• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.312-314
• /
• 2009

We have fabricated pentacene based organic thin film transistors (OTFTs) with formulated poly[4-vinylphenol] (PVP) gate dielectrics. The gate dielectrics is composed of PVP, poly[melamine-coformaldehyde] (PMF) and photo-initiator [1-phenyl-2-hydroxy-2-methylpropane-1-one, Darocur1173]. By adding small amount (1 %) of photo-initiator, the cross-linking temperature is lowered to $115^{\circ}C$, which is lower than general thermal curing reaction temperature of cross-linked PVP (> $180^{\circ}C$). The hysteresis and the leakage current of the OTFTs are also decreased by adding the PMF and the photoinitiator in PVP gate dielectrics.

• Proceedings of the Korean Fiber Society Conference
• /
• 1996.10a
• /
• pp.468-472
• /
• 1996

A series of UV-curable polyurethane acrylate ionomer were synthesized from isophorone diisocyanate(IPDI), poly(tetramethylene ether glycol)(PTMG), 2,2-bis(hydroxymethyl)propionic acid (CMPA), triethylamine(TEA), 2-hydroxy ethyl acrylate (HEA), and dibutyl tin dilaurate (DBT) as a catalyst. 2,2-dimethoxy-2-phenyl acetophenone(DMPAP) was used as a photoinitiator. The films of UV-cured polyurethane acylate ionomer were prepared by casting the formulated materials onto a glass plate at room temperature and cured using a medium pressure mercury lamp (80 W/cm, max = 365nm). Effects of DMPA content, molecular weight of PTMG and degree of neutralization on the properties were invesigated. It is found that the storage modulus increased with increasing DMPA content. The glass transition temperature of sample A shifted to higher temperature as the content of DMPA was increased. Tensile modulus also increased with increasing DMPA content. Modulus and Tg decreased with increasing molecular weight of PTMG form 650 to 2000. With increasing the degree of nutralizaion, ionomers exhibited improved modulu.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.11 no.1
• /
• pp.17-29
• /
• 1993

As inverstigating the influence of monomers and photoinitiator in the polymerization rate of photopolymerization by using IR spectroscopy, photopolymerizations initiated by ultraviolet radiation are characterized by the presence of an autoacceleration in the polymerization rate as the reaction proceeds. The conversion for the end of the autoacceleration varies considerably depending on the monomer and reaction condition which determines coil size and viscosity. In UV curable systems, the autoacceleration begins at only a few percent conversion and continues to 40% in HEA solution and 60% conversion in EHA solution. The polymerization ate in HEA solution increased as follow; DMHA > HCPK > DMPA and could be explained by the interaction between the initiating radical and HEA monomer and the size of the photodissociated radical of initiator. But the tendency of autoacceleration in EHA solution is almost independent on initiator.

• Macromolecular Research
• /
• v.16 no.2
• /
• pp.128-133
• /
• 2008

Several dual-curable acrylic pressure-sensitive adhesives (PSA) were synthesized by the radical polymerization of acrylic monomers containing benzophenone, hydroxyl, and alkyl groups. The optimum extent of UV-induced cure was determined by varying the content of the benzophenone groups (the photoinitiator) from 0.5 to 1.5 wt%. The weight average molecular weight of the polymers obtained ranged from 300,000 to 700,000 amu. The coated pressure-sensitive adhesives were cured either by short UV exposure to induce the grafting of acrylic polymers, or by heating for 6 hat $60^{\circ}C$ to promote the reactions between the polyisocyanates and hydroxyl groups. The dual-curing behavior was determined by monitoring both processes quantitatively by infrared spectroscopy. The developed dual-curable acrylic pressure-sensitive adhesives were found to compensate for the limitations in UV-induced curing of thick coatings.

• Macromolecular Research
• /
• v.16 no.2
• /
• pp.149-154
• /
• 2008

UV-curable electrolytes inks were prepared by dissolving [2-[(methacryloyloxy)ethyl]dimethyl]propylaminium bromide (MEPAB), 1,5-[bis(2-methacryloxyethyl)dimethyl ammono]penthane dibromide (MDAPD), hexafunctional reactive oligomer (SP1013), trimethylolpropane triacrylate (TMPTA) and a photoinitiator in methanol/2-methoxyethanol. The compositions of the electrolyte inks were MEPAB/MDAPD/SP1013/TMPTA=6/24/17.2/12.8, 15/15/17.2/12.8 and 24/6/17.2/12.8. Humid-membranes were deposited on a gold electrode/alumina electrode using an ink-jet printer equipped with a UV lamp followed by immediate UV curing. The humidity-sensing characteristics including hysteresis, frequency and temperature dependence, response time and water durability were estimated.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.263.2-263.2
• /
• 2013

