Alteration of optical and morphological properties of polycarbonate illuminated by visible/IR laser beams (original) (raw)
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The Effect of Laser Radiation on the Surface Properties of Polycarbonate Films
2004
Surface modification can be done using various methods. For Polymeric surface, one of the most important methods is the laser treatment. At this method, we can exactly control the type and quality of surface treatment. Special wavelength of laser beam can be selectively absorbed by special bond. Laser absorbed energy can change chemical structure of selective bonds and so physical properties of polymer surface. At present work, CO2 and Nd:YAG Lasers were used to modify surface of Polycarbonate (PC) films in order to increase their biocompatibility of films. After laser irradiation in air, some changing in chemical and physical properties of the irradiated films took place. The irradiated film was characterized by using the light microscope, scanning electron microscopy (SEM) and contact angle measurements. The effect of pulse number on the surface properties was also investigated. To examine final biocompatibility of PC films cell culture growth tests on the treated surface was also...
Hydrophilicity and morphological investigation of polycarbonate irradiated by ArF excimer laser
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007
Lasers are used to modify polymeric materials. In this work, a number of polycarbonate (PC) pieces were exposed by ArF excimer laser, 193 nm, at various UV doses from 10 to 100 J/cm 2 with 50-500 mJ/pulse at 10 Hz pulse repetition rate. Morphology of PC has been investigated by scanning electron microscope (SEM) at three regimes pre-ablation, slow and fast ablation. SEM identifies that the conical defects are created on the polymer surface to grow opposite to the direction of laser irradiation. It increases the superficial absorptivity of the material dependent on the ArF laser induced conical microstructure geometry. The contact angle measurement was performed here, in order to determine the hydrophilicity of the irradiated polymer at various coherent doses. It is shown that the contact angle of PC samples which are exposed to the ArF laser significantly alters with UV dose below 7 J/cm 2 .
SEM STUDY OF CONICAL STRUCTURES ON POLYCARBONATE SURFACE INDUCED BY ArF LASER
The surface modification of polycarbonate (PC) by 193 nm ArF laser radiation with fluences of 24–62 mJ/cm 2 and pulse numbers of 1–100 is reported. Noticeable changes including microcone structures on irradiated surfaces have been observed through scanning electron microscope (SEM). It has been shown that the geometrical characteristics (apex angle and base diameter) of the microcones depend on the incident laser fluence. With the increase of the radiation fluence the microcone apexes become sharper, however, their base diameters increase. Поверхность поликарбоната модифицирована излучением ArF-лазера на длине волны 193 нм с плот-ностями потоков 24—62 мДж/см 2 и числом импульсов 1—100. С помощью сканирующего электронного микроскопа на облученных поверхностях наблюдались заметные изменения в виде микроконусных струк-тур. Показано, что геометрические характеристики (угол при вершине и диаметр основания) микроко-нусов зависят от плотности энергии падающего лазерного излучения. При увеличении плотности энергии излучения угол при вершине микроконусов становится острее, однако диаметры их оснований увеличива-ются. Ключевые слова: микроструктура, лазерно-индуцированный микроконус, облучение поликарбоната, ArF-лазер. Introduction. Laser processing of polymers is an area of active research due mainly to the large number of potential applications in material and biomedical science [1]. Among all these, laser ablation has been extensively used as an effective method for micromachining of polymers because of their unique physical and chemical properties as well as the high quality of resulting patterns. Excimer lasers, as powerful UV sources, have attractive applications in micromachining of polymers [2–4]. In the laser ablation of polymers, which allows the controlled removal of thin surface layers, a variety of surface morphologies evolves that, depending on polymer properties and irradiation conditions, includes periodic and nonperiodic microstructures. Periodic structures have been widely observed in metals, ceramics, polymers, and semiconductors [5]. Among the many aspects of laser abla-tion, we are interested here in conical structures induced by excimer laser radiation on polycarbonate surfaces. Polycarbonate is a thermoplastic polymeric material that plays an important role in tissue engineering. This is due to the surface properties of polycarbonate, such as morphology, hydrophoby, surface energy, surface charge, chemical composition, and so on [6]. To date, much effort has been exerted toward understanding the mechanisms responsible for these laser-induced conical formations on some commercially available polymers. In this paper we report the evolution of 193 nm ArF laser-induced conical structures on polycarbonate as a function of laser flu
Hierarchical Micro-/Nano-Structures on Polycarbonate via UV Pulsed Laser Processing
Nanomaterials
Hierarchical micro/-nanostructures were produced on polycarbonate polymer surfaces by employing a two-step UV-laser processing strategy based on the combination of Direct Laser Interference Patterning (DLIP) of gratings and pillars on the microscale (3 ns, 266 nm, 2 kHz) and subsequently superimposing Laser-induced Periodic Surface Structures (LIPSS; 7–10 ps, 350 nm, 100 kHz) which adds nanoscale surface features. Particular emphasis was laid on the influence of the direction of the laser beam polarization on the morphology of resulting hierarchical surfaces. Scanning electron and atomic force microscopy methods were used for the characterization of the hybrid surface structures. Finite-difference time-domain (FDTD) calculations of the laser intensity distribution on the DLIP structures allowed to address the specific polarization dependence of the LIPSS formation observed in the second processing step. Complementary chemical analyzes by micro-Raman spectroscopy and attenuated total...
