UV Irradiation Of Films Research Articles

Microwave photocatalysis of mono-chloroacetic acid over nanoporous titanium(IV) oxide thin films using mercury electrodeless discharge lamps

The degradation of mono-chloroacetic acid (MCAA) by microwave-assisted photocatalysis has been examined by a new method. A novel electrodeless discharge lamp (EDL) was employed as UV light source generated by microwave irradiation. Titanium(IV) oxide film was used as the photocatalyst due to its superior characteristics. Several factors influencing the degradation of MCAA, such as number of coating cycles, light intensity, initial pH value, gas bubbling, and H 2O 2 dosage have been studied in detail. Mono-chloroacetic acid was efficiently decomposed to HCl, CO 2, and H 2O by the UV irradiated titanium dioxide thin film in a microwave field. The decomposition was enhanced in an alkaline solution and in the presence of H 2O 2, and significantly enhanced by increasing the intensity of UV light.

Fabrication and Characterization of Direct-patternable PZT Film Prepared by Photochemical Metal-organic Deposition

The ferroelectric properties of UV irradiated and non-irradiated PZT films prepared via photochemical metal-organic deposition using photosensitive precursors were characterized. Fourier transform infrared spectroscopy showed that complete removal of organic groups was possible through UV exposure of the spin-coated PZT precursor films at room temperature. The measured remnant polarization values of UV- irradiated and non-irradiated PZT films after annealing at 650 C were 29 and 23 µC/cm , respectively. The UV irradiation was found to be effective for the enhancement of the growth orientation and ferroelectric property of PZT film and in the direct patterning in the fabrication of micro-patterned systems without dry etching.

Study on the Electrical Properties of Direct-Patternable SBT Films Formed by Photochemical Metal-Organic Deposition

The ferroelectric properties of UV irradiated and non-irradiated SBT thin films using photosensitive starting precursors were investigated. The observation of surface microstructure showed that UV irradiation and increase in anneal temperature induced the grain growth of SBT. The measured remnant polarization values of UV irradiated and non-irradiated SBT films after anneal at 700oC were 5.8 and 4.7 )C/cm2 and after anneal at 750oC, the values were 10.8 and 9.3 )C/cm2, respectively.

X-ray Photoelectron and C K-Edge X-ray Absorption Spectroscopic Analysis of an UV Irradiated Polyimide Film

X-ray Photoelectron and C K-Edge X-ray Absorption Spectroscopic Analysis of an UV Irradiated Polyimide Film

Effect of UV irradiation on cellulase degradation of cellulose acetate containing TiO2

Cellulose acetate (CA) films containing anatase type titanium dioxide (TiO2) nanoparticles were prepared by solution casting. The film surface was modified by UV irradiation using a grid type UV irradiator. The UV irradiation caused slight increase in photodegradation of the CA films with TiO2 compared to the CA film alone. However, CA films irrespective of TiO2 content did not show a significant enzymatic degradation by a cellulase fromAspergillus niger without UV irradiation. Upon UV irradiation, the biodegradability remarkably improved even in the CA film without TiO2. The irradiation of CA films decreased both the water contact angle and the degree of substitution (DS) implying the decrease in acetyl groups of the CA film surface due to the photo-scission of the acetyl group and photooxidation, resulting in more facile biodegradation of the surface film layer. The substantial enhancement in biodegradation of the UV irradiated CA film containing TiO2 was attributed to the increased hydrophilicity, lowered DS and zeta potential due to the photoscission and the photooxidation effect of UV light. Also the increased surface area of the CA film due to the photocatalysis of TiO2 particles may encourage the facile biodegradation.

