• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.674-680
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• 2015

A solvent-soluble polyimide (PI) polymeric binder was synthesized by a two-step reaction for silicon (Si) anodes for lithium-ion batteries. Polyamic acid was first prepared through ring opening between two monomers, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA) and 4,4-oxydianiline (ODA), followed by condensation reaction. Using the synthesized PI polymeric binder (molecular weight = ~10,945), the coating slurry was then prepared and Si anode was fabricated. For the control system, Si anode based on polyvinylidene fluoride (PVDF, molecular weight = ~350,000) having the same constituent ratio was prepared. During precycling, PI polymeric binder revealed much improved discharge capacity ($2,167mAh\;g^{-1}$) compared to that of using PVDF polymeric binder ($1,740mAh\;g^{-1}$), while the Coulombic efficiency of two systems were similar. PI polymeric binder improved the cycle retention ability during cycles compared to that of using PVDF, which is attributed to an improved adhesion property inside Si anode diminishing the dimensional stress during Si volume changes. The adhesion property of each polymeric binder in Si anode was confirmed by surface and interfacial cutting analysis system (SAICAS) (Si anode based on PI polymeric binder = $0.217kN\;m^{-1}$ and Si anode based on PVDF polymeric binder = $0.185kN\;m^{-1}$).

• Proceedings of the Membrane Society of Korea Conference
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• 1996.04a
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• pp.42-43
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• 1996

고분자 분미막을 이용한 분리기술은 기존의 분리기술에 비하여 에너지의 절약과 높은 분리효율 등의 장점이 있어 거의 모든 산업에 이용되고 있다. 분리막의 용도가 다양화됨에 따라서 내열성, 내약품성, 내유기용매성을 갖는 막소재의 개발이 필요하게 되었다. polyimide(PI)게의 고분자는 물리, 화학적 성능이 우수하고 내열성과 내유기용매성 등이 우수한 열가소성수지로서 film, sheet, tubular형으로 만들 수 있어 한외여과막이나 역삼투막, 기체분리막 등에 이용되고 있다. 그러나 투과속도를 높디고, fouling을 줄이기 위해서는 화학적 개질을 통해 친수성을 높이는 방법이 필요하다. 본 실험에서는 내열성과 내유기용매성이 우수한 polyetherimide계 고분자를 chlorosulfonic acid(CSA)를 이용하여 술폰화시킴으로써, 극성기의 도입에 의해 친수성이 향상된 sulfonated polyetherimide(SPEI)를 합성하였다.

• Macromolecular Research
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• v.11 no.6
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• pp.458-466
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• 2003

Several copolyimides have been synthesized with different combinations of comonomers in order to study the relationship between conductivity and water insolubility. m-Phenylenediamine (m-PDA), an angled comonomer, was introduced into the polymer backbone to increase water absorption, and resulted in higher proton conductivity. 2,2-bis(trifluoromethyl)benzidine (TFMB) was used as the comonomer to promote water insolubility. There is a good correlation between the water uptake and conductivity of the polyimides. The copolyimides that had high water uptake also generated high proton conductivity. Those polyimides had good mechanical properties. The copolyimides that have 27 mol% of TFMB and 9 mol% of m-PDA have reasonable conductivities and are insoluble in water at 90$^{\circ}C$, even though they have lower conductivities than those of the homopolymer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.551-552
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• 2006

This study was attended to demonstrate synthesis of silver nanoparticles stabilized with polymer and their applicability to printed electronics. Silver nanoparticles were synthesized by reduction of silver nitrate in aqueous solution in the presence of polyvinyl pyrrolidone (PVP) as a stabilizer. The ink used here is composed of 50 wt% Ag NP, 15 wt% humectant and then were printed on polyimide film. Particle deposit morphologies were controlled by varying the ink compositions. Printed silver patterns and dots were cured on a convection oven in air at $300^{\circ}C$ for 60 min. The printed patterns show good shape definition and the resistivity of the printed films is about $5{\mu}{\Omega}{\cdot}cm$.

• Applied Chemistry for Engineering
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• v.2 no.3
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• pp.253-261
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• 1991

Polyamic acids, precursor polymers of polyimides have been obtained by the solution polycondensation of benzophenone tetracarboxylic dianhydride (BTDA) with 4, 4'-diamino diphenyl methane (MDA) and/or 3, 3'-dimethyl benzidine (OTB). The reaction was carried in two solvent systems such as m-cresol and m-cresol/xylene mixture. The results of TGA analysis showed that the polyimide films had good thermal stability with the initial decomposition temperature ranging from $540^{\circ}$ to $590^{\circ}$. According to DSC analysis of polymers, the glass transition temperature was over $340^{\circ}$. Polyimide film samples, showed good mechanical and electrical properties, had over $16Kg/mm^2$ of tensile strength and about 200 KV/mm of dielectric breakdown voltage. The properties of the copolymer from MAD/OTB were better than those of the homopolymer from MDA. And the polymer synthesized in m-cresol had lower properties than that obtained in m-cresol/xylene.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.229-236
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• 1998

In this paper, thin films of Polyimide (PI) were fabricated by vapor deposition polymerization method (VDPM) of dry processes. The film's properties with curing temperature and electrical properties were studies. The synthesis of hexafluoroisopropyliden-2,2-bis[phthalic anhydride](6FDA) and 4, 4'-diamino diphenyl ether (DDE) was carried out by vapor deposition polymerization(VDP) with the same deposition rate. The evaporation temperature of 6FDA and DDE were $214^{\circ}C$ and $137^{\circ}C$, respectively, so as to preserve balance of stoichiometry. The polymic acid (PAA) made by VDPM were changed to PI by thermal curing. The uniformity and density of PI thin films were increased according to increasing curing temperature. The relative permittivity and dissipation loss factor were 3.7 and 0.008 at the frequency of 100Hz~200KHz, respectively, for the fabricated in the curing temperature of $300^{\circ}C$. Also, the resistivity was about 1.05$\times$$ 10^{15}$$\Omega$cm at $30^{\circ}C$.

• Polymer(Korea)
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• v.28 no.6
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• pp.494-501
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• 2004

A new alkali developable photosensitive poly(amic acid) (PAA-0) with transmittance at 400 nm was synthesized from cyclobutane-1,2,3,4-tetracarboxylic dianhydride, 2-(methacryloyloxy)ethyl-3,5-diamino-benzoate and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyl disiloxane in N-methyl-2-pyrrolidinone. Photosensitivity of the PAA-0 was investigated at 365-400 nm in the presence of a photoinitiator using a high pressure mercury lamp. The photo-cured poly(amic acid) was insoluble toward aqueous 2.38 wt% tetramethylammonium hydroxide solution. Negative pattern of the PAA-0 with 25 ${\mu}{\textrm}{m}$ resolution was obtained by developing with 2.38 wt% tetramethylammonium hydroxide solution after exