• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.28-30
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• 2008

Poly(ethylene oxide)(PEO) of molecular weight of 300,000 was crosslinked by exposure to UV irradiation. Photochemical crosslinking of PEO occurred by UV irradiation and the presence of benzophenone in the film which acts as a hydrogen-abstracting agent. Percent conversion of the polymer into gel as well as water absorbency were investigated gravimetrically. Gel fraction and water absorbency of PEO films increased with increasing UV energy. In case of photocrosslinked PEO films with benzophenone, gel fraction increased up to about 90%. The thermal behavior of crosslinked PEO films was studied by thermogravimetric analysis. The maximum decomposition temperature increased with increasing UV energy and benzophenone concentration.

• Bulletin of the Korean Chemical Society
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• v.24 no.4
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• pp.441-445
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• 2003

We synthesized three copolymers bearing photochromic spiropyran dye and chalcone moiety in the side chain for studying the dynamic properties of their photochromism. They contain methacrylate-spiropyran (MAspiropyran) and methacrylate-chalcone (MA-chalcone) with the different concentration. The photosensitivity of the newly synthesized copolymers was investigated by using UV-Vis absorption spectroscopy. We observed photodimerization and photochromic behavior under UV irradiation at the same time. The effect of photocrosslink on the rate and stability of photochromism in three copolymers was considered in this study. This study might be helpful to design photochromic materials for irreversible optical memory by virtue of photocrosslinking reaction.

• Macromolecular Research
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• v.13 no.3
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• pp.180-186
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• 2005

A novel bifunctional dye composed of spirobenzopyran and a cinnamoyl moiety was prepared and its photochromic behavior under the illumination of monochromatic UV light was investigated. This colorless bifunctional dye exhibits typical photochromism in both the film and in solution, through the structural and geometrical transformation from spirobenzopyran to merocyanine accompanied by a photocrosslinking reaction between the cinnamoyl moieties. Two kinds of photochemical reaction were selectively achieved by irradiation with monochromatic UV light at wavelengths of 275 and 365 nm, respectively. The effect of the selective photochemical reaction on the photochromism of the dye and its decaying behavior was investigated.

• Macromolecular Research
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• v.9 no.5
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• pp.253-258
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• 2001

Crosslinked poly(ethylene glycol)s (PEGs) were prepared by ultraviolet irradiation of low molar mass, liquid PEGs in the presence of benzophenone (BP) as a photoinitiator. The networks obtained have been characterized by DSC, IR, and contact angle measurements, and their water absorption and equilibrium swelling have been examined. The percent of gel formed and degree of swelling of the networks in water were dependent on the amount of BP in the reaction mixture, irradiation time and molar mass of PEG. Gel fraction yield exceeded 84%, and equilibrium swelling in water varied from 49 to 244%.

• Journal of Photoscience
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• v.6 no.3
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• pp.145-151
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• 1999

The use of O-carbamoyloximes as photobase generators was investigated. $\alpha$-Meth-ylbenzilydeneamino phenylcarbamate(2a) and $\alpha$-methyl benzilydeneamino cyclohexylcarbamate(2b) were prepared by the reaction of phenyl or cyclohexyl isocyanates with acetophenone oxime , respectively. Aniline, phenylhydrazine and N, N'-diphenylhydrazine were detected in thephotolysis of 2a and cyclohexylamine and cyclohexylhydrazine in the photolysis of 2b. A monomer having pendant carbamoyloxyimino groups (BGM) was prepared by the reaction fo methancryloyloxyethyl iocyanate with acetophenone oxime, and copolymerized with styrene. The BGM copolymer films turned insoluble on UV irradiation, and the degree of insolubilizationwas increased by post-baking. The photocrosslinking was thought to be due to coupling of resulting pendant aminyl radicals, and the thermal crosslinking was due to association of resulting amino and hydrazino groups by hydrogen bonding. The introduction of epoxy groups into polymer increased the degree of thermal crosslinking by post-baking.

• Polymer(Korea)
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• v.36 no.1
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• pp.76-87
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• 2012

