Simultaneous treatment of polymer surface by EUV radiation and ionized nitrogen

Abstract

In this paper chemical modification of a poly(vinylidene fluoride) surface by extreme ultraviolet (EUV) irradiation in a presence of ionized nitrogen was demonstrated for the first time. Nitrogen gas, injected into an interaction region, was ionized and excited by the EUV radiation from a laser-plasma source. The ionization degree and excited states of nitrogen were investigated using EUV spectrometry and the corresponding spectra are presented. Chemical mod- ification of polymer after combined EUV and ionized nitrogen treatment was investigated using X-ray photoelectron spectroscopy. A significant contribution of nitrogen atoms in near-surface layer of the polymer after the treatment was demonstrated.Polymers are widely used in industry because of good mechanical properties and their resistance to environmental factors. For some applications, however, surface properties of polymers must be modified. The modification may concern hydrophobicity, wettability, adsorption, adhesion, optical or other surface properties and is associated with some changes in physicochemical structure of the near-surface layer. Different methods can be employed for surface structuring, including chemical [1], plasma [2], or radiation treatment. In the last case, ultraviolet (UV) lamps or UV lasers are mainly used [3][4][5]. Photons emitted from these sources can excite electrons from the valence band of polymer materials. Molecular electronic structure of the materials has some resonances, hence, excitation rate depends on energy of the irradiating photons and strongly influences the absorption depth. The excited states can relax through radiative or non-radiative processes. In case of polymers one of the possible radiationless channels corresponds to bond breaking of the polymer chain. This can result in formation of volatile fractions or in changes in chemical structure and composition of the polymer molecules. Some volatile fractions are released from irradiated layer resulting in smooth ablation or modification of the surface morphology due to a preferential dry etching of an amorphous polymer. For some applications incorporation of some functional groups into the polymer molecules is necessary. In such cases irradiation is being performed in a reactive atmosphere [4].

Polycarbonate Polymer Surface Modification by Extreme Ultraviolet (EUV) Radiation

“…An auxiliary gas-pu valve is mounted in the interaction chamber in order to introduce an additional gas (such as helium or nitrogen). Detailed experimental setup and source information can be found in previous publications by our group [13,14]. The PC samples were supplied by Goodfellow Cambridge Ltd. England with 0.06 mm thickness and were irradiated with 100, 200, 300, and 600 EUV shots (as shown in Fig.…”

“…Synthetic and naturally occurring polymers are now becoming an important element in new strategies for producing engineered tissues. Several classes of polymers are now employed in biomedical applications, including situations in which the polymer remains in intimate contact with cells and tissues for prolonged periods [14]. Yet these polymers very often do not possess the surface properties needed for these applications, making it necessary to modify the polymer surface.…”

Modification of Polymer Substrates with Extreme Ultraviolet - Potential Application in Cancer Cell Identification

“…The translationary movements along X and Y planes allow irradiation of 10 by 10 mm area of the polymer samples. The polymer samples were irradiated with 50 or 300 EUV shots at 10 Hz repetition rate in the presence of EUV-ionized nitrogen gas in the interaction region [12]. The detailed arrangement and working of the source on PTFE and other polymers for application in biomedical engineering are documented before [11,13].…”

Laser-plasma extreme ultraviolet and soft X-ray sources based on a double stream gas puff target: interaction of the radiation pulses with matter

“…To attain such effect in case of using UV lasers the surface irradiation is being performed in a reactive atmo− sphere [40]. The author of the paper demonstrated a possi− bility of the EUV treatment in a presence of gases injected into the interaction region synchronously with the radiation pulses [48]. XPS measurements performed for PVDF after irradiation in a presence of the nitrogen gas indicate incor− poration of nitrogen ions into the molecular structure and formation of various functional groups.…”