Applied Surface Science, 1992
Alomic force microscopy (AFNt) i~ ulilized for the evaluation of change in the surface topography of highly absorbing palm, ethylene terephthalate)(PET)films after UV-laser treatrnenl wilh 248 nm. Three-dimensional data of the surf~,ce micmstructure were taken from ,samples. Particularly low Ilue~ce lreatmem wi~h a few laser pulses was studied. A change in surface topography was ~ound in re,allan to the number of pulses app|ied.
Langmuir, 1999
The morphology of polymer films doped with an infrared dye could be modified significantly with single pulses of a few microseconds from a diode laser with a wavelength of 839 nm. The infrared light was focused into a Gaussian spot having a power density in the center of up to 200 kW/cm 2 . Atomic force microscopy was used to characterize the influence of the infrared-laser power, the pulse width, and the concentration of the embedded infrared dye on the restructuring of the topography of the doped polymer films. Furthermore, the incorporation into the polymer matrix of a thermolabile sulfonium salt combined with acridine as an acid-sensitive fluorescent probe allowed the visualization of the thermally affected area of the irradiated film using laser scanning confocal fluorescence microscopy and scanning near-field optical microscopy. The comparison between irradiated films with poly(methyl methacrylate) and poly(styrene-co-butyl methacrylate) revealed different morphologies in the restructured areas, indicating the important influence of the polymer matrix on the laser action. Experimental evidence was found for the ejection of small droplet like fragments from the irradiated film area. Furthermore, the impact of the infrared irradiation on the film morphology in this study shows close similarities with the restructuring of doped polymer films upon ultraviolet irradiation in earlier reports by Srinivasan, suggesting similar mechanisms for the restructuring at these different irradiation wavelengths.
Oblique argon ion irradiation induced optical and structural modifications of polycarbonate polymer
Oblique ion beam induced modifications in polymeric materials can be treated as an indispensable tool for fabrication of advanced functional materials having wide range of technological applications. In this context, we have examined the influence of 100 keV argon ion irradiation on optical and structural properties of Polycarbonate (PC) polymer at various oblique incidences of 30 0 , 40 0 and 50 0 . UV-visible analysis reveals that optical absorption edge shifted towards the visible region of the spectrum with decrease in angle of incidence which indicate towards the decrease in optical energy gap. A significant increase in Urbach energy (disorder content) from 0.09 eV to 0.795 eV has been observed. Interestingly, with decrease in angle of incidence optical energy gap decreases from 3.06 eV (virgin) to 2.45 eV at lowest angle of 30 0 . Moreover, FTIR transmission spectra shows drastic alterations in transmittance which are associated with structural modifications as a result of oblique ion irradiation. Further, the size of carbon clusters is found to be enhanced with decrease in angle of incidence. The observed optical changes have been further correlated with the structural modifications in the polymeric matrix as a result of oblique ion irradiation.
Influence of CO2 laser radiation on the surface properties of poly(ether ether ketone)
Journal of Applied Polymer Science, 1997
The influence of CO 2 laser radiation on the surface properties of poly(ether ether ketone) (PEEK) is shown. The influence on the surface chemistry is nearly negligible, but the roughness increases and the crystallinity in the surface region decreases with increasing laser intensity. The crystallinity of the surface region was determined by a newly developed procedure using photoacoustic infrared spectroscopy.
Polycarbonate polymer surface modification by extreme ultraviolet (EUV) radiation
Acta Polonica A, 2014
The degree of the biocompatibility of polycarbonate (PC) polymer used as biomaterial can be controlled by surface modication for various biomedical engineering applications. In the past, PC samples were treated by excimer laser for surface reorganization however associated process alteration of bulk properties is reported. Extreme ultraviolet radiation can be employed in order to avoid bulk material alteration due to its limited penetration. In this study, a 10 Hz laser-plasma EUV source based on a double-stream gas-pu target irradiated with a 3 ns and 0.8 J Nd:YAG laser pulse was used to irradiate PC samples. The PC samples were irradiated with dierent number of EUV shots. Pristine and EUV treated samples were investigated by scanning electron microscopy and atomic force microscopy for detailed morphological characterization of micropatterns introduced by the EUV irradiation. Associated chemical modications were investigated by X-ray photoelectron spectroscopy. Pronounced wall-type micro-and nanostructures appeared on the EUV modied surface resulting in a change of surface roughness and wettability.
Surface cross-linking of polycarbonate under irradiation at long wavelengths
Polymer Degradation and Stability, 2004
Depth profiles analyses were performed on a cross section of a photoaged BPAPC substrate by measuring the glass transition temperature and the Young modulus at a microscopic scale. The aim was to define the impact of photochemical modifications induced under UV irradiation upon the physical properties of this polymer. It is well known that ageing of BPAPC begins by a direct phototransformation of the macromolecules according to the photo-Fries rearrangements. These reactions lead to an increase of the free volume and, as a consequence, to a decrease of the temperature associated with the glass transition while in the meantime, the Young modulus of the material is not modified. As ageing proceeds (longer irradiation times), oxidation of the polymer takes place. This oxidative degradation leads to the formation of a cross-linked structure on the exposed surface. This oxidative degradation is associated with an increase of the glass transition temperature and of the Young modulus, whereas in the bulk of the material ageing involves chain scissions characterised by a decreased glass transition temperature.