- Email: [email protected]
RF-plasma deposited polymerlike thin films: preparation, properties and applications
Abstracts
are important in many biomedical applications. Moreover, patient discomfort due to poor lubricating action between tissue and various medical devices, especially contact lenses, is a serious medical problem. An effective polymer for protein-resistant surfaces and super lubrication properties appears to be polyethylene oxide (PEO) 2'3. Here we report a study of PEO films on low temperature isotropic (LTI) carbon surfaces, including preparation using a photochemical reaction, characterization of the thickness of the PEO layer by ellipsometry and measurement of the coefficient of friction with a custom built tribometer. The uv-induced reaction of PEO onto carbon surfaces has been studied. The LTI carbon surfaces examined under optical microscopy are smooth. The cleaned sample is submerged in methanol before treatment in a PEO/H20 solution [BBEPEG(3350)-OH in H20, 5 mg m l - 1] for 10 min 4. The sample is rinsed using deionized (DI) water and is dried in air. The sample surface is exposed to uv light of 4.7 mW cm 2 for 5 min and then stored in DI water. The samples are air dried, and then ellipsometry measurements (RUDOLPH RESEARCH RR2000 Automatic Ellipsometer) made to determine the optical parameters of PEO layer. A series of experiments has been done to analyze the film thickness. The results of ellipsometric measurements suggest that the uvinduced reaction PEO on the LTI carbon surface is of about 25/~ thick, and is very difficult to remove. These suggest that a photochemical reaction resulted in the covalent binding of the PEO molecules to the carbon surface. Friction and lubrication phenomena on the PEO film have also been investigated. Friction forces were measured in air for both the LTI carbon surface and the LTI carbon surface coated with a PEO layer using the same process. The coefficient of friction of the LTI surface with a PEO layer, about 0.17, is less than that of the LTI surface alone, about 0.35. This suggests that an added PEO layer is helpful in improving lubrication. Photoactive PEO has been used for glass eyes 5. Patients feel more comfortable wearing artificial eyes coated with a layer of PEO due to better lubrication of the eyes. PEO will be a very useful coating for contact lens and other various medical devices in the future because of better lubrication properties and biocompatibility.
ous dispersion. Being mixed with MXS agent, the aqueous dispersion was to be done as a milky white liquid consisting of very small particles (diameter distribution 0.44).6 pm) suspended in water. After coating drying sintering, the film was formed. Microcellular fluorocarbon foams have been discerned with the blowing puffy method, scanning electron microscope and X-ray diffractometer; their results are low-density 0.3842, thickness 150 #m, rate of air flow 2 I cm- 2 atom min, average porous size 0.1~).2 pm and amorphous structure 70%. Its characteristic shows a good property as air filter membrane for excluding the bacterium in fermentation and medicinal applications.
Second order nonlinear optical properties of 4-(N-methyl, N-hexadecylamino)-4'-dicyanovinyl-azobenzene (MHDCAB) Shen Yuquan, Shen Jifeng, Fu Xingfa and Yu Qun, Institute of Photographic Chemistry, Academia Sinica, Beijing 100101, China ; Xu Yu, Liu Yunqi, Yang Chun and Zhu Daoben, Institute of Chemistry, Academia Sinica, Beijing 100080, China; and Wang Wencheng and Liu Liying, Department of Physics, Fudan University, Shanghai 200433, China MHDCAB was synthesized and designed to have a large molecular second order susceptibility ft. It has been assembled in LB film in noncentrosymmetric manner, as it is shown in SHG measurement. The fl was measured in transmission geometry using 1.06 #m output from a N d : Y A G mode-locked laser. A 2/4 plate and a Glan polarizer were used to vary the polarization direction of the laser beam. The ratio of I57p vs IS2wp is large, a factor of 9.9, indicating that the dipole of the molecules is nearly perpendicular to the film. The fl was measured to be 5.23 x 10-28 esu. The SHG was measured 10 days after deposition of the LB film. The film was kept at ambient temperature around 30°C. The randomization of the dipole orientation seems not serious. Part of the large nonlinearity observed probably is contributed by J-aggregate. MHDCAB is transparent in near ir and photochemically it is reasonably stable.
References i j D Andrade and V Hlady, Adv Polymer Sci, 79, 1 (1986). 2 j H Lee, J Kopecek and J D Andrade, J Biomed Mater Res, 23, 355 (1989). 3 p M McGuigga, J N Israelachvili, M L Gee and A M Homola, Mater Res Sod Syrup Proc, 140, 79 (1989). 4S C Dunkirk and P E Guire, Surface-Modification of Polymers for Increased Wettability, The 15th Annual Meeting of the Society for Biomaterials, 28 April-2 May 1989, Lake Buena Vista, Florida, USA. 5BioCoat Ocular Prosthesis Treatment, Literature from Bio-Metric Systems, Inc, 9924 W 74th Street, Eden Prairie, MN 55344, USA.
Amorphous microceHular polytetrafluoroethylene (PTFE) foam film Tang Chongzheng and Kong Yikching, Materials Science Research Institute, South China University of Technology, Guangzhou 510641, China Polytetrafluoroethylene (PTFE) foam film was made by aque1066
RF-plasma deposited polymerlike thin films: preparation, properties and applications Wang Jue and Hua Yinzeng, Physics Department, Tongji University, Shanghai 200092, China; and Ji Huamei, Shanghai Institute of Technical Physics, Academia Sinica, Shanghai 200083, China The deposition of polymerlike thin films from benzene vapor diluted with Ar gas at relatively low temperature and low pressure in a rf plasma is described. The typical deposition parameters were determined. The polymerlike films are slightly colored and show no reaction to many kinds of solutions (ethylether, ethyl alcohol, acetone, benzene, carbon disulfide, chloroform and so on). The electron transmission micrograph of the film indicates that it has cross-linked structure. The infrared absorption spectra of both the deposited films and the benzene monomer were measured. The structure of the deposited film was verified by infrared absorption analysis. It implies that the deposited film is
Abstracts
highly polymerized and has a dense structure of regular crosslinked network with only a few radicals. It is also found that the film is stable. There are no obvious free radicals in the films. Besides, the infrared absorptions caused by the oscillations of O - - H and C = O structures were observed. It is demonstrated that the presence of residual water vapor and oxygen in the discharge tube results in the formation of the observed O - - H and C------Ogroups. Since low-Z, oxygen-free thin films with structure integrity are desirable materials for the X-ray laser program, one of the objectives of this work was the application of the polymerlike films as substrates of X-ray laser targets. Owing to their insolubility and relatively high softening temperature, the polymerlike films have been used as substrates to produce thin sulfur targets in CS2 solution and thin germanium targets by electron beam evaporation.
target show different properties. The effect of excess PbO and dopants in PZT target on the rate of sputtering and film structure is discussed. The effect of gas ambient (argon and a r g o n + + oxygen) on the structure of the films is demonstrated for ZnO. The dielectric anomaly may be completely masked in ferroelectric films due to series resistance of electrodes and the interface barrier, even for those films which have the desired composition and structure. The influence of sputtering parameters on the interface states and fiat band shift in metal-oxidesilicon structure and their implications in device application has also been discussed for ZnO and PZT films.
Optical properties of oxide coatings deposited by dual-ion-beam sputter Charge build-up in polypropylene thin films Ding Hai, Pohl Institute, Tongji University, Siping Road 1239, Shanghai 200092, China Irradiation of insulating polymer films with nonpenetrating electron beams results in long-lasting space charge. The charge storage properties of polymer electrets are most important for their application. The location of the charge and the radiation-induced conductivity are interesting both for production of foil electrets and for the investigation of charge phenomena in such materials. In this paper, charge build-up in 30 #m thick films of polypropylene irradiated with monoenergetic electron beams of 1054 keV energy is investigated. Using the split-Faraday cap, the mean charge depth at the beginning of electron injection, at the termination of injection, and 10 min after injection are measured. It is found that the depth increases with time during charging, but decreases a little after injection of electron beams. The charge depth increases also with the amount of injected charge. From the dynamics of charge motion during irradiation, the radiationinduced conductivity is determined as a function of dose rate. It amounts to approximately 10-14 cm 1 at 10 4 rad s - J.