Unusual photo-induced behaviour in a side chain liquid crystalline azo-polyester

An unusual behaviour has been observed in the photo-induced response of an azobenzene side chain liquid crystalline polyester (P6d4). Room temperature irradiation with linearly polarised 488 nm light does not induce any birefringence (Δ n) in films of this polymer that have been quenched from the isotropic state. However, using the same irradiation conditions Δ n is induced in quenched films that have been kept in darkness for a few minutes. Besides, no photo-induced Δ n is observed in films irradiated with 488 nm light that have been previously irradiated with UV light. In this case, Δ n can be recorded if the UV irradiated films have been kept in darkness for several hours. In another set of experiments performed with the P6d4 polymer, irradiation with high intensity linearly polarised 488 nm light induces an initial increase of Δ n and then it goes back to zero. Subsequent irradiation with linearly polarised 633 nm light induces an orientation of the azobenzene chromophores perpendicular to the polarisation of the 488 nm light and independent of the 633 nm light polarisation direction. These results are very different from those obtained in other side chain polyesters which only differ from P6d4 in the end substituent. The anomalous behaviour of P6d4 is discussed in terms of a supercooling effect of the isotropic phase, the trans to cis back isomerization, the trans aggregation kinetics and a memory effect associated with the main chain orientation.

Photosensitive PVA Polarizing Film

In order to analyze the polarization of Poly(vinyl alcohol) (PVA) film, both the polarizing film and polarizing film exposed to UV light were prepared and investigated by X-ray diffractometer (XRD) and polarized UV-Visible Spectrometer. Through a series of experiments, it was found that the crystallization degree of the unirradiated PVA film was higher than that of the UV-irradiated PVA film. Furthermore, the transmittance of both unirradiated PVA film and UV-irradiated PVA film was selective, different wavelength and different polarizing angles parallelism different light transmittance.

Deposition of graded TiO 2 films featured both hydrophobic and photo-induced hydrophilic properties

Graded TiO 2 films were deposited on unheated glass substrates by using a twin dc magnetron sputtering system. The graded TiO 2 films showed a highly polycrystalline structure of anatase with a little rutile phases revealed by X-ray diffraction spectra. The surface energy of the fresh and UV irradiated films were evaluated by water contact angle measurement. The results indicated that the water contact angle of the fresh graded TiO 2 films was found within 100–112°. The films then became a highly hydrophilic surface with the water contact angle of almost zero under 60 min UV irradiation. The XPS spectrum of Ti 2p revealed that the graded TiO 2 films became a stoichiometric titanium oxide layer near the surface, proving that titanium was fully oxidized. It was found that the surface OH group density depended on the substrates employed for given sputtering conditions. In addition, AFM images revealed a considerably rough surface of the graded films with RMS roughness of 12.6–14.5 nm. One can conclude that the unique properties of highly hydrophobicity and photo-induced hydrophilicity can be attributed to fully oxidized chemical composition and higher roughness on the film surface.

Modulation of refractive index and thickness of poly(methyl methacrylate) thin films with UV irradiation and heat treatment

This paper reports changes in refractive index and thickness of spin-coated poly(methyl methacrylate) (PMMA) thin films upon irradiation by a conventional high-pressure mercury UV lamp. Significant increase in refractive index and reduction in thickness are detected. Index modulations of greater than 0.01 are achieved in the thin films after 4 min of irradiation. The thickness reduction of an irradiated PMMA film is consistent with its weight loss. This is caused by the escape of the volatile molecules generated during the irradiation process. A slight increase in the refractive index is also found in the film, heat-treated above its glass transition temperature (Tg). This thermal effect is detected in the UV irradiation process. We propose three possible aliphatic structures that are formed during the photochemical reaction and may exist in the main chain of irradiated PMMA after the irradiation. Their refractive indices in aggregate state are greater than that of PMMA based on an evaluation using the Lorentz–Lorenz equation. This is suggested to be an important reason for the refractive index increase in the UV-irradiated PMMA films. A UV-irradiated film, heat-treated above its Tg, has a rough surface with many tiny holes as illustrated by atomic force microscopy. These holes are attributed to the evaporation of the small molecules generated during the irradiation process.

