible swelling of the dendrimer films by approximately 4%.
• Complete restoration of PL and film thickness upon analyte removal confirmed the sensing process's reversibility.

Conclusions:

• Dendrimer thin films offer a highly efficient and reversible platform for p-nitrotoluene detection via oxidative luminescence quenching.
• The observed reversible swelling and PL quenching highlight the dynamic interaction between the analyte and the dendrimer matrix.
• These findings present a significant advancement over traditional luminescent polymer films for sensing applications.