TY - JOUR
AU - Koplitz, Brent
AB - There has been an explosive interest in the technique of laser assisted deposition of polymer nano-composite filmsexploiting the matrix assisted pulsed laser evaporation (MAPLE) with regard to the polymer host as can be judged formrecent publications.1-4 In MAPLE, a frozen solution of a polymer in a relatively volatile solvent is used as a laser target.The solvent and concentration are selected so that first, the polymer of interest can dissolve to form a dilute, particulatefree solution, second, the majority of the laser energy is initially absorbed by the solvent molecules and not by the solutemolecules, and third, there is no photochemical reaction between the solvent and the solute. The light-materialinteraction in MAPLE can be described as a photothermal process. The photon energy absorbed by the solvent isconverted to thermal energy that causes the polymer to be heated but the solvent to vaporize. As the surface solventmolecules are evaporated into the gas phase, polymer molecules are exposed at the gas-target matrix interface. Thepolymer molecules attain sufficient kinetic energy through collective collisions with the evaporating solvent molecules,to be transferred into the gas phase. By careful optimization of the MAPLE deposition conditions (laser wavelength,repetition rate, solvent type, concentration, temperature, and background gas and gas pressure), this process can occurwithout any significant polymer decomposition. The MAPLE process proceeds layer-by-layer, depleting the target ofsolvent and polymer in the same concentration as the starting matrix. When a substrate is positioned directly in the pathof the plume, a coating starts to form from the evaporated polymer molecules, while the volatile solvent molecules areevacuated by the pump from the deposition chamber. In case of fabrication of polymer nanocomposites, MAPLE targetsare usually prepared as nano-colloids of the additives of interest in the initial polymer solutions.Mixing the components of different nature, organic polymers and inorganic dopants, in the same target at a certainproportion and exposing them to the same laser beam not necessarily brings good quality nano-composite films. Thelaser pulse energy and wavelength cannot be optimized for each component individually. Also, the mixing proportion inthe composite film is dictated by the initial proportion of the target and thus cannot be changed in the process. Theselimitations were removed in the recently proposed method of multi-beam and multi-target deposition (in its doublebeam/dual-target variation) using a MAPLE polymer target and one inorganic target, each being concurrently exposed tolaser beams of different wavelengths.5-14 Using the method, nano-composite films of polymer poly(methyl methacrylate)known as PMMA doped with a rare earth (RE) inorganic upconversion phosphor compounds were prepared. Also, anano-composite film of thermoelectric film of inorganic aluminum-doped ZnO known as AZO was impregnated withPMMA nano-fillers with the purpose of improving electrical conductivity and thermoelectric performance.10, 14 Thepolymer target was a frozen (to a temperature of liquid nitrogen) PMMA solution in chlorobenzene exposed to a 1064-nm laser beam from a Q-switched Nd:YAG pulsed laser. The inorganic targets were the pellets made of the compressedmicro-powders of highly efficient RE-doped NaYF4 or the sintered powder of AZO concurrently ablated with the
TI - Organic-inorganic nano-composite films for photonic applications made by multi-beam multi-target pulsed laser deposition with remote control of the plume directions
JF - Proceedings of SPIE
DO - 10.1117/12.2237538
DA - 2016-09-07
UR - https://www.deepdyve.com/lp/spie/organic-inorganic-nano-composite-films-for-photonic-applications-made-feKr7zxw3F
SP - 995802
EP - 995802-15
VL - 9958
IS - 
DP - DeepDyve
ER -