UV 노광과 RTA 공정의 도입이 Sol-Gel 법으로 제조한 강유전성 Sr0.9Bi2.1Ta1.8Nb0.2O9박막의 결정성 및 유전/전기적 특성에 미치는 영향

The ferroelectric SBT thin films as a material of capacitors for non-volatile FRAMs have some problems that its remanent polarization value is relatively low and the crystallization temperature is quite high abovc 80<TEX>$0^{\circ}C$</TEX>. Therefore, in this paper, SBTN solution with S <TEX>$r_{0.9}$</TEX>B <TEX>$i_{2.1}$</TEX>T <TEX>$a_{1.8}$</TEX>N <TEX>$b_{0.2}$</TEX><TEX>$O_{9}$</TEX> composition was synthesized by sol-gel method. Sr(O <TEX>$C_2$</TEX> <TEX>$H_{5}$</TEX>)<TEX>$_2$</TEX>, Bi(TMHD)<TEX>$_3$</TEX>, Ta(O <TEX>$C_2$</TEX> <TEX>$H_{5}$</TEX>)<TEX>$_{5}$</TEX>and Nb(O <TEX>$C_2$</TEX> <TEX>$H_{5}$</TEX>)<TEX>$_{5}$</TEX> were used as precursors, which were dissolved in 2-methoxyethanol. SBTN thin films with 200 nm thickness were deposited on Pt/Ti <TEX>$O_2$</TEX>/ <TEX>$SiO_2$</TEX>/Si substrates by spin-coating. UV-irradiation in a power of 200 W for 10 min and rapid thermal annealing in a 5-Torr-oxygen ambient at 76<TEX>$0^{\circ}C$</TEX> for 60 sec were used to promote crystallization. The films were well crystallized and fine-grained after annealing at <TEX>$650^{\circ}C$</TEX> in oxygen ambient. The electrical characteristics of 2Pr=11.94 <TEX>$\mu$</TEX>C/<TEX>$\textrm{cm}^2$</TEX>, Ps＋/Pr＋=0.54 at the applied voltage of 5 V were obtained for a 200-nm-thick SBTN films. This results show that 2Pr values of the UV irradiated and rapid thermal annealed SBTN thin films at the applied voltage of 5 V were about 57% higher than those of no additional processed SBTN thin films. thin films.lms.s.s.

Anisotropic Molecular Orientation of Liquid Crystal Monolayer in Contact with UV-irradiated Polyimide Film

By polarized infrared (IR) absorption spectroscopy we have determined the in-plane anisotropy in the molecular orientation of a liquid crystal (LC) monolayer in contact with a polyimide film exposed to linearly polarized ultraviolet light (LPUVL). The in-plane anisotropy of the underlying polyimide film surface was also determined. The average orientational directions of the LC molecules and the polyimide molecules were the same, both being perpendicular to the polarization direction of LPUVL. The in-plane molecular order of the LC molecules was smaller than that of the polyimide molecules. This result indicates that the anisotropic orientational distribution of the LC molecules in contact with the LPUVL-exposed polyimide film is induced through a short-range interaction between the LC molecules and the polyimide molecules.

UV-irradiated biodegradability of ethylene--propylene copolymers, LDPE, and I-PP in composting and culture environments.

The biodegradability of UV-irradiated films of ethylene--propylene copolymers (E--P copolymer), isotactic polypropylene (i-PP), and low-density polyethylene (LDPE), was measured in composting and culture environments by monitoring the variations in intrinsic viscosity [eta], weight loss per surface area, surface changes by SEM, colonization of fungus, chain scission, and evolution of hydroxyl and carbonyl groups by FT-IR spectroscopy. Photooxidation was used as a pretreatment for biodegradation of polymers. A systematic decrease in intrinsic viscosity [eta] and increase in carbonyl/hydroxyl regions in FT-IR spectra was found from 0 to 100-h irradiated samples. The degradation rate was strongly dependent on the composition of copolymers and markedly increased with decrease in ethylene content. Important surface erosion was detected after composting by SEM for longer UV-irradiated samples. It was estimated that chain-scission was directly related to photoirradiation.

