Fluorescent Nanocomposite Based on PVA Polymer Dots

Currently, fluorescent polymer dots (PDs) draw much attention these years in the fields of bioimaging and sensor due to their high fluorescence efficiency and extraordinary light-gathering capability. However, the present PDs are most conjugated polymer dots derived from conjugated polymer assembly. They preserve the advantages of conjugated polymer dots. Moreover, they are more stable than conjugated polymer and can be further functionalized for practical applications. The PDs in this article are prepared from non-conjugated linear polymer instead of conjugated polymer. Linear polymer is a kind of macromolecules composed of repeating non-conjugated structural units, such as polyethylene glycol (PEG), polysaccharides. These polymers show no fluorescence due to lack of photoluminescent centre. As a result, it is fancy to obtain fluorescent materials from this kind of simple polymers. Using carbonization method, photoluminescent polymer dots were prepared by moderately hydrothermal treating polyvinyl alcohol (PVA). PDs contain not only the fluorescent carbon center, but also the connected polymer chains. It's highly interesting to apply these PDs to polymer based fields using the outstanding properties of polymer chains. In this paper, derived from the fluorescent property and connected polymer chains of PDs, we investigated the functional nanocomposite based on PDs. Firstly, the polyvinyl alcohol (PVA)/PDs nanocomposite films were prepared (PDs was synthesized by carbonization of PVA). The nanocomposite films hold the fluorescent properties of PDs while it's also facile to be processed like the linear PVA, for example, nanocomposite films were prepared based on PDs, the proportion of PDs and PVA can be tuned as requirement from 0, 20%, 40%, 60%, 80%, 100%. The nanocomposite films have multi-color emission properties using different excitations due to the excitation-dependent behavior of PDs. Furthermore, other nanocomposites based on PDs were investigated such as PDs/water-solubility polymers, PDs/graphene quantum dots (GQDs) and PDs/semiconductor quantum dots. These nanocomposites have di-fluorescence property at the same excitation and could be used at sensor fields.