Poly(tetrafluoroethylene) (PTFE) plates grafted with hydrophilic monomers such as N-isopropylacrylamide (NIP AAm) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) were prepared by the combined use of the plasma treatment and photografting, and their thermo-responsive properties were investigated by ESCA, contact angle measurements and ellipsometry. Since the contact angle values of grafted PTFE decreased with an increase in the grafted amount of PNIP AAm and PDMAEMA, it is considered that the wettabilities of grafted PTFE surfaces come from the hydrophilicity of the grafted polymer chains. At the temperatures above the LCST of PNIP AAm and PDMAEMA aqueous solutions the wettabilities of the grafted PTFE plates were lowered due to the contraction of the grafted polymer chains through hydrophobic interaction. Further, the thickness of the grafted layers of PDMAEMA onto PTFE evaluated by ellipsometry was about 60nm and increased with the grafted amount.

抄録全体を表示

Controlled, plasma-mediated, surface modification of various substrates including inorganic and organic polymers is essential for the creation of miniaturized advanced materials. Many of these approaches have focused on the surface-implantation of specific chemical groups which can be employed for subsequent chemical reactions where molecular recognition plays a significant role (e, g, immobilization of biomolecules; preparation of catalysts, etc.). The deposition of predesigned-structure thin macromolecular layers on various substrate surfaces is another branch of surface modification processes. By creating high specificity surface layers (e. g. chemically inert films, electrically insulating layers, etc.) on commodity materials will open up routes for the development of economical future technologies. In this contribution some of the recent results, generated at the Center for Plasma-Aided Manufacturing, University of Wisconsin-Madison, in the field of RF-plasma-mediated surface deposition and functionalization processes are discussed.

抄録全体を表示

Hexamethyldisilazane (HMDS) was subjected to plasma-assisted chemical vapor deposition (PCVD) for the formation of thin dielectric films on Al substrates for the use as a dielectric electrode in clinical bioelectric measurements. From the measurement of X-ray photoelectron spectroscopy, the PCVD film deposited at higher temperature was found to contain less amount of carbon and tend to approach silicon-nitride-like film. Dielectric loss, tanδ, of the PCVD films deposited on rough Al foil was too large, but it was small enough for the film on a smooth Al plate. The PCVD film deposited at 350°C on Al plate was found to have the greatest dielectric constant, ε_s, as well as the greatest mechanical strength and adhesivity. In the measurement of dielectric properties with a physiological salt solution on the PCVD film as an electrode, the PCVD films showed an excellent barrier property. A possibility for the application to clinical bioelectric measurements was suggested.

抄録全体を表示

Effects of refrigeration of substrates during plasma polymerization were investigated with some fluorocarbons. The refrigeration of a substrate stage which worked also as a lower electrode in a plasma reactor changed the phases, gas-liquid-solid, in the reactor in vacuo the same as under normal atmospheric pressure in the case of hexafluoropropene (HFP). The radiofrequency power which was appropriate for yielding a solid polymer was 20-50W at 230°K in plasma polymerization of HFP, although the RF power was confined to about 10W at 300°K. Deposition rates of these polymers were about 180 Å /min and 225 Å/min, respectively. X-ray photoelectron spectroscopy spectra showed that the reaction proceeded in the presence of a liquid phase HFP. Plasma copolymerization of trifluoromethanesulfonic acid (TFMS), octafluorocyclobutane (OFCB), H₂O and HFP was carried out in the temperature range of 250-270°K. The deposition rate and the electrical conductivity were 220 Å /min and 4.3×10^-7- 3.3×10^-5S/cm, respectively, while the same measurements of the copolymer obtained in the range of 300-310°K were 7 Å/min and 2.4×10^-9-6.1×10^-6S/cm. The former included more F atoms than the latter, and it suggested that the plasma ablation and excessive crosslinking were suppressed. The effects seemed to be derived from differences in the plasma activities between the monomers, and the differences were yielded by their different phase, namely, solids of TFMS and H₂O, a gas of HFP, and an alternation of a liquid and a gas of
OFCB.

抄録全体を表示

Various polymerized organic thin films were deposited on a comb-shaped electrode by using a capacitive-coupled gas flow type plasma polymerization apparatus. The humidity sensing characteristics of these thin films were measured by means of changes in electrostatic capacitance within the frequency and humidity range of 60Hz -100kHz and 20-90%RH, respectively.
The capacitances of these thin film were increased with increasing relative humidity. And the increments of the capacitance grow larger with a lower discharge power and a shorter polymerization time. The linearity and increment of the capacitance change became apparent with the lower frequency of input power to thin films during the capacitance measurements.

