• Title/Summary/Keyword: charge transfer complex

Search Result 67, Processing Time 0.082 seconds

Synthesis, Characterization, and Properties of Fully Aliphatic Polyimides and Their Derivatives for Microelectronics and Optoelectronics Applications

  • Mathews Anu Stella;Kim Il;Ha Chang-Sik
    • Macromolecular Research
    • /
    • v.15 no.2
    • /
    • pp.114-128
    • /
    • 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.

The Effect of Pressures on the Formation of Charge Transfer Complexes of Toluene with Iodine (I) (톨루엔과 요오드 사이의 전하이동착물에 대한 압력의 영향 (I))

  • Kwun Oh Cheun
    • Journal of the Korean Chemical Society
    • /
    • v.19 no.2
    • /
    • pp.73-84
    • /
    • 1975
  • The effect of pressures and temperatures on the stabilities of the toluene-iodine charge transfer complex have been investigated through ultraviolet spectrophotometric measurements in n-hexane. The stabilities of complexes were measured at $25~60{\circ}C$ under 1~1,200 bars. The equilibrium constant of the complex was increased with pressure and decreased with temperature raising. The absorption coefficient was increased with both pressure and temperature. Changes of volume, enthalpy, free energy and entropy for the formation of complexes were obtained from the equilibrium constants. The red-shift observed a higher pressure, the blue-shift at a higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions.

  • PDF

Cure Kinetics of Self-Extinguishing Epoxy Resin Systems with Charge Transfer Complex Type Latent Catalyst for Semiconductor Encapsulation (전하전이착체형 잠재성 촉매를 사용한 반도체 성형용 자소성 에폭시 수지 시스템의 경화 반응속도 연구)

  • Kim, Whan Gun
    • Journal of the Semiconductor & Display Technology
    • /
    • v.13 no.4
    • /
    • pp.27-32
    • /
    • 2014
  • The cure properties of self-extinguishing epoxy resin systems with different charge transfer type latent catalysts were investigated, which are composed of YX4000H as a biphenyl epoxy resin, MEH-7800SS as a hardener, and charge transfer type latent catalysts. We designed and used five kinds of charge transfer type latent catalyst and compared to epoxy resin systems with Triphenylphosphine-Benzoquinone(TPP-BQ) as reference system. The cure kinetics of these systems were analyzed by differential scanning calorimetry with an isothermal approach, the kinetic parameters of all systems were reported in generalized kinetic equations with diffusion effects. The epoxy resin systems with Triphenylphosphine-Quinhydrone(TPP-QH), Triphenylphosphine-Benzanthrone(TPP-BT) and Triphenylphosphine-Anthrone(TPP-AT) as a charge transfer type latent catalyst showed a cure conversion rate of equal or higher rate than those with TPP-BQ. These systems with TPP-QH and Triphenylphosphine-Tetracyanoethylene(TPP-TCE) showed a critical cure reaction conversion of equal or higher conversion than those with TPP-BQ. The increases of cure conversion rates could be explained by the decrease of the activation energy of these epoxy resin systems. It can be considered that the increases of critical cure reaction conversion would be dependent on the crystallinity of the biphenyl epoxy resin systems.

Deposition and Electrical Properties of (N-docosyl quinoliniurm)-TCNQ(1:2) Charge Transfer Complex Langmuir-Blodgett Films ((N-docosyl quinolinium)-TCNQ(1:2) 전하 이동 착물 Langmuir-Blodgett막의 누적 및 전기적 특성)

  • Jeong, Soon-Wook;Jeong, Hwae-Gul
    • Journal of the Korean Applied Science and Technology
    • /
    • v.17 no.1
    • /
    • pp.29-35
    • /
    • 2000
  • In this study, ultra-thin films of (N-docosyl quinolinium)-TCNQ(1:2) complex were prepared on the hydrophilic substrate by Langmuir-Blodgett(LB) technique. The characteristics of ${\pi}-A$ isotherms were studied to find optimum conditions of deposition by varying temperature of subphase, compression speed of barrier and amount of spreading solution. Using UV-vis spectra, capacitance and thickness, deposition of LB films was confirmed together with the thickness of the naturally oxidized aluminum film inside a device and dielectric constant of (N-docosyl quinolinium)-TCNQ(1:2) complex. The dielectric constant of LB film was about $4.59{\sim}5.58$. The electrical properties of (N-docosyl quinolinium)-TCNQ(1:2) complex were investigated at room temperature. The conductivity of this film measured by the direction of either vertical or horizontal axis was found to have a quite different value.