Photoactive Cholesteric Polymeric Material With Dual Photochromism

ABSTRACTNew cholesteric polymeric material containing a liquid crystalline (LC) copolymer with side phenylbenzoate nematogenic and photochromic spiropyran groups and 5 mol % chiral photochromic dopant based on cinnamic acid and isosorbide was prepared. It was shown that UV irradiation and subsequent annealing of planarly-oriented mixture films lead to untwisting of the cholesteric helix and cause an irreversible shift of selective light reflection to the long-wavelength region. This process is explained by the E-Z isomerization of chiral photochromic groups of the dopant relative to a C=C bond accompanied by a decrease in their twisting ability. Upon UV irradiation of films at room temperature, a thermally reversible transformation of spiropyran groups into a merocyanine form takes place, which is followed by the appearance of an intense absorption maximum in the visible spectral region. It was shown, that the use of the material prepared in this work provides an opportunity to record two images at a time: one image is due to a change in the helical pitch and another image (above) is due to the photochromism of spiropyran groups. It is pertinent to note that using the approach developed in this work allows one to widely vary the range of materials exhibiting dual photochromism. It was demonstrated that the mixture under examination shows promise as new photosensitive material for optics, optoelectronics, and data recording.

Preparation of insolubilized-DNA film with three-dimensional network and removal of endocrine disruptors.

A water-insolubilized film was prepared by UV irradiation on a dried DNA film. When a UV-irradiated DNA was examined using a circular dichroism spectroscopy, a double stranded structure was observed as well as that of native DNA. The UV irradiated DNA film was also accumulated intercalating reagents. These results suggested that the double stranded structure was involved in the UV irradiated DNA film with a three-dimensional network. The thymine-thymine dimer formation was suggested to be involved in the cross-linking reactions by the polymerization analysis using poly(dA)-poly(dT) and poly(dG)-poly(dC). We also demonstrate the utilization of the UV-irradiated DNA film as a functional material for the accumulation of harmful DNA intercalating pollutants in aqueous solution. These results suggested that the UV-irradiated DNA film was applicable as a functional material for medical, engineering and environmental sciences.

Solubility, tensile, and color properties of modified soy protein isolate films.

Protein solubility (PS) values of different soy protein isolate (SPI) films were determined in water, 0.01 N HCl, 0.01 N NaOH, 4 M urea, and 0.2 M 2-mercaptoethanol. Tensile and color (L, a, and b values) properties of films also were determined. Control films were cast from heated (70 degrees C for 20 min), alkaline (pH 10) aqueous solutions of SPI (5 g/100 mL of water) and glycerin (50% w/w of SPI). Additional films were cast after incorporation of dialdehyde starch (DAS) at 10% w/w of SPI or small amounts of formaldehyde in the film-forming solutions. Also, control film samples were subjected to heat curing (90 degrees C for 24 h), UV radiation (51.8 J/m(2)), or adsorption of formaldehyde vapors. PS of control films was highest (P < 0.05) in 2-mercaptoethanol, confirming the importance of disulfide bonds in SPI film formation. All treatments were effective in reducing (P < 0.05) film PS in all solvents. Both DAS and adsorbed formaldehyde rendered the protein in films practically insoluble in all solvents. Adsorption of formaldehyde vapors and heat curing also substantially increased (P < 0.05) film tensile strength from 8.2 to 15.8 or 14.7 MPa, respectively. However, heat curing decreased (P < 0.05) film elongation at break from 30 to 6%. Most treatments had small but significant (P < 0.05) effects on b color values, with DAS-containing films having the greatest (P < 0. 05) mean b value (most yellowish). Also, DAS-containing, heat-cured, and UV-irradiated films were darker, as evidenced by their lower (P < 0.05) L values, than control films. It was demonstrated that PS of SPI films can be notably modified through chemical or physical treatments prior to or after casting.

Real-time monitoring of laser photochemical reactions of polyvinylchloride

The formation of conjugated double bonds in polyvinylchloride (PVC) films by ultraviolet (UV) irradiation is analyzed using an in situ laser-monitoring technique we have developed to measure changes in transmittance of thin UV-irradiated PVC films. Conjugated polyenes of different lengths are produced by laser irradiation at 193 and 248-nm wavelengths. This technique promises to have broader applications in the study of polymer reaction mechanisms and kinetics.