抄録全体を表示

Styrene, allylamine and acrylic acid were polymerized by plasma polymerization technique under the ninth polymerization condition from 100W and 50Pa to 200W and 150Pa. We obtained the film-state polymer only under these conditions. The surfaces of plasma-polymerized (pp-) films from styrene, allylamine and acrylic acid were characterized by means of contact angle measurement. The values of contact angle of pp-styrene, pp-allylamine and pp-acrylic acid were widely scattered under the initial stage of nine polymerization conditions. However, these values after 40 days storage under vacuum condition always converged into 87° for pp-styrene, 67° for pp-allylamine and 28° for pp-acrylic acid, respectively. We assumed that this environmental adaptability of contact angle came from the turn over of polar functional groups between polymer surface and bulk.

抄録全体を表示

We have carried out the basic study for controlling the surface condition ( shape ) of the material which has the three-dimensional complex structure, by using the plasma. The plasma surface modification has been used in order to add useful functions to the surfaces of the various materials. However, it is difficult to modify the complex surface structure.
In this study, the simple samples ( models ) which represented the three-dimensional complex structures were developed and modified by O2 plasma. The plasma could reach the material even if it passed through the complex route with twists and turns, and treat the material behind the obstacle. It could change its route of the flow with the obstacle.

抄録全体を表示

The correlation between the light intensity fluctuation and the grain size distribution of excimer laser crystallization (ELC) is investigated using the negative type resist. The sensitivity is dependent on the concentration of the chromophore 3, 3′-diazidodiphenyl sulfone and molecular weight of the resin poly(p-vinylphenol). The γ -characteristics is linear in the fluence region less than 4OmJ/cm2 on 1 shot irradiation. The vertical resolution,
or dynamic range, is 50:1 less than one fourth of CCD camera. The lateral resolution of resist is dependent on the resolution of measurement equipments, and can be guaranteed up to nanometer order by AFM.

抄録全体を表示

A nanofabrication method in which ultrafine and nanometer-sized particles were synthesized in the gas phase and the particles thus obtained were fixed on a substrate was proposed Synthetic method of nanometer-sized aerosol particles from gaseous mixtures of reactive molecules under irradiation with N2 laser light was reported, special attention being paid to the particles involving organosilicon compounds. To improve the efficiency of particle formation in the gas phase, a sensitization method was successfully applied in producing aerosol particles of polyacrolein from acrolein vapor. Advantages of the present method were discussed briefly.

抄録全体を表示

From a gaseous mixture of butyl azide (BAz) and acrolein, sedimentary aerosol particles were produced under irradiation with N₂ laser light, in addition to a film which deposited all over the side wall of the irradiation cell. The yield of the sedimentary aerosol particles, the main chemical component of which was polyacrolein, increased with increasing laser intensity and with increasing the partial pressure of BAz, indicating that BAz increased the efficiency of aerosol particle formation, although its light absorptivity at 337.1nm is very small. To elucidate the nucleation process of the aerosol particles, monitor (He-Ne laser) light intensity scattered by the aerosol particles as formed from the gaseous mixture was measured under
irradiation with N₂ laser light. Characteristic behavior of the scattered light intensity indicated that nucleation proceeded only through the photochemical reaction of BAz at low laser intensity (1.5mJ/pulse), but at higher laser intensity (≥1.9mJ/pulse) nucleation due to photochemical reaction of acrolein followed the nucleation through photochemical reaction of BAz.

抄録全体を表示

Fumarate esters with abstractable hydrogens were found to copolymerize via photoinitiation with a variety of electron donor monomers at a relatively rapid rate under both air and nitrogen. Under air, their copolymerization rates were much faster than monofunctional or difunctional acrylates when a photoinitiator was used to initiate polymerization. Mixtures of dialkylfumarates and N-vinyl formamide (NW) had copolymerization rates faster than dialkylfumarates and N-vinyl pyrrolidone or vinyl ethers. Similar correlations were observed regardless of addition of photoinitiator. From the curing test, difunctional fumarate/NVF system showed faster curing speed than those of multifunctional acrylate with photoinitiator systems.