The Study on the Physicochemical Properties of Fluid under High Pressure (1). Effects of Pressure and Temperature on the Pentamethyl Benzene-Iodine Charge Transfer Complex in n-HexaneⅠ

  • Kim, Jeong-Rim;Kwun, Oh-Cheun
    • Bulletin of the Korean Chemical Society
    • /
    • v.6 no.2
    • /
    • pp.74-79
    • /
    • 1985
  • The stabilities of the charge transfer complexes of pentamethyl benzene with iodine in n-hexane have been investigated by UV-spectrophotometric measurements at 25, 40 and 60$^{\circ}C$ up to 1600 bars. The equilibrium constant of the complex formation was increased with pressure while being decreased with temperature raising. Changes of volume, enthalpy, free energy and entropy for the formation of the complexes were obtained from the equilibrium constants. The red-shift at higher pressure, the blue-shift at higher temperature, and the relation between pressure and oscillator strength have been discussed by means of thermodynamic functions. In comparison with the results in the previous studies, the absolute values of ${\Delta}$V at each temperature were increased with the number of methyl groups of polymethyl benzene. However, it can be seen that both ${\Delta}$H and ${\Delta}$S show extreme behaviors in durene near atmospheric pressure but they are negatively increased with the number of methyl groups near 1600 bar. This order of the thermodynamic parameters may be a measure of the relative basicities of polymethyl benzenes toward iodine under each pressure, and these phenomena are explained in terms of a positive inductive effect and a steric hindrance effect of the polymethyl benzene molecule.

Efficiency Factors of Singlet Oxygen Generation from Core-Modified Expanded Porphyric : Tetrathiarubyrin in Ethanol

  • Ha, Jeong Hyeon;Jeong, Guk Yeong;Kim, Min Seon;Lee, Yang Hun;Sin, Gu;Kim, Yong Rok
    • Bulletin of the Korean Chemical Society
    • /
    • v.22 no.1
    • /
    • pp.63-67
    • /
    • 2001
  • The photophysical properties and the singlet oxygen generation efficiency of tetrathiarubyrin have been investigated to elucidate the possibility of its use as a photodynamic therapy (PDT) photosensitizer by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were affected by various molecular aspects, such as extended ${\pi}conjugation$, structural distortion, and internal heavy atom. The steady-state electronic absorption spectrum was red-shifted due to the extended $\pi-conjugation$, and the spin orbital coupling was enhanced by the structural distortion and the internal heavy atom effect. As a result of the enhanced spin orbital coupling, the triplet quantum yield increased to 0.90 $\pm$ 0.10 and the triplet state lifetime was shortened to 7.0 $\pm$ 1.2 ${\mu}s$. Since the triplet state decays at a relatively faster rate, the efficiency of the oxygen quenching of the triplet state decreases. The singlet oxygen quantum yield was estimated to be 0.52 $\pm$ 0.02, which is somewhat lower than expected. On the other hand, the efficiency of singlet oxygen generation during the oxygen quenching of triplet state, $f{\Delta}^T$, is near unity. Such high efficiency of singlet oxygen generation can be explained by the following two possible factors: The hydrogen bonding of ethanol which impedes the deactivation pathway of the charge transfer complex with oxygen to the ground state, the less probability of the aggregation formation.

Charge Transfer Complexing Between Indole Derivatives and Methylviologen and Effects of Sodium Dodecyl Sulfate on It

  • Joon Woo Park;Sung-Jin Kim
    • Bulletin of the Korean Chemical Society
    • /
    • v.5 no.3
    • /
    • pp.121-126
    • /
    • 1984
  • The charge transfer complex formations between indole derivatives and methylviologen were investigated spectroscopically. In aqueous solutions near room temperature, the order of complex stability was tryptamine < tryptophan < indole < indole acetate, which is the reverse order of the magnitude of molar absorptivities. This was interpreted as involvement of contact charge transfer. The decrease of enthalpy of complex formation (-${\Delta}$H) was highest in tryptamine, and lowest in indole acetate. ${\Delta}$H and entropy of complex formation (${Delta}$S) varied nearly in a linear fashion with isokinetic temperature $242^{\circ}$K. These results were attributed to the hydration-dehydration properties of the side chains in indole derivatives. Except indole acetate, the complex formations were greatly enhanced by the addition of sodium dodecyl sulfate(SDS). However, the direct relationship between the enhanced complex formation and SDS micelle formation was not found. The enhanced charge transfer interaction inSDS solutions was attributed to the increased ${\Delta}$S by interaction between methylviologen and SDS in premicellar level. The order of complex stability in SDS solutions was indole acetate < tryptophan < trypamine < indole, which reflects the hydrophobicity of indole derivatives as well as electrostatic interaction between indole derivatives and methylviologen associated with SDS.