Invited paper
Tang Xuefei, Fan Zhengxiu and Wang Zhijiang, Shanghai Institute of Optics and Fine Mechanics, Academia Sinica, PO Box 800211, Shanghai 201800, China The optical properties of single-layer TiO2, ZrO2 and SiO2 films deposited by dual-ion-beam sputter (DIBS) have been investigated and compared with films of the same materials deposited by thermal evaporation and ion assisted deposition (IAD). F o r DIBS deposition, the following deposition parameters were varied : composition of the sputter deposition gas mixture, composition of the ion assist gas mixture, temperature of substrates, and ion energy and ion current density for the ion assist beam. The influences of deposition parameters on optical properties of films deposited by DIBS are discussed. For DIBS films, the index of refraction approaches the bulk material values, the optical absorptions are much lower than those of films deposited by thermal evaporation and IAD, and the laser-induced damage thresholds (LIDT) are higher. High reflector coatings and antireflective coatings were deposited utilizing the optimum deposition parameters obtained from the single-layer studies. The reflections, optical absorptions and LIDT measurements of these films are reported. Electron micrographs of the surface and fractured cross-section of single-layer and multi-layer films deposited by DIBS are given and compared with films deposited by thermal evaporation and IAD.
Fabrication and characterization of rf sputtered oxide films Abhai Mansingh, Department of Physics and Astrophysics, University of Delhi, Delhi 110 007, India The effect of sputtering parameters on the growth and properties of transparent conducting (tin dipped indium oxide, ITO) piezoelectric (zinc oxide, ZnO) and ferroelectric (lead zirconate titanate, PZT) films is discussed. The effect of target substrate distance (in the range 2-7 cm) has been investigated in detail. In ITO the formation of the virtual source (thermalisation distance) has been established for oxide target sputtered in argon ambient, and it shifts towards the target when a small amount of oxygen is introduced. The properties of films depend on whether the substrate is above or below the virtual source. In PZT the formation of the virtual source is not clearly established but the films deposited at T-S distance above and below 4 cm from the
Sputtering of silicate glasses Shinya Miyazaki, Teruhiko Kai, Hiromichi Takebe and Kenji Morinaga, Department of Materials Science and Technology, Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakouen, Kasuga-shi, Fukuoka 816, Japan Silicon dioxide and silicate glass films were prepared by rfsputtering. Changes in thickness, composition, and structure of the films with sputtering time were investigated. High resolution X-ray fluorescence spectrometry and infrared spectroscopy were used to characterize the state of silicate anion in the films. We propose the sputtering mechanism of the silicate glasses. 1067
are important in many biomedical applications. Moreover, patient discomfort due to poor lubricating action between tissue and various medical devices, especially contact lenses, is a serious medical problem. An effective polymer for protein-resistant surfaces and super lubrication properties appears to be polyethylene oxide (PEO) 2'3. Here we report a study of PEO films on low temperature isotropic (LTI) carbon surfaces, including preparation using a photochemical reaction, characterization of the thickness of the PEO layer by ellipsometry and measurement of the coefficient of friction with a custom built tribometer. The uv-induced reaction of PEO onto carbon surfaces has been studied. The LTI carbon surfaces examined under optical microscopy are smooth. The cleaned sample is submerged in methanol before treatment in a PEO/H20 solution [BBEPEG(3350)-OH in H20, 5 mg m l - 1] for 10 min 4. The sample is rinsed using deionized (DI) water and is dried in air. The sample surface is exposed to uv light of 4.7 mW cm 2 for 5 min and then stored in DI water. The samples are air dried, and then ellipsometry measurements (RUDOLPH RESEARCH RR2000 Automatic Ellipsometer) made to determine the optical parameters of PEO layer. A series of experiments has been done to analyze the film thickness. The results of ellipsometric measurements suggest that the uvinduced reaction PEO on the LTI carbon surface is of about 25/~ thick, and is very difficult to remove. These suggest that a photochemical reaction resulted in the covalent binding of the PEO molecules to the carbon surface. Friction and lubrication phenomena on the PEO film have also been investigated. Friction forces were measured in air for both the LTI carbon surface and the LTI carbon surface coated with a PEO layer using the same process. The coefficient of friction of the LTI surface with a PEO layer, about 0.17, is less than that of the LTI surface alone, about 0.35. This suggests that an added PEO layer is helpful in improving lubrication. Photoactive PEO has been used for glass eyes 5. Patients feel more comfortable wearing artificial eyes coated with a layer of PEO due to better lubrication of the eyes. PEO will be a very useful coating for contact lens and other various medical devices in the future because of better lubrication properties and biocompatibility.
ous dispersion. Being mixed with MXS agent, the aqueous dispersion was to be done as a milky white liquid consisting of very small particles (diameter distribution 0.44).6 pm) suspended in water. After coating drying sintering, the film was formed. Microcellular fluorocarbon foams have been discerned with the blowing puffy method, scanning electron microscope and X-ray diffractometer; their results are low-density 0.3842, thickness 150 #m, rate of air flow 2 I cm- 2 atom min, average porous size 0.1~).2 pm and amorphous structure 70%. Its characteristic shows a good property as air filter membrane for excluding the bacterium in fermentation and medicinal applications.
