Fluorescence microscopy and photodielectric characterization studies of the composite films of polyvinyl alcohol and tryptophan functionalized silver nanoparticles

Fluorescent nanocomposite films were prepared by solution mixing of polyvinyl alcohol (PVA) and tryptophan functionalized silver (AgTrp) nanoparticles. Synchrotron excitation deep-ultraviolet (DUV) fluorescence imaging was used to follow the distribution of AgTrp nanoparticles within the polymer matrix. Pronounced growth of dendrite-like structures in the presence of AgTrp nanoparticles was confirmed by bright field and fluorescence imaging as well as with atomic force microscopies. Both tryptophan and AgTrp nanoparticles influence thermal properties of the matrix. Differential scanning calorimetry measurements showed that they reduce crystallinity and significantly increase the glass transition temperature of PVA (in the case of PVA-AgTrp film the T-g increases by similar to 20 degrees C). Dielectric properties of the films were studied under two different conditions (dark and illumination). The illumination with 250 nm light induces a significant increase in conductance of the PVA-AgTrp nanocomposite. The relative changes, with respect to the conductance measured in the dark, were almost similar to 200%.

Automated summary

In this study, fluorescent nanocomposite films were prepared by solution mixing of polyvinyl alcohol (PVA) and tryptophan functionalized silver (AgTrp) nanoparticles. The distribution of AgTrp nanoparticles within the polymer matrix was tracked using synchrotron excitation deep-ultraviolet fluorescence imaging. The presence of AgTrp nanoparticles resulted in the pronounced growth of dendrite-like structures, which was confirmed by various imaging techniques. Both tryptophan and AgTrp nanoparticles affected the thermal properties of the matrix, reducing crystallinity and increasing the glass transition temperature of PVA. Furthermore, the films showed a significant increase in conductance under illumination with 250 nm light, with the relative changes reaching almost 200% compared to the dark condition.