Surface changes brought about by corona discharge treatment of polyethylene film and the effect on subsequent microbial colonisation

Microbial colonisation of synthetic plastic films is normally slow, which affects the total period of biodegradation. Correlation between the modified surface condition and the ability for microorganisms to colonise low-density polyethylene (LDPE) film was studied. Corona discharge treatment was applied to obtain enriched and activated surface condition of LDPE film. It was found from water contact angle and FTIR spectrum evaluations that surface energy was significantly increased due to production of free radicals. Stabilised oxidised LDPE surface was also obtained by further exposure to the corona which gave more suitable condition for subsequent colonisation. Results were compared with UV irradiated (photo-oxidised) LDPE films. Colonisation of corona discharged and UV treated LDPE films were tested in the laboratory environment using known fungal isolates and in a natural compost environment. More active microbial colonisation was observed in all cases for corona discharged and UV treated LDPE films. Far longer UV exposure was required to have the same physicochemical and biological effect as the corona discharge treatment.

Effect of AgNO 3 filling and UV-irradiation on the structure and morphology of PVA films

Polyvinyl alcohol films, with various AgNO 3 filler mass fractions (≤5%), were prepared. The structural and morphological variations, due to filling and UV-irradiation, were investigated using the following techniques; differential scanning calorimetry (DSC), UV/VIS optical absorption spectroscopy, X-ray diffraction and scanning electron microscopy (SEM). Two different crystalline phases (one is due to the PVA matrix and the other is attributed to the PVA–Ag + chelates) were detected besides the PVA amorphous phase, for the non-irradiated and the UV-irradiated (for 4 and 6 h) films. The PVA–Ag + chelates disappeared at 2 h UV-irradiation. It is implied that the structural morphology changes vastly due to the changes in filling level and/or UV-irradiation time. The observed morphological patterns were discussed.

Acid Proliferation Processes of 3-Phenyl-3,3-ethylenedioxypropyl Sulfonates in Photosensitive Polymer Films Leading to “Air Infection”

The thickness of UV-irradiated films of poly[p-(tert-butoxycarbonyloxy)styrene] and poly(tert-butyl methacrylate) containing a photoacid generator as a chemically amplified photoresist was reduced by the deprotection of the side chain residues as a result of the acidolysis reaction catalyzed by a photogenerated acidic species. It was observed that the reduction of film thickness is spread laterally on a millimeter scale to unexposed areas upon heating in the presence of 3-phenyl-3,3-ethylenedioxy-1-propyl p-toluenesulfonate as an acid amplifier that displays the autocatalytic acidolysis referred to as acid proliferation. The enlargement of areas showing the thickness reduction was suppressed effectively by covering the films with a glass plate or a polymer film. This observation suggested that the acidolysis reaction of the films is caused predominantly by the migration of acid molecules originated from the acid amplifier through the air. This was confirmed by the transfer of acid molecules to another aci...

UV-Induced Reaction Kinetics of Dilinoleoylphosphatidylethanolamine Monolayers

The UV-induced reactivity of dilinoleoylphosphatidylethanolamine (DLiPE) Langmuir and Langmuir-Blodgett films has been studied by in situ measurements of the changes in the mean molecular area, UV-vis and Fourier transform infrared spectroscopy, and atomic force microscopy (AFM). Optimum orientation and packing density of the DLiPE molecules in the monolayer were achieved by adding uranyl acetate to the subphase. A first-order reaction kinetic model was successfully fitted to the experimental reaction kinetics data obtained at a surface pressure of 30 mN/m. Topographical studies of LB films by AFM were performed on bilayer structures as a function of subphase composition and UV irradiation time. The orientational effect of the uranyl ions on the monolayer molecules was observed as an enhanced homogeneity of the freshly prepared monomeric LB films. However, the long-term stability of these films proved to be bad; clear reorganization and loss of a true monolayer structure were evidenced by the AFM images. This instability was inhibited for the UV-irradiated films, indicating that the UV irradiation gave rise to a cross-linked structure.