Second order nonlinear optical properties of 4-(N-methyl, N-hexadecylamino)-4'-dicyanovinyl-azobenzene (MHDCAB) Shen Yuquan, Shen Jifeng, Fu Xingfa and Yu Qun, Institute of Photographic Chemistry, Academia Sinica, Beijing 100101, China ; Xu Yu, Liu Yunqi, Yang Chun and Zhu Daoben, Institute of Chemistry, Academia Sinica, Beijing 100080, China; and Wang Wencheng and Liu Liying, Department of Physics, Fudan University, Shanghai 200433, China MHDCAB was synthesized and designed to have a large molecular second order susceptibility ft. It has been assembled in LB film in noncentrosymmetric manner, as it is shown in SHG measurement. The fl was measured in transmission geometry using 1.06 #m output from a N d : Y A G mode-locked laser. A 2/4 plate and a Glan polarizer were used to vary the polarization direction of the laser beam. The ratio of I57p vs IS2wp is large, a factor of 9.9, indicating that the dipole of the molecules is nearly perpendicular to the film. The fl was measured to be 5.23 x 10-28 esu. The SHG was measured 10 days after deposition of the LB film. The film was kept at ambient temperature around 30°C. The randomization of the dipole orientation seems not serious. Part of the large nonlinearity observed probably is contributed by J-aggregate. MHDCAB is transparent in near ir and photochemically it is reasonably stable.
References i j D Andrade and V Hlady, Adv Polymer Sci, 79, 1 (1986). 2 j H Lee, J Kopecek and J D Andrade, J Biomed Mater Res, 23, 355 (1989). 3 p M McGuigga, J N Israelachvili, M L Gee and A M Homola, Mater Res Sod Syrup Proc, 140, 79 (1989). 4S C Dunkirk and P E Guire, Surface-Modification of Polymers for Increased Wettability, The 15th Annual Meeting of the Society for Biomaterials, 28 April-2 May 1989, Lake Buena Vista, Florida, USA. 5BioCoat Ocular Prosthesis Treatment, Literature from Bio-Metric Systems, Inc, 9924 W 74th Street, Eden Prairie, MN 55344, USA.
Amorphous microceHular polytetrafluoroethylene (PTFE) foam film Tang Chongzheng and Kong Yikching, Materials Science Research Institute, South China University of Technology, Guangzhou 510641, China Polytetrafluoroethylene (PTFE) foam film was made by aque1066
RF-plasma deposited polymerlike thin films: preparation, properties and applications Wang Jue and Hua Yinzeng, Physics Department, Tongji University, Shanghai 200092, China; and Ji Huamei, Shanghai Institute of Technical Physics, Academia Sinica, Shanghai 200083, China The deposition of polymerlike thin films from benzene vapor diluted with Ar gas at relatively low temperature and low pressure in a rf plasma is described. The typical deposition parameters were determined. The polymerlike films are slightly colored and show no reaction to many kinds of solutions (ethylether, ethyl alcohol, acetone, benzene, carbon disulfide, chloroform and so on). The electron transmission micrograph of the film indicates that it has cross-linked structure. The infrared absorption spectra of both the deposited films and the benzene monomer were measured. The structure of the deposited film was verified by infrared absorption analysis. It implies that the deposited film is
Abstracts
highly polymerized and has a dense structure of regular crosslinked network with only a few radicals. It is also found that the film is stable. There are no obvious free radicals in the films. Besides, the infrared absorptions caused by the oscillations of O - - H and C = O structures were observed. It is demonstrated that the presence of residual water vapor and oxygen in the discharge tube results in the formation of the observed O - - H and C------Ogroups. Since low-Z, oxygen-free thin films with structure integrity are desirable materials for the X-ray laser program, one of the objectives of this work was the application of the polymerlike films as substrates of X-ray laser targets. Owing to their insolubility and relatively high softening temperature, the polymerlike films have been used as substrates to produce thin sulfur targets in CS2 solution and thin germanium targets by electron beam evaporation.