We report a systematic investigation of a set of macrophotoinitiators for use in polymerization-based signal amplification. To test the dependence of photopolymerization responses on the number of photoinitiators localized per molecular recognition event, we gradually increased the number of photoinitiator molecules coupled to a scaffold macromolecule. Macrophotoinitiators constructed with an average of 7 to 168 photoinitiators per polymer with the goals of quantifying the relationship between the number of initiators per binding event and the degree of amplified colorimetric readout. To evaluate the capacity of the macrophotoinitiators to detect molecular recognition, neutravidin was coupled to these molecules to recognize biotin-labeled DNA immobilized on biochip test surfaces. Fluorescein macroinitiators are found to be useful in detecting molecular recognition above a threshold of initiators per polymer. Above this threshold, increasing the number of initiators per macroinitiator resulted in increased signal strength.

• Journal of Integrative Natural Science
• /
• v.12 no.2
• /
• pp.29-34
• /
• 2019

In dental resin cement studies, viscosity is also an important factor in the adhesion of tooth defects and implants. This study used BisGMA and HPMA as the main ingredients, triethylene glycol dimethacrylate (TEGDMA) as a diluent, and benzoyl peroxide (BPO) as a photoinitiator. The physical properties of graphene oxide used as an additive for functionality were evaluated, and its use as a dental resin cement material was investigated.The rupture strength has the tendency to increase along with the increase of the ratio of graphene oxide that was added, which seemed to reflect the effect of the high strength property of graphene oxide. The flexural strength also has the tendency to increase when about 0.5% of graphene oxide was added the same as the increase of rupture strength.When graphene oxide was added, according to viscosity use, the utilization as high-quality dental resin cements will increase.

• Korean Journal of Materials Research
• /
• v.32 no.4
• /
• pp.193-199
• /
• 2022

In this study, lenses are fabricated using various nanomaterials as additives to a silicone polymer made with an optimum mixing ratio and short polymerization time. In addition, PVP is added at a ratio of 1 % to investigate the physical properties according to the degree of dispersion, and the compatibility with hydrophobic silicone and the possibility of application as a functional lens material are confirmed. The main materials are SIU as a silicone monomer, DMA, a hydrophilic copolymer, EGDMA as a crosslinking agent, and 2H2M as a photoinitiator. Holmium (III) oxide, Europium (III) oxide, aluminum oxide, and PVP are used. When Holmium (III) oxide and Europium (III) oxide are added based on the Ref sample, the characteristics of the lens tend to be similar overall, and the aluminum oxide shows a tendency slightly different from the previous two oxides. This material can be used as a silicone lens material with various nano oxides and polyvinylpyrrolidone (PVP) acting as a dispersant.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.45 no.1
• /
• pp.12-16
• /
• 2022

Di-tyrosine photo-crosslinking of silk fibroin (SF) is recently highlighted as a biocompatible hydrogel fabrication process, because this method does not need potentially harmful chemical species. However, the resulting crosslinking density is often insufficient to obtain a mechanically stiff hydrogel unless additional oxygen is provided during the reaction. In this study, we proposed a combinational crosslinking method to form an SF hydrogel via the di-tyrosine photo-crosslinking with riboflavin (photoinitiator) and physical interaction of SF chains. In the UV light-irradiated SF solution, small particles formed and these particles promoted β-sheet formation of SF molecules, resulting in quick gelation. The di-tyrosine photo-crosslinking produced nuclei that might trigger regular assembly of SF molecules in high temperature condition. Conclusively, this process would contribute to a development of biocompatible hydrogel fabrication for biomedical uses of SF hydrogels.

• Applied Chemistry for Engineering
• /
• v.24 no.5
• /
• pp.499-506
• /
• 2013

As the usuage of tempered glass for touch panel increased rapidly with the development of industry, the amount of UV curable coating solution used to protect glass surfaces during a tempered glass manufacturing process increased as well. The UV curable coating has advantages compared to thermal curing such as shortened curing time and non-solvent. Appropriated polymer and monomer were used as an acid polymer to grant an alkali peeling ability. The monomers were 2-hydroxyl methylacrylate, 1,6-hexanediol diacrylate and dipentaerythritol hexaacrylate which have acryl groups of 1, 2, and 6, respectively. The combination of three different types of photoinhibitors were used and bisphenol A epoxy diacrylate was used as an oligomer. In this study, experiments were carried out by controlling the amount of photoinitiator, oligomer, and additive while maintaining the constant content of the acid polymer and the acrylic monomer. The changes in physical properties according to the additive content were investigated. It was found that the combination of photoinitiators was necessary to achieve the hardness above 4H and it was possible to control the delamination type of the coating film from a sheet to pieces by the addition of TPO as an initiator. The increase in oligomer contents increased the hardness and adhesiveness alongside dissection time. Talc content of 20 wt% showed the best results.