Interpenetrated PNIPAM-polythiophene microgels for nitro aromatic compound detection

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Thermally responsive polymers like PNIPAM undergo volume phase transitions with temperature.
• Fluorescent polymers, such as PTEBS, can have their optical properties modulated by their environment.
• Developing smart materials with tunable optical properties is crucial for advanced sensing applications.

Purpose of the Study:

• To synthesize and characterize novel fluorescent microgels combining PNIPAM and PTEBS.
• To investigate the effect of temperature-induced volume phase transitions on the microgels' photoluminescence.
• To explore the potential of these microgels as reusable microsensors for nitroaromatic compounds.

Main Methods:

• Facile and reproducible synthesis of interpenetrated PNIPAM-PTEBS microgels (<700 nm).
• Temperature-dependent photoluminescence (PL) spectroscopy to monitor optical property changes.
• Time-resolved fluorescence and neutron scattering measurements to probe structural and dynamic changes.

Main Results:

• Microgel PL intensity decreased above the PNIPAM low critical solution temperature (LCST).
• Cross-linking and system rigidity influenced PTEBS fluorescence decay time in swollen and collapsed states.
• PNIPAM matrix interactions above LCST hindered pi-pi interactions, affecting PTEBS emission.

Conclusions:

• PNIPAM-PTEBS microgels offer tunable fluorescence based on temperature-induced phase transitions.
• The observed changes in PL are linked to microgel structure and polymer chain interactions.
• These microgels show promise for developing reusable fluorescent microsensors for detecting nitroaromatic compounds via PL quenching.