Pulsed laser deposition technic (PLD) was performed on both glass slab and hemp twill fabric in order to study the physico-chemical properties of the obtained thin films, as well as the physico-chemical processes and mechanisms developed under laser interaction with the natural biocomposite of oyster shells that led to obtaining the thin films of a certain chemical composition. Neither preliminary preparation nor chemical treatments were performed on the oyster shells used as targets in pursuing the purpose of the study to find new uses for such raw materials, and also to investigate the natural biocomposite behavior as a whole and by its components under laser irradiation and the results of the ablation and deposition process.
The investigation of the new procedure that we purpose herein was assisted and completed by COMSOL numerical simulation with finite element method (FEM) of heat effects induced by the laser beam on the composite structure where chitosan and calcium carbonate are considered, in thermal interaction, as being the main components of the oyster shell.
For oyster shell irradiation, the YG 981E/IR-10 laser system (Quantel, Les Ulis, France) in the installation ofFigure 1 was used with the following parameters: τ = 10 ns pulse width, λ = 532 nm wavelength, α = 45° incident angle, ν = 10 Hz pulse repetition time, r = 336 μm spot radius, F = 25 J/cm2 fluence, d = 3.5 cm distance between target and support.
The laser beam wavelength of 532 nm (in visible) was chosen because CaCO3, one of the main components in oyster shell [16 (link),18 (link)], does not absorb the laser beam of 532 nm [22 (link),23 ,24 ] as opposed to chitin, the component of interest for deposition and which will absorb the laser radiation of 532 nm [25 (link)]. Therefore, a high ablation rate of chitin was expected. The process is a selective extraction of one component of the composite material due to the different response of the components to the laser irradiation. Further, the 532 nm wavelength is preferred, being expected to be more suitable for a less aggressive interaction with the polymerized structures of the components in the oyster shell, same reason as reported by I. Cocean et al., 2019 and A. Cocean et al., 2021 on pulsed laser extraction and deposition of alpha-keratin [26 (link)] and of curcuminoids, respectively [27 (link)].
The analyses consisting of Fourier-transform infrared (FTIR) spectroscopy, laser-induced fluorescence (LIF) spectroscopy and Energy Dispersive X-ray coupled with Scanning Electron Microscope (SEM-EDS) were performed for the oyster shell used as target and for the deposited thin film. Atomic Force Microscopy (AFM) analysis provides information on the chitosan thin film morphology and topography. UV-Vis spectrum of the thin film obtained is also presented.
The investigation of the new procedure that we purpose herein was assisted and completed by COMSOL numerical simulation with finite element method (FEM) of heat effects induced by the laser beam on the composite structure where chitosan and calcium carbonate are considered, in thermal interaction, as being the main components of the oyster shell.
For oyster shell irradiation, the YG 981E/IR-10 laser system (Quantel, Les Ulis, France) in the installation of
The laser beam wavelength of 532 nm (in visible) was chosen because CaCO3, one of the main components in oyster shell [16 (link),18 (link)], does not absorb the laser beam of 532 nm [22 (link),23 ,24 ] as opposed to chitin, the component of interest for deposition and which will absorb the laser radiation of 532 nm [25 (link)]. Therefore, a high ablation rate of chitin was expected. The process is a selective extraction of one component of the composite material due to the different response of the components to the laser irradiation. Further, the 532 nm wavelength is preferred, being expected to be more suitable for a less aggressive interaction with the polymerized structures of the components in the oyster shell, same reason as reported by I. Cocean et al., 2019 and A. Cocean et al., 2021 on pulsed laser extraction and deposition of alpha-keratin [26 (link)] and of curcuminoids, respectively [27 (link)].
The analyses consisting of Fourier-transform infrared (FTIR) spectroscopy, laser-induced fluorescence (LIF) spectroscopy and Energy Dispersive X-ray coupled with Scanning Electron Microscope (SEM-EDS) were performed for the oyster shell used as target and for the deposited thin film. Atomic Force Microscopy (AFM) analysis provides information on the chitosan thin film morphology and topography. UV-Vis spectrum of the thin film obtained is also presented.
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