target show different properties. The effect of excess PbO and dopants in PZT target on the rate of sputtering and film structure is discussed. The effect of gas ambient (argon and a r g o n + + oxygen) on the structure of the films is demonstrated for ZnO. The dielectric anomaly may be completely masked in ferroelectric films due to series resistance of electrodes and the interface barrier, even for those films which have the desired composition and structure. The influence of sputtering parameters on the interface states and fiat band shift in metal-oxidesilicon structure and their implications in device application has also been discussed for ZnO and PZT films.
Optical properties of oxide coatings deposited by dual-ion-beam sputter Charge build-up in polypropylene thin films Ding Hai, Pohl Institute, Tongji University, Siping Road 1239, Shanghai 200092, China Irradiation of insulating polymer films with nonpenetrating electron beams results in long-lasting space charge. The charge storage properties of polymer electrets are most important for their application. The location of the charge and the radiation-induced conductivity are interesting both for production of foil electrets and for the investigation of charge phenomena in such materials. In this paper, charge build-up in 30 #m thick films of polypropylene irradiated with monoenergetic electron beams of 1054 keV energy is investigated. Using the split-Faraday cap, the mean charge depth at the beginning of electron injection, at the termination of injection, and 10 min after injection are measured. It is found that the depth increases with time during charging, but decreases a little after injection of electron beams. The charge depth increases also with the amount of injected charge. From the dynamics of charge motion during irradiation, the radiationinduced conductivity is determined as a function of dose rate. It amounts to approximately 10-14 cm 1 at 10 4 rad s - J.
Invited paper
Tang Xuefei, Fan Zhengxiu and Wang Zhijiang, Shanghai Institute of Optics and Fine Mechanics, Academia Sinica, PO Box 800211, Shanghai 201800, China The optical properties of single-layer TiO2, ZrO2 and SiO2 films deposited by dual-ion-beam sputter (DIBS) have been investigated and compared with films of the same materials deposited by thermal evaporation and ion assisted deposition (IAD). F o r DIBS deposition, the following deposition parameters were varied : composition of the sputter deposition gas mixture, composition of the ion assist gas mixture, temperature of substrates, and ion energy and ion current density for the ion assist beam. The influences of deposition parameters on optical properties of films deposited by DIBS are discussed. For DIBS films, the index of refraction approaches the bulk material values, the optical absorptions are much lower than those of films deposited by thermal evaporation and IAD, and the laser-induced damage thresholds (LIDT) are higher. High reflector coatings and antireflective coatings were deposited utilizing the optimum deposition parameters obtained from the single-layer studies. The reflections, optical absorptions and LIDT measurements of these films are reported. Electron micrographs of the surface and fractured cross-section of single-layer and multi-layer films deposited by DIBS are given and compared with films deposited by thermal evaporation and IAD.
Fabrication and characterization of rf sputtered oxide films Abhai Mansingh, Department of Physics and Astrophysics, University of Delhi, Delhi 110 007, India The effect of sputtering parameters on the growth and properties of transparent conducting (tin dipped indium oxide, ITO) piezoelectric (zinc oxide, ZnO) and ferroelectric (lead zirconate titanate, PZT) films is discussed. The effect of target substrate distance (in the range 2-7 cm) has been investigated in detail. In ITO the formation of the virtual source (thermalisation distance) has been established for oxide target sputtered in argon ambient, and it shifts towards the target when a small amount of oxygen is introduced. The properties of films depend on whether the substrate is above or below the virtual source. In PZT the formation of the virtual source is not clearly established but the films deposited at T-S distance above and below 4 cm from the
Sputtering of silicate glasses Shinya Miyazaki, Teruhiko Kai, Hiromichi Takebe and Kenji Morinaga, Department of Materials Science and Technology, Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakouen, Kasuga-shi, Fukuoka 816, Japan Silicon dioxide and silicate glass films were prepared by rfsputtering. Changes in thickness, composition, and structure of the films with sputtering time were investigated. High resolution X-ray fluorescence spectrometry and infrared spectroscopy were used to characterize the state of silicate anion in the films. We propose the sputtering mechanism of the silicate glasses. 1067