抄録全体を表示

Photopolymerization of pentaerythritol triacrylate in poly(methylmethacrylate) (PMMA) film using a series of dimethylphenacylsulfonium butyltriphenylborate initiators was investigated. Photopolymerization was studied using real time Fourier transform infrared spectroscopy (RT-FTIR) by irradiating UV light at 365nm. When two aromatic ketones, 2, 4-diethylthioxanthone and 4, 4′-bis(diethylamino)benzophenone, were used as sensitizers, the rate of polymerization (Rp) for the sulfonium borate was higher than for the corresponding sulfonium salt and ammonium borate. The Rp value increased with increasing the reduction potential of the sulfonium cations of the sulfonium borates. The photoreaction between the sulfonium borates and the sensitizers occurred through a photoinduced electron transfer.

抄録全体を表示

Copolymers bearing ß-keto sulfone (ß-KS) groups were prepared, and their photochemical behavior was investigated in films in the presence of amines. The copolymer films turned insoluble on irradiation, and the sensitivity of the insolubilization was enhanced by additive amines. Furthermore, the sensitivity was much raised by the introduction of amino groups in the side-chain of copolymers. The sensitivity was also enhanced by post-exposure bake. Although the sensitivity of the photo-insolubilization of copolymers bearing only ketone groups was enhanced by pendant amino groups, the degree of the enhancement was lower compared to those bearing ß-KS groups. Copolymers bearing only sulfone groups showed enhancement in the sensitivity by the post-exposure bake. Phosphorescence of ß-KS groups was quenched by triethylamine or pendant amino groups. These results suggest that co-existence of ß-KS groups and amino groups not only promotes the generation of radicals in their photo-crosslinking, but also allows the formation of ionic linkages between resulting acid groups and pendant amino groups.

抄録全体を表示

Some photo-macroinitiators were synthesized by reaction of 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, corresponding prepolymers and several isocyanate compounds. These macroinitiators were used for photopolymerization of styrene and methacrylates to produce blockcopolymers. It was confirmed that polyurethane-polystyrene and polyurethane-polyisobutylmethacrylate blockcopolymers were formed by using polyurethane type photo-macroinitiator with high yield. Polyester-polymethylmethacrylate and polydimethylsiloxane -polymethylmethacrylate blockcopolymers were also synthesized with the similar method.

抄録全体を表示

The sulfonium salts which contained naphtyl and α-ester alkyl groups were newly synthesized, for example, 2-naphtylmethyl-1-ethoxycarbonylethyl sulfonium hexafluorophosphate, and their properties as latent catalysts were investigated. The remarkable feature of these sulfonium salts is that they are able to work as the initiators of photo-cationic, photo-radical and thermal cationic polymerization. Because these sulfonium salts could be sensitized by thioxanthone derivatives, it was possible to apply these sulfonium salts to the pigment system, e.g. titanium dioxide contained. And this system showed the same photoactivities as the usual photo-radical initiators, and efficiently polymerized radical monomers. In the hybrid system, the reactivities of these sulfonium salts in the presence of photosensitizer were superior to those of triarylsulfonium salt (UVI-6990) and 2, 2-dimethoxy-1, 2-diphenylethane-1-one (IC-651). Further, these sulfonium salts were able to polymerize cycloaliphatic epoxides (UVR-6110) at 130°C, therefore the application of sulfonium salts to the thermal curing system was also expected in the field which required after-cure followed photopolymerization.

抄録全体を表示

The photopolymerization of cyclohexene oxide (CHO) was carried out in the presence of fluorenyltriphenylphosphonium hexafluoroantimonate (1_SbF6) (0.5mol %) in dichloromethane at 30°C under irradiation with a 400W high-pressure mercury lamp to find that the polymerization of CHO took place as soon as the irradiation started, although it did not proceed in the dark. The fluorenyltriphenylphosphonium salt 1_SbF6 showed dramatically higher activity than the corresponding benzyltriphenylphosphonium salt.

抄録全体を表示

Radiation curable polyurethane-based microspheres were prepared. Vinyl groups were introduced to the side chains and the ends of the polyurethane main chains. Photoinitiators and multifunctional acrylates oligomers were incorporated in each microsphere. The curing behavior of the films cast from the microspheres under UV irradiation were studied. The effect of the incorporation of multifunctional acrylates oligomers on MEK resistance of UV cured films was observed. The curing behavior of the films was followed by real time FT-IR spectroscopy. The accelerating effect of the incorporation of multifunctional acrylates became striking particularly at the early stage of curing process. Multifunctional acrylates were found to be effective to raise the extent of the conversion of the double bonds. The curing behavior under UV irradiation was compared with that under EB irradiation.

抄録全体を表示