Three kinds of hydroxypropyl cellulose (HPC) derivatives, [6-{4-(4-cyanophenylazo)phenoxy}]hexyloxypropyl celluloses (CAHPCs) with degree of etherification (DET) ranging from 0.4 to 3, fully substituted acrylic acid esters of HPC (HPCA) and CAHPCs (CAHPCAs) were synthesized. The crosslinked HPCA (HPCAG) and CAHPCAs (CAHPCAGs) were also prepared by exposing thermotropic mesophases of HPCA and CAHPCAs to UV light. Both CAHPCs and CAHPCAs with DET ${\leq}$ 1.2, as well as HPC and HPCA, formed enantiotropic cholesteric phases whose optical pitches(${\lambda}_m$'s) increase with temperature, wheras both CAHPCs and CAHPCAs with DET ${\geq}$ 1.4 showed monotropic nematic phases. CAHPCAGs with DET ${\leq}$ 1.2, as well as CAHPCAs with DET ${\leq}$ 1.2, exhibited reflection colors in a wide temperature range. On the other hand, CAHPCAGs with DET ${\geq}$ 1.4, as well as CAHPCAs with DET ${\geq}$ 1.4, showed Schileren textures typical of nematic phase, indicating that the liquid crystalline structure is virtually locked upon photocrosslinking. The isotropization temperatures($T_i$'s) of both CAHPCAs and CAHPCAGs decreased with increasing DET. The $T_i$ of CAHPCAG, however, was higher than that of CAHPCA at the same DET. Moreover, the temperature dependence of ${\lambda}_m$ of CAHPCAGs was much weaker than that of CAHPCAs.

• Textile Coloration and Finishing
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• v.21 no.4
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• pp.33-38
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• 2009

Poly(vinyl acetate) films containing benzophenone were photocrosslinked by continuous UV irradiation.UV irradiation of PVAc film containing 5% benzophenone induced bulk crosslinking of the polymer indicated by 84.1% of gel fraction after ethyl acetate extraction. The crosslinking was attributed to the recombination of tertiary polymer radicals generated upon UV irradiation, which was enhanced by the hydrogen abstraction of benzophenone. Also the UV irradiation resulted in scission of ester linkage and photooxidation of PVAc surface, which was verified by ATR and zeta potential analysis, implying that the PVAc surface became more polar and hydrophilic. The zeta potential proportionally increased from +4.5mV to -26.8 mV with increasing UV irradiation. Also the surface energy of the PVAc film increased with higher UV irradiation upto 56.5 $mJ/m^2$ by the enhanced Lewis acid/base component with larger contribution of Lewis acid parameter. Accordingly the crosslinked PVAc showed higher thermal stability with increasing UV energy.

• Macromolecular Research
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• v.12 no.4
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• pp.352-358
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• 2004

For their application as one-component photoresists, we prepared epoxy terpolymers containing oxime-urethane and benzophenone groups by the radical polymerization of glycidyl methacrylate (GMA), metha-cryloxyethyl benzophenoneoxime urethane (MBU), and N-(4-benzoyl)phenylmaleimide (BPMI). The terpolymer composition was optimized to provide the most photosensitive photoresist. The photo-decomposition reaction of the oxime-urethane groups in the terpolymer was monitored by UV absorption spectroscopy, and the photo-crosslinking reaction of the epoxy terpolymer was observed by measuring the normalized thickness. The photosensitivity of the epoxy terpolymer increased as the amount of BPMI and MBU units increased up to 16 and 24 mol%, respectively. Among the terpolymers we prepared, terpolymer T-II(contents of GMA, MBU, BPMI are 75, 19, 6.1 mole%, respectively) exhibited the highest photosensitivity ( $D_{c}$ $^{0.5}$ = 430 mJ/$\textrm{cm}^2$) and had a moderate contrast (${\gamma}$$^{p}$ = 1.23). Negative-tone micropatterns having a line width of ca. 10 ${\mu}{\textrm}{m}$ were obtained by developing the system with chloroform.m.

• BioChip Journal
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• v.12 no.4
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• pp.280-286
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• 2018

Hydrogel scaffolds composed of multiple components are promising platform in tissue engineering as a transplantation materials or artificial organs. Here, we present a new fabrication method for implementing multi-layered macroscopic hydrogel scaffold composed of multiple components by controlling height of hydrogel layer through precise control of ultraviolet (UV) energy density. Through the repetition of the photolithography process with energy control, we can form several layers of hydrogel with different height. We characterized UV energy-dependent profiles with single-layered PEGDA posts photocrosslinked by the modular methodology and examined the optical effect on the fabrication of multi-layered, macroscopic hydrogel structure. Finally, we successfully demonstrated the potential applicability of our approach by fabricating various macroscopic hydrogel constructs composed of multiple hydrogel layers.

• Polymer(Korea)
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• v.35 no.1
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• pp.87-93
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• 2011

We developed a fluorene-containing multifunctional binder polymer for LCD color filter resist, and employing the binder polymer, carbon black based black photoresist (CBR) was prepared in order to apply it to the black matrix (BM). To obtain the multifunction of the binder polymer, we synthesized bisphenol fluorene epoxy acrylate-containing unsaturated polyester and identified the binder polymer structure with $^1H$ NMR, GPC and FTIR. The corresponding BFEA-polyester binder polymer was compared with the commercially available acryl binder toward the application to the CBR. From the BM lithography test, we found that the synthesized BFEA-polyester binder had better photocrosslinking capability and alkali solubility. In addition, the newly developed binder gave a good process margin, good resolution and adhesion property on a glass substrate.