• 공업화학
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• 제31권6호
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• pp.697-700
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• 2020

본 연구에서는 석영 나노 결정의 합성과 특성 분석을 진행하였다. 비정질 실리카 나노 입자 전구체가 용해된 용액을 섭씨 250도 온도와 자가 압력의 온건한 열수 반응 하에서 석영 나노 결정을 성공적으로 합성하였다. 합성된 나노 결정의 화학적 조성과 구조 분석을 시행하였다. 알파 석영의 특징적인 고결정질 상의 나노 구조를 가지는 석영 나노 결정의 평균 크기는 반응 시간에 따라 407.5 에서 826.2 nm까지 비교적 좁은 범위에서 조정될 수 있음을 발견하였다. 본 연구를 통해 발견된 석영 나노 입자는 광전자, 센서, 및 충전식 배터리 소자의 기술 응용에 매우 중요한 잠재적 용도가 있을 것으로 사료된다.

• Macromolecular Research
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• 제15권2호
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• pp.114-128
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• 2007

Polyimides are one of the most important classes of polymers used in the microelectronics and photoelectronics industries. Because of their high thermal stability, chemical resistance, and good mechanical and electric properties, polyimides are often applied in photoresists, passivation and dielectric films, soft print circuit boards, and alignment films within displays. Recently, fully aliphatic and alicyclic polyimides have found applications as optoelectronics and inter layer dielectric materials, due to their good transparencies and low dielectric constants $(\varepsilon)$. The low molecular density, polarity and rare probability of forming inter- or intra-molecular charge transfers, resulting in lowering of the dielectric constant and high transparency, are the most striking characteristics of aliphatic polyimide. However, the ultimate end use of polyimides derived from aliphatic monomers is in their targeted applications that need less stringent thermal requirements. Much research effort has been exerted in the development of aliphatic polyimide with increased thermal and mechanical stabilities, while maintaining their transparencies and low dielectric constants, by the incorporation of rigid moieties. In this article, the recent research process in synthesizing fully aliphatic polyimides, with improved dimensional stability, high transparency and low $\delta$values, as well as the characterizations and future scope for their application in micro electric and photo-electronic industries, is reviewed.

• Journal of Information Display
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• 제6권4호
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• pp.1-5
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• 2005

Perylene-based pyrrolopyrone derivative (PPD) was synthesized via condensation reaction with perylenetetracarboxylic dianhydride and 1,2-phenylenediarnine as n-type channel material. The structure of PPD was characterized by spectroscopic methods such FT-IR and $^1H$-NMR. PPD exhibited high thermal stability ($T_{d5wt%}: 560^{\circ}C$) and was found to be soluble only in protonic solvents with high acidity such as methane sulfonic acid and trifluoroacetic acid. The PPD solution showed maximum absorption and emission at 601 and 628 nm, respectively. Thin film transistors were fabricated by vacuum deposition and solution casting method. The electron mobilities of the devices were achieved as high as $0.17{\times}10^{-6}cm^2/Vs$ for vacuum deposited device and $0.4{\times}10^{-6}cm^2/Vs$ for spin coated device, respectively.

• 폴리머
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• 제29권6호
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• pp.575-580
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• 2005

하이드록시 말단의 지방족 고차가지구조 폴리에스테르를 용융축합법을 이용하여 합성하였다. 말단의 하이드록시 그룹을 acryloyl chloride를 사용하여 비닐 말단으로 변환시켰으며, 말단변화에 따른 구조를 분석하고 분자량을 측정하였다. 비닐 말단의 지방족 고차가지구조 폴리에스테르는 점도가 높고 노란색의 투명한 액체이며, 하이드록시 말단의 지방족 고차가지구조 폴리에스테르에 비해 유리전이온도가 낮았다. 또한 비닐 말단으로 변형한 후에는 열안정성이 감소하였으며, 말단 작용기의 전환율 차이에 의해 불규칙적인 열분해거동을 보였다.

• 멤브레인
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• 제27권6호
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• pp.528-535
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• 2017

본 연구에서는 폴리페닐렌옥사이드 고분자에 브롬화반응을 통해서 할로겐 원소를 수월하게 도입하고, 도입한 할로겐 원소를 이미다졸륨으로 치환하여 이미다졸륨이 도입된폴리페닐렌옥사이드를 합성하였다. 다양한 특성평가를 통해서 합성이 이루어졌음을 확인하였고, 산소, 질소, 이산화탄소 기체투과 특성평가를 진행하여 합성한 고분자의 기체특성을 확인하였다. 이미다졸륨의 함량이 증가할수록 합성고분자의 이온교환용량이 증가하였으나, 기계적 강도는 감소하였다. 특히, 기체투과도는 미세하지만 감소하는 경향을 나타내었으며, 이산화탄소/질소 선택도의 경우 이미다졸륨 함량이 높아질수록 증가하는 경향을 확인할 수 있었다.

