• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.321-321
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• 2006

Aromatic diacetylenes form stable oligomeric diradicals when irradiated with UV light or heated at temperatures above their melting points. In this paper, the formation of stable diradicals is discussed, and the mechanism of polymerization in the presence of peroxide in solution, is discussed. The diphenyldiacetylene undergoes polymerization through coupling of diradicals, and not by the successive addition of radical species.

• 대한치과기공학회지
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• 제44권3호
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• pp.76-80
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• 2022

Purpose: The purpose of this study is to analyze the depth according to curing using photocurable resin for dental three-dimensional printing. Methods: A stainless mold with a height of 4 mm was prepared. Ultraviolet (UV) polymerization resin was injected into the mold. Photocuring was then performed for 5 minutes using a photopolymerizer, and the height was measured using a digital measuring instrument (first group). Second, light polymerization was also performed outside the mold for 5 minutes, and the height was measured using a digital measuring instrument. Third, light polymerization was further performed for 5 minutes, and the height was measured using a digital measuring instrument. Statistical analysis was performed with the Kruskal-Wallis test, which is a nonparametric test (α=0.05). Results: The third group had the largest measurement length, whereas the first group had the smallest. However, the difference between groups was not statistically significant (p>0.05). The color of the first group was different from that of the second and third groups. Conclusion: All of the 4-mm-thick photocured specimens had a curing reaction, but the part that was not directly irradiated with UV did not show its original color.

• 한국안광학회지
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• 제8권2호
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• pp.129-134
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• 2003

불포화 비닐 유도체의 다양한 반응성은 자유 라디칼의 사슬 중합반응을 거쳐 유도되어질 수 있으며, 열역학적으로 실행 가능한 고분자 중합을 수행할 수 있는 능력은 주어진 반응조건 항서 반응을 진행시킬 수 있는 적당한 속도에 의존한다. 따라서 반응이 일어날 수 있는 속도조건을 만들기 위해 중합 개시제와 촉진제가 주로 사용되고 있다. 빛의 흡수도는 Methyl Methacrylate(MMA)를 포함한 단지 몇 종류의 불포화 비닐 단량체들만이 가장 편리한 250nm~500nm 파장범위의 빛을 흡수할 수 있다고 알려져 있다. 또한 광학적, 전기적으로 독특한 성질을 가진 polysilanes은 세라믹의 전구물질, UV 광전저항, 광전도체 등으로 널리 사용되어 왔으며, hydrosilation 반응은 실리콘을 포함한 여러 가지 흥미로운 고분자를 만드는데 사용되고 있다 본 연구는 콘텍트렌즈 재료로 사용되는 고분자를 광 화학적 개시제의 작용을 통하여 공중합체와 단일 중합체로 합성하여 그 수율을 분석하였다. 그 결과 이러한 개시제들은 비닐 유도체들의 중하반응에서 경쟁적으로 또는 동시에 사슬 개시와 사슬 전이제로서 작용하고 있음을 보여 주었다.

• Membrane and Water Treatment
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• 제1권2호
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• pp.103-120
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• 2010

Surface modification of microfiltration and ultrafiltration membranes has been widely used to improve the protein adsorption resistance and permeation properties of hydrophobic membranes. Several surface modification methods for converting conventional membranes into low-protein-binding membranes are reviewed. They are categorized as either physical modification or chemical modification of the membrane surface. Physical modification of the membrane surface can be achieved by coating it with hydrophilic polymers, hydrophilic-hydrophobic copolymers, surfactants or proteins. Another method of physical modification is plasma treatment with gases. A hydrophilic membrane surface can be also generated during phase-inverted micro-separation during membrane formation, by blending hydrophilic or hydrophilic-hydrophobic polymers with a hydrophobic base membrane polymer. The most widely used method of chemical modification is surface grafting of a hydrophilic polymer by UV polymerization because it is the easiest method; the membranes are dipped into monomers with and without photo-initiators, then irradiated with UV. Plasma-induced polymerization of hydrophilic monomers on the surface is another popular method, and surface chemical reactions have also been developed by several researchers. Several important examples of physical and chemical modifications of membrane surfaces for low-protein-binding are summarized in this article.

• Bulletin of the Korean Chemical Society
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• 제23권1호
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• pp.35-40
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• 2002

Photoreaction of guest organic anions in layered organic-inorganic hybrid materials was investigated. The layered hybrids were synthesized by an anion-exchange reaction of $[LiAl_2(OH)_6]Cl{\cdot}yH_2O$ layered double hydroxide with aqueous (Z,Z)- and (E,E)-muconates under inert atmospheric condition, to give new organicinorganic hybrids of $[LiAl_2(OH)_6]_2[(Z,Z)-C_6H_4O_4]{\cdot}zH_2O$ and $[LiAl_2(OH)_6]_2[(E,E)-C_6H_4O_4]{\cdot}H_2O$, respectively. The basal spacings calculated by XRPD of intercalates indicate that muconate anions have almost vertical arrangements against the host $[LiAl_2(OH)_6]^+$ lattices in the interlayer of organic-inorganic hybrid materials. When UV light was irradiated on the suspension of $[LiAl_2(OH)_6]_2[(Z,Z)-C_6H_4O_4]{\cdot}zH_2O$, the (Z,Z)-muconate anions of the gallery space of hybrids were polymerized in the aqueous media while it was isomerized into more stable (E,E)-muconate in the methanollic suspension in the presence of catalytic amount of molecular iodine. All the products were characterized using elemental analysis, TGA, XRPD, FT-IR, $^1H$ NMR and $^{13}C$ CP-MAS NMR.

• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 춘계 총회 및 학술발표회
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• pp.99-101
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• 1998

1. Introduction : The conventional grafting polymerization technique requires chemically reactive groups on the surface as well as on the polymer chains. For this reason, a series of prefunctionalization steps are necessary for covalent grafting. The surface prefunctionalizational technique for grafting can be used to ionization radiation, UV, plasma, ion beam or chemical initiators. Of these techniques, radiation method is one of the useful methods because of uniform and rapid creation of active radical sites without catalytic contamination in grafted samples. If the diffusion of monomer into polymer is large enough to come to the inside of polymer substrate, a homogeneous and uniform grafting reaction can be carried out throughout the whole polymer substrate. Radiation-induced grafting method may attach specific functional moieties to a polymeric substrate, such as preirradiation and simultaneous irradiation. The former is irradiated at backbone polymer in vacuum or nitrogen gas and air, and then subsequent monomer grafting by trapped or peroxy radicals, while the latter is irradiated at backbone polymer in the presence of the monomer. Therefore, radiation-induced polymerization can be used to modification of the chemical and physical properties of the polymeric materials and has attracted considerable interest because it imparts desirable properties such as blood compatibility. membrane quality, ion excahnge, dyeability, protein adsorption, and immobilization of bioactive materials. Synthesizing biocompatible materials by radiation method such as preirradiation or simultaneous irradiation has often used $\gamma$-rays to graft hydrophilic monomers onto hydrophobic polymer substrates. In this work, in attempt to produce surfaces that show low levels of anti-fouling of bovine serum albumin(BSA) solutions, hydroxyethyl methacrylate(HEMA) was grafted polypropylene membrane surfaces by preirradiation technique. The anti-fouling effect of the polypropylene membrane after grafting was examined by permeation BSA solution.

• Macromolecular Research
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• 제15권1호
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• pp.74-81
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• 2007

A series of photoreactive mesogens based on chalcone were prepared and their morphological behavior and reactivity were studied according to a variable number of alkyloxy tail carbons. The linear ester compounds 3a-h comprised two chalcone units connected to a benzene ring through ester linkages. All linear ester compounds showed enantiotropic liquid crystalline phases. The X-ray diffractograms for the mesophases of compounds 3a-h showed a set of reflections in the small-angle region which consisted of more than three sharp diffraction peaks with d spacings in the ratio of 1:1/2:1/3, confirming the well defined smectic A structures of the compounds. Compounds 3a-h were considered to be bifunctional monomers due to the presence of two photoreactive chalcone groups. Upon UV irradiation, its polymerization proceeded through the [2+2] addition reaction between chalcone units in a stepwise manner. An image pattern was obtained by the photopolymerization of the liquid crystal of the compound (3h) with decyloxy tails through a photomask. The irradiated part became dark while the masked part remained birefringent under polarized optical microscopy, which was ascribed to the production via the UV irradiation of a polymer or a dimer having cyclobutane rings by [2+2] addition, which thereby disrupted the alignment of the molecules.

• Journal of Photoscience
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• 제7권4호
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• pp.131-133
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• 2000

A Styrene-derived polymer having pendent phenoxyanthraquinones for photochromism was prepared by AIBN-initiated radical polymerization. Syntgesus of the monomers was straightforward and the polymer was obtained in 65% yield. Photoinduced rearrangement from the “trans” quinone forms to the “ana” quinone forms readily occurred both in solution and in film when the polymer was irradiated with UV light.

• Elastomers and Composites
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• 제49권3호
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• pp.199-203
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• 2014

아크릴 단량체인 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA), isobornyl acrylate (IBOA)를 광중합을 통하여 3원 공중합체 시럽을 합성하였다. 이관능기 아크릴 단량체인 1,6-hexanediol diacrylate (HDDA), poly(ethylene glycol) diacrylate (PEGDA, Mn = 250, 575, 700)를 가교제로 사용하여 semi-IPN형 감압성 점착제 (Pressure sensitive adhesives; PSAs)를 UV-광가교 시켜 제조하였다. 가교제 변화에 따른 감압성 점착제의 점착특성, 저장탄성율, 그리고 광학특성을 고찰하였으며, 점착특성과 저장탄성율은 가교제의 화학구조와 분자량에 의존하였다. 광학특성은 모든 감압성 점착제에서 92.5 % 이상의 광투과도 (at 550 nm), 1.0 % 이하의 haze값, 0.3 이하의 색차계값을 보임을 확인하였다. 결과적으로 가교제의 종류에 영향을 받지 않음을 확인하였다.

• 폴리머
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• 제32권1호
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• pp.70-76
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• 2008

UV 조사방법으로 poly(ethersulfone) PES 막에 1,2,3,4-butanetetracarboxylic acid(BTCA)를 그래프트 공중합하고, 이를 아민화시켜 PES 음이온교환막을 합성하였으며, 이들의 구조 및 특성을 확인하였다. PES 음이온교환막의 그래프트율과 아민화율은 반응 시간에 따라 증가하였으며, 80분에서 최대 134%, 1.20 mmol/g이었다. PES 음이온교환막의 초기 열분해온도는 $400^{\circ}C$로 표면개질반응이 진행됨에 따라 감소하였다. PES 음이온교환막의 접촉각은 아민화율이 증가함에 따라 $68.1^{\circ}{\sim}40.2^{\circ}$로 감소하였으며, 함수율과 이온교환용량은 UV 조사시간이 증가함에 따라 80분까지 선형적으로 증가하였다. 또한 막의 평균 기공의 크기와 비표면적은 PES 막, PES-g-BTCA 공중합체막, PES 음이온교환막의 순이었으며, 평균기공 크기값은 624.8, 359.7, 138.5 ${\AA}$, 비표면적은 10.1, 9.7, 1.7 $m^2/g$이었다.