The Study on the Physicochemical Properties of Fluid under High Pressure (Ⅱ). The Effect of Pressure and Temperature on the Hexamethyl Benzene-Iodine Charge Transfer Complex in n-Hexane

  • Kwun Oh Cheun;Kim Jeong Rim
    • Bulletin of the Korean Chemical Society
    • /
    • v.6 no.4
    • /
    • pp.186-191
    • /
    • 1985
  • The effect of pressure and temperature on the stabilities of the charge transfer complexes of hexamethyl benzene with iodine in n-hexane has been investigated by UV-spectrophotometric measurements. In this experiment the absorption spectra of mixed solutions of hexamethyl benzene and iodine in n-hexane were measured at 25, 40 and $60^{\circ}C$ under 1,200, 600, 1200 and 1600 bar. The equilibrium constant of the complex formation was increased with pressure while being decreased with temperature raising. Changes of volume, enthalpy, free energy and entropy for the formation of the complexes were obtained from the equilibrium constants. The red shift at higher pressure, the blue shift at higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions. In comparison with the results in the previous studies, it can be seen that the pressure dependence of oscillator strength has a extremum behavior in durene as the variation of ${\Delta}H$ or ${\Delta}S$ with the number of methyl groups of polymethyl benzene near atmospheric pressure in the previous study. The shift or deformation of the potential in the ground state and in the excited state of the complexes formed between polymethyl benzene and iodine was considered from the correlation between the differences of the electron transfer energies and the differences of free energies of the complex formation for the pressure variation.

Charge-Transfer Complex Formation between Stilbenes and 7,7,8,8-Tetracyanoquinodimethane

  • Jin, Jung-Il;Kim, Joon-Seop;Kim, Jeong-Deuk
    • Bulletin of the Korean Chemical Society
    • /
    • v.9 no.3
    • /
    • pp.167-171
    • /
    • 1988
  • Formation of intermolecular charge-transfer complexes between 7,7,8,8-tetracyanoquinodimethane (TCNQ) and two different series of stilbene derivatives has been studied spectroscopically at $25^{\circ}$C in 1,2-dichloroethane. The compounds of Series I include stilbene and derivatives which have fused phenyl rings on one end of the central ethylene structure and a phenyl ring on the other end. The other Series, II, is comprised of stilbenes which have various para substituents on one of the two phenyl rings. The equilibrium constant, $K_c^{AD}$ and the molar extinction coefficient, ${\varepsilon}_{\lambda}^{AD}$, were determined using the Scott equation. The values of the charge-transfer transition frequency, ${\vu}_AD$ and $K_c{AD}$ correlated well respectively with the ionization potentials of the fused rings of Series Ⅰ or of the compounds of Series II and with the values of ${\sigma}_p$, the Hammett constants of the Series II substituents. trans-4-N,N-Dimethylaminostilbene and trans-4-nitrostilbene were found to be able to participate in electron transfer reaction with TCNQ forming the corresponding anion radical, TCNQ$^-$:

Copolymerization of Diethyl ${\alpha}$-Phenylvinyl Phosphate with Acrylonitrile and Maleic Anhydride (디에틸 ${\alpha}$-페닐비닐인산과 아크릴로니트릴 및 말레산무수물의 자유라디칼 혼성중합)

  • Jung-Il Jin;Hong-Ku Shim;Soo-Min Lee
    • Journal of the Korean Chemical Society
    • /
    • v.27 no.4
    • /
    • pp.287-293
    • /
    • 1983
  • Free radical-initiated copolymerizations of diethyl ${\alpha}$-phenylvinyl phospbate (DEPVP) with acrylonitrile (AN) and maleic anhydride (MAnh) were studied. The monomer reactivity ratios for AN/DEPVP pair, determined at $70^{\circ}C$ in bulk using benzoyl peroxide as an initiator, were;$ r_1(AN) = 0.77, r_2(DEPVP) = 0.002$. The values of the Alfrey-Price constants, Q and e, for DEPVP were calculated to be 0.012 and -1.35, respectively. Free radical-initiated copolymerization of MAnh/DEPVP pair in chloroform at $70^{\circ}C$ produced 1 : 1 alternating copolymers regardless monomer feed composition with the highest copolymerization rate at the molar ratio of MAnh : DEPVP = 7 : 3. The equilibrium constant of a charge-transfer complex between DEPVP and MAnh in deutrated chloroform, determinated at room temperature by transformed Benesi-Hildebrand NMR method, was 0.085 l/mol. The reduced viscosity of copolymers of AN/DEPVP pair decreased as the content of DEPVP units increased, while that of MAnh/DEPVP pair remained more or less constant.

  • PDF