Polymer UV Research Articles

Fabrication of polymer waveguides using a molding process

Polymer waveguides are successfully fabricated by a simple method, which is incorporated with a lithography-galvanic (LIGA)-like and micromolding process. The refractive index of the UV polymer used in these experiments is changed by an extremely low electric field. The measured propagation loss is 0.32 dB/cm for 1.3 µm and 0.30 dB/cm for 1.55 µm. This process is easy, simple, and suitable for mass production.

A New Method to Fabricate Polymer Waveguides

Polymer waveguides were successfully fabricated by a new method, which was incorporated with a micromolding process. The refractive index of the UV polymer used in these experiments was changed by an extremely low electric field. The experiment of the near field measurement with end fire coupling had shown that the light had been totally restricted inside the core layer of the waveguide. This process is easy and simply for mass production of any shape of polymer waveguides.

Pixel-Isolated Liquid Crystal Mode for Flexible Display Applications

We developed a new device using anisotropic phase separation from liquid crystals (LCs) and polymer composite materials using UV intensity variation and polymer wetting properties for flexible display applications. In the device, LC molecules are isolated in pixels where LCs are surrounded by interpixel vertical polymer walls and horizontal polymer films on the upper substrate. This device shows very good mechanical stability against external pressure. The electro-optic characteristics and the mechanical stability of the device are discussed in view of flexible display applications.

P‐92: Flexible Displays Using Pixel Isolated LC Mode

AbstractWe developed a new device structure using anisotropic phase separation from liquid crystal (LC) and polymer composite materials using UV intensity variation and polymer wetting properties. In the device, the LC molecules are isolated in pixels where LCs are surrounded by the inter‐pixel vertical polymer walls and the horizontal polymer films on the upper substrate. These devices show very good mechanical stability against external pressure. The electro‐optic characteristics and the mechanical stability of the devices are discussed in view of the flexible display applications.

Synthesis of a novel block copolymer poly(ethylene oxide)‐block‐poly(4‐vinylpyridine) by combination of anionic ring‐opening and controllable free‐radical polymerization

AbstractThe block copolymer poly(ethylene oxide)‐b‐poly(4‐vinylpyridine) was synthesized by a combination of living anionic ring‐opening polymerization and a controllable radical mechanism. The poly(ethylene oxide) prepolymer with the 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy end group (PEOT) was first obtained by anionic ring‐opening polymerization of ethylene oxide with sodium 4‐oxy‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy as the initiator in a homogeneous process. In the polymerization UV and electron spin resonance spectroscopy determined the 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy moiety was left intact. The copolymers were then obtained by radical polymerization of 4‐vinylpyridine in the presence of PEOT. The polymerization showed a controllable radical mechanism. The desired block copolymers were characterized by gel permeation chromatography, Fourier transform infrared, and NMR spectroscopy in detail. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4404–4409, 2002

Influence of Polymer Matrixes on the Photophysical Properties of UV Absorbers

The copolymerization parameters for monomer pairs of the copolymerizable UV absorbers MA-TIN 1 (2-[2-hydroxy-3-tert-butyl-5-(O-[2-hydroxy-3-(2-methylpropenoyloxy)-propyl]-2-carbonyloxyethyl)phenyl]benzotriazole) and MA-TZ 1 (2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(2-hydroxy-3-[2-methylpropenoyloxy])propoxyphenyl]-1,3,5-triazine) with styrene and methyl methacrylate were determined. The UV absorbers were present to a higher extent in the copolymers than they are when simply present as mixtures of monomeric UV absorbers in the monomer feed. At higher temperatures, the radiationless deactivation from the excited proton-transferred singlet state becomes more efficient for the UV absorbers physically admixed to the polymer than for the respective polymeric UV absorbers. MA-TZ 1 embedded in poly(methyl methacrylate) shows an equal increase of phosphorescence intensity with UV irradiation time as the decrease of the proton-transferred fluorescence. By combining fluorescence and phosphorescence measurements it becomes possible to estimate the proportion of UV stabilizer molecules with an intermolecular hydrogen-bridge to poly(methyl methacrylate) and which are not suitable for light protection of polymers at room temperature. At low pressure and temperature, the increase of light-induced phosphorescence was delayed. This “phosphorescence induction” phenomenon can be put down to the free volume of polymer matrixes, in which various UV absorbers have been incorporated. The emission spectroscopic results are applicable to products which are customary in trade, as shown by investigations on a clear coat binder system.

