Preparation And Application Of Hydrotalcite-based Composite Film With Room Temperature Phosphorescencethe

The nanoparticle/polymer composite materials have received wide attention in the field of advanced construction,transportation,biomedical implants,and military defense because of their high strength-to-weight ratio(specific strength)and high toughness(flaw tolerance).However,the construction of high-performance nanoparticle/polymer composite materials still face technical challenges:(1)how to transfer the intrinsic extraordinary performance of individual nanoplatelets into highly ordered macroscale bulk materials;(2)how to obtain a strong interface bonding between polymer and nanoplatelet filler;(3)the last and most important factor is that the interaction mechanism between nanoplatelet filler and polymer at the multiscale is insufficiently understood,inhibiting the development and application of the advanced nanoparticle/polymer composite materials.Based on the luminescent properties of carbon dots(CD),the confinement effect and rigidity of LDH,and the good film-forming properties of polyvinyl alcohol,the composite films with room temperature phosphorescence were prepared.The interaction and luminescence principle were systematically studied.The application of the film in gas barrier and sensing is also discussed.The main contents of the dissertation are as follows:1.Two kinds of illuminants with different degrees of conjugation were selected as carbon sources,LDH was intercalated by ion exchange method,and CD/LDH composites were constructed after hydrothermal treatment.The LDH-based composite film with superior fluorescence and room temperature phosphorescence properties was prepared by solvent evaporation method.The precursors of the luminescent molecules are different,and the structure of carbon dots are also different,which will cause changes in optical performance.The difference in interaction forces leads to respond differently of the film to external pressure.At the same time,The CD-LDH composite film can be used not only in LED devices,but also can be used in pressure sensing because of its fast response,high sensitivity,repeatability,stability and large working range.2.Solvent evaporation method has problems such as non-fine regulation and uneven dispersion of nanoparticles.In order to obtain a uniform and orderly composite film,we used the methods of flow-induced assembly to make flexible,large-size continuous,transparent and highly oriented nanoparticle/polymer composite film.During the flow-induced orientation,nanoplatelet and polymer can look forward to coassembling in one step to form a highly ordered layered structure with dozens of layers.To explore the effect of multi scale structure on property,CD are introduced to light up the inorganic nanoplatelet.By fixing and confining CDs in a rigid environment,the CD-LDH-based composite film shows excellent dual emission characteristics,which can be used to evaluate gas barrier,humidity,and temperature with direct visualization,high sensitivity,and easy to operation.