• Tribology and Lubricants
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• 제24권4호
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• pp.179-185
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• 2008

Microporous polymer lubricants(MPLs) are solid polymer materials containing micropores which are filled with liquid lubricants, and which are molded or formed to suit rolling bearings or other machine parts requiring lubrication. MPLs can be effectively applied to provide long-term, maintenance-free lubrication of a variety of machine elements without fully replacing of oils and greases. The application of rolling bearings packed fully with an MPL could reduce or eliminate the problems such as grease deterioration, leakage, under-lubrication caused by insertion of water or foreign matters under severe operation conditions. This paper discuss the application of MPLs for lubrication of rolling ball bearings. Two different MPLs were synthesized and the features of MPLs were tested. Characteristics of the bearings which are packed fully with synthesized MPLs were investigated using SEM, TG/DSC, extents of oil leakage, OIT, and life time test. After these preliminary tests twelve MPLs were synthesized and evaluated by measuring extents of oil leakage and OIT values. Then synthesis conditions for the optimum MPL were selected by SSRED(Six Sigma Robust Engineering Design) pro gram using extents of oil leakage and OIT values respectively. The optimum MPL by means of OIT value showed higher performance such as long life time and application at higher temperature of $140^{\circ}C$ than previous temperature of $100^{\circ}C$.

• Macromolecular Research
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• 제17권4호
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• pp.265-270
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• 2009

Noble thermosensitive nanoparticles, based on a PNIPAAm-co-AA core and a chitosan shell structure, were designed and synthesized for the controlled release of the loaded drug. PNIPAAm nanoparticles containing a carboxylic group on their surface were synthesized using emulsion polymerization. The carboxylic groups were conjugated with the amino group of a low molecular weight, water soluble chitosan. The particle size of the synthesized nanoparticles was decreased from 380 to 25 nm as the temperature of the dispersed medium was increased. Chitosan-conjugated nanoparticles with $2{\sim}5$ wt% MBA, a crosslinking monomer, induced a stable aqueous dispersion at a concentration of 1mg/1mL. The chitosan-conjugated nanoparticles showed thermo sensitive behaviors such as LCST and size shrinkage that were affected by the PNIPAAm core and induced some particle aggregation around LCST, which was not shown in the NIPAAm-co-AA nanoparticles. These chitosan-conjugated nanoparticles are also expected to be more biocompatible than the PNIPAAm core itself through the chitosan shell structures.

• 폴리머
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• 제32권3호
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• pp.239-245
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• 2008

Block copolymers of the general formula $[(-CO-R'-CO-HN-Ar-NH-CO-R'-CO)_xNH(CH_2)_3-(Me_2SiO)_y(CH_2)_3NH_2]_n$, [n=18.00 to 1175.0] where $R'=CH_2CH(CH_2GeCl_3)$;$CH_2CHGeCl_3CH_2$; and $Ar=-C_6H_4$;$-(o.CH_3C_6H_4)_2$;$-o.CH_3OC_6H_4)_2$;$-(o.CH_3C_6H_4)$ were prepared by a polycondensation reaction of polyamide containing a pendant trichlorogermyl group and terminal acid chloride $Cl(-CO-R'-CO-NH-Ar-NH-CO-R'-CO-)_xCl$ with aminopropyl-terminated polydimethylsiloxane $H_2N(CH_2)_3(Me_2SiO)_y-(CH_2)_3NH_2]$, (PDMS). These polymers were characterized by elemental analysis, $T_g$, FT-IR, $^1H$-NMR, solid state $^{13}C$-NMR, and molecular weight determination. The thermal stability of these copolymers was examined using thermal analysis techniques, such as TGA and DSC. Their molecular weights as determined by laser light scattering technique ranged $5.13{\times}10^5$ to $331{\times}10^5\;g/mol$. These polymers display their $T_g$ in the range of 337 to $393^{\circ}C$ with an average decomposition temperature at $582^{\circ}C$.

• 한국막학회:학술대회논문집
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• 한국막학회 1993년도 추계 총회 및 학술발표회
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• pp.58-58
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• 1993

Pervaporation has become important as a method to separate liquid mixtures, sepecially azeotropic and close boiling-point mixtures. Especially, water-alcohol separations have been carried out a lot because of the practical interests in the industries. However, outstanding membranes with high selectivity and high permeability have not been available in common use yet. In order to separate selectively out the water mixed with alcohols with an aim of the purification of the alcohols, a membrane has tO have excellent affinity to water. Among the hydrophilic polymers, polyacrylic acid and poly(vinyl alcohol) are used widely. In recent years, ionomers and polyion complexes, better hydrophitic materials, start to be used. The polyion complex membranes, consisting of polyacrylic acid (PAA) and polycation, showed excellent permeation rates and selectivities. It was known that among the polycations, ioneries, which have quaternary ammonium groups in the backbone chain, were more effective in giving membranes of higher permselectivities. On this base, syntheses and characterizations of the polycations, with different chemical structures from the published ones, for the polyion complex membrane formation were studied in this paper.

• Macromolecular Research
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• 제15권6호
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• pp.541-546
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• 2007

The combination of atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of well-defined block copolymers. Bromo terminated poly(methyl acrylate) (pMA-Br) was prepared by an ATRP initiator, ethyl-2-bromoisobutyrate (EBiB). Subsequently, the bromine chain end of pMA-Br was converted to an azide group by simple nucleophilic substitution reaction. ${\alpha}-Alkyn-{\omega}-bromo-functionalized$ polystyrene was also synthesized by ATRP using the alkyn-functionalized initiator, propargyl-2-bromoisobutyrate (PgBiB). In both cases, the conversion was limited to a low level to ensure a high degree of chain end functionality. Then the coupling reaction between the azide end group in $pMA-N_3$ and alkyn-functionalized PgBiB-pSt was performed by Cu(I)catalysis. This coupling reaction was monitored by gel permeation chromatography (GPC). The synthesized block copolymer was characterized by FT-IR, $^1H-NMR$ spectroscopy and $^1H-^1H$ COSY correlation spectroscopy.