Advanced Micro Stereolithography with Multi UV polymers

We have developed a new type of micro stereolithography to make a microstructure with multiple UV polymers. This process provides us total-polymer-based microdevices (Polymer MEMS) by ingeniously combining various UV polymers with different characteristics: refractive index, conductivity, Young's modulus. For example, the difference in refractive index can be utilized many optical devices like optical waveguides, photonic crystals, etc. Actually we succeeded to fabricate optical waveguides with two kinds of UV polymers having different refractive indexes. The fabrication system consists of laser scanning system, roller pumps to supply UV polymers, a cylinder for the store of UV polymers. We can easily switch several UV polymers by choosing roller pumps during fabrication process. This process opened Polymer MEMS technology giving great contribution to micro optics and micro-chemical devices.

Biochemical IC Chip toward Artificial Cellular Device.

The Biochemical IC using new three dimensional micro fabrication technique has been developed by the author's group. The concept of the Biochemical IC proposed by Ikuta in 1993 is completely different from the silicon based micro-TAS (Total Analysis Systems). The biochemical IC is based on modular concept like a today's IC/LSI family. Each biochemical IC chip in disk (or cell) shape contains various kind of functional component such as multiple micro valves, micro chemical condensers (concentrators) and micro reactors. Another uniqueness of this research is using new 3D micro fabrication process to make a hybrid structure suitable for real three dimensional integrated micro fluidic devices. Author's original IH process (micro stereo lithography) was up-graded to make composite structures consisting of UV polymer and other materials. Finally, total system made of various biochemical IC chips were constructed and controlled for many applications.

Polymeric photoinitiators having benzoin methylether moieties connected to the main chain through the benzyl aromatic ring and their activity for ultraviolet-curable coatings

New polymeric UV photoinitiators, bearing the benzoin methyl ether moiety linked to the side chain through the 4′ position, were synthetized by radical homopolymerization of the corresponding monomers, 4′-methacryloyloxy benzoin methyl ether and 4′-methacryloyloxy α-methyl benzoin methyl ether, prepared in turn after a thorough investigation of synthetic methods. For comparison, low molecular weight structural models of the repeating co-units of the polymers having the pivaloyloxy group linked to the 4′ position of the benzoin methyl ether moiety were also prepared. All polymeric and model compounds were fully characterized and employed in the photoinitiated polymerization and crosslinking of a standard acrylic formulation for clear UV curable coatings. The photoinitiating activity of these systems, measured by microwave dielectrometry, indicates a higher cure fastness for the model compounds with respect to the corresponding polymeric derivatives, and such a behaviour is tentatively interpreted in terms of the fragmentation mechanism of the benzyl methyl ether radicals formed on α-photocleavage of the benzoin moiety.

Multifunctional Polymeric UV Absorbers for Photostabilization of Wool

Photoyellowing of wool can be reduced up to 50% when polymeric UV absorbers with (meth)acrylate backbone are applied. UV absorbers derived from hydroxyphen ylbenzotriazole are most effective. Degradation of photolabile amino acids like tryp tophan and formation of cysteic acid are reduced. The mechanical properties of wool measured by abrasion resistance and bundle tensile strength tests improve with poly meric multifunctional UV absorbers. Resistance to washing of the polymers on wool fibers improves as compared with a low molecular weight stabilizer. Despite additional hydrocarbon and fluorinated side groups, the water repellent effect of polymeric UV absorbers is weak.

Preparation and characterization of polymers with pending UV‐absorber groups. I. Polymers based on polydimethylsiloxane

AbstractThe hydrosilylation reaction using dichloro(dicyclopentadiene) platinium (II) as catalyst is carried out to synthesize polymeric UV absorbers with polysiloxane backbone. An almost quantitative addition of vinyl groups of the UV absorber (benzophenone) to silane groups is observed. The IR spectra indicate the qualitative results of the reaction, whereas the 1H‐NMR spectra allow the following of the reaction quantitatively. Low glass transition temperatures are observed by DSC. UV spectroscopy shows that the extinction coefficient and spectra of the UV absorbers are hardly affected by the polymer analogous reaction. © 1994 John Wiley & Sons, Inc.

Reactivity ratios and UV spectral characteristics of copolymers of vinyl or isopropenyl derivatives of 2-(2-hydroxyphenyl)-2H-benzotriazoles

The preparation of polymeric UV stabilizers by copolymerization of polymerizable UV stabilizers like 2-(2-hydroxy-5-vinylphenyl)-2H-benzotriazole (2H5V) and 2-(2-hydroxy-5-isopropenylphenyl)-2H-benzotriazole (2H5P) with styrene (S), methyl methacrylate (MMA), and butyl acrylate (BA) was studied. Copolymerization parameters for six pairs of monomers, i.e. 2H5V-S, 2H5V-MMA, 2H5V-BA, 2H5P-S, 2H5P-MMA, and 2H5P-BA and UV spectra of the 2H5P copolymers were determined. The effect of stiffness of the polymer chain on UV spectra of copolymers studied is discussed.

Synthesis and Study of Polymeric Ultraviolet Absorbers. II

Abstract Polymeric UV absorbers have been prepared by free-radical solution copolymerization at 75°C of methyl methacrylate and 2-hydroxy-4-methacryloyloxybenzophenone monomers at low conversion (around 10%). The composition of the copolymers was determined by UV, IR, and NMR studies. The molecular weight was estimated by GPC. The reactivity ratios were determined by several methods. Viscosity was used to study the effect of copolymer composition and solvents. The copolymers were also analyzed by TGA and DSC, and DSC was used to study the effect of copolymer composition on Tg.

Frying performance of palm oil liquid fractions

AbstractPalm oil liquid fractions were used as frying media in household and industrial fryers and were compared to standard edible oils and fats, such as soybean, groundnut, sunflower, rapeseed and tallow. The analytical evaluation covered free fatty acids, viscosity, smoke and flame points, oxidized fatty acids, nonelution material (NEM), UV differential spectra, polymers and foam index. These values measure the extent of the oil degradation, i.e., oxidation, hydrolysis, splitting and polymerization. Moreover, they were combined with other analytical procedures (fatty acid composition, keeping qualities such as the time necessary for an oxygen‐absorbing sample to reach a ‐0.5 psi pressure in a closed system) in order to have a large analytical control during the frying processes. The data collected show the suitability of edible oils and fats for frying purposes and indicate that palm oil liquid fractions perform satisfactorily as frying media. They have low degradation and produce fried foods with acceptable keeping qualities.

Polymeric UV Absorbers of the 2-Hydroxybenzophenone Type. III. Tertiary Amine Catalyzed Polymerization of 2-Hydroxy-4(2,3-epoxypropoxy)benzophenone

Abstract The tertiary amine catalyzed polymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone (HEPBP) in melt and o-xylene solution was studied. UV, IR, and NMR spectra of the polymer thus obtained were evaluated and its molecular weight was determined. In order to elucidate the polymerization of HEPBP, the model reaction of 2-hydroxybenzophenone with 4-(2,3-epoxypropoxy)benzophenone at an equimolar ratio as well as the reaction of HEPBP with 2,4-dihydroxybenzophenone at a molar ratio of 2:1 was investigated. A reaction mechanism was suggested for the polymerization of HEPBP on the basis of the results obtained. According to this mechanism, a catalytic center originates during initiation, and that center affords phenoxyl anion by reacting with HEPBP. In the following step phenoxyl anion opens the epoxide ring and an alkoxide anion arises. The basic alkoxide anion is stabilized by a proton transfer of a phenolic group. The successive recurrence of these reactions results in the growth of the polymer c...

Polymeric UV absorbers of the 2‐hydroxybenzophenone type. II. On the mechanism of the polymerization of 2‐hydroxy‐4‐(2,3‐epoxypropoxy) benzophenone with phthalic anhydride

AbstractSimultaneously with the preparation of 2‐hydroxybenzophenone light stabilizers with a reduced extractability from polypropylene, the mechanism of the propagation reaction of 2‐hydroxy‐4‐(2,3‐epoxypropoxy) benzophenone with phthalic anhydride was studied under different concentrations and temperature conditions, with tert‐amines, potassium benzoate, and potassium hydroxide being used as catalysts. If the polymerization of epoxide with anhydride is performed in melt at 125°C, an alternating copolymer is formed whether an equimolar ratio or a molar excess of anhydride with respect to epoxide has been used. Provided epoxide is present in molar excess with respect to anhydride in the reaction system, some changes in ultraviolet absorption spectra are observed in comparison with the spectra of alternating copolymers which indicate that some undesirable reactions of the orthophenolic groups of benzophenone occur simultaneously with the catalyzed polyaddition reaction, and that the polymeric stabilizer is impaired.