Preparation And Characterization Of Multistimuli-Responsive Photoluminescent Nanocomposites Of Silver Nanoclusters With Hyperbranched Polyethylenimine Derivatives

Trimethylacetamide (TMA) groups were introduced to the terminals of hyperbranched polyethylenimine (PEI) through the amidation reaction between PEI and trimethylacetic anhydride. The hyperbranched polyethylenimine with a certain number of trimethylacetamide groups (PEI-TMA) was thermoresponsive. Furthermore, silver nanoclusters (AgNCs) functionalized with PEI-TMA were prepared using a facile, one-pot reaction under mild conditions. The influence of the preparation conditions, including the pH value in the mixture of PEI-TMA and Ag+ and the Ag+/PEI-TMA feed ratio, on the photoluminescence properties of the obtained nanocomposite of AgNCs and PEI-TMA (AgNC-PEI-TMA) was studied. The obtained AgNC-PEI-TMA nanocomposite was characterized by transmission electron microscopy, dynamic light scattering and zeta potential measurements, verifying the formation of the nanocomposite. AgNC-PEI-TMA in water was not only thermoresponsive, but also responded to other stimuli, including pH, inorganic salts, and loaded organic guest, which was similar to the stabilizer PEI-TMA. The obtained AgNC-PEI-TMA nanocomposite was photoluminescent, and its maximum emission intensity was stronger than AgNC-PEI. Its emission intensity was influenced negligibly by pH (8-11), traditional salting-out anions (Cl- and SO42-), and the relatively polar aspirin guest. However, the traditional salting-in I- anion could quench its fluorescence a little.