INTERFACIAL AND OPTOELECTRONIC PROPERTIES OF GNP AND CNT/PVDF COMPOSITE SHEETS FOR ACOUSTIC ACTUATOR WITH NANO- AND HETERO- STRUCTURES

摘要

Nano- and hetero-structures of graphene nanoplatelet (GnP) and carbon nanotube (CNT) canrncontrol piezoelectric and optoelectronic properties for acoustic actuator, flexible transparentrnspeaker. Optimized conditions were obtained by obtaining the best dispersion and interfacialrndurability for the long-term use. Optical transmittance and electrical resistance were measuredrnfor GnP and CNT dip- and spraying coating on piezoelectric poly(vinylidene fluoride) (PVDF)rnsheets with elapsing time under cyclic loading. Uniform dip-coating was simply tried usingrnWilhelmy plate machine as well as spraying coating. The change in electrical resistance andrnoptical transmittance of coated layer was dependent upon the number of dip-coating, thernconcentration of nano-solutions. Electric properties of coated layers were measured using fourpointrnmethod and surface resistance was calculated by dual configuration method. Opticalrntransmittance of GnP and CNT coated PVDF sheet was evaluated using UV spectrum. Surfacernenergy and hydrophobicity were investigated by wettability test. As the elapsing time of cyclicrnloading passed and heating condition right after coating, the stability of surface resistance andrnthus comparative interfacial adhesion between coated layer and PVDF sheet was evaluated byrncomparing with the thermodynamic work of adhesion, Wa. As dip-coating number increased,rnsurface resistance of coated sheet decreased, whereas the transmittance decreased steadily due tornthicker nano-networking layer. Nano- and hetero-structural effects of GnP and CNT solution onrnthe optical and acoustic response were studied. The thin film transducers showed good acousticrnresponse over wide frequency ranges. Improved interfacial adhesion of was contributed tornincrease the sound pressure level (SPL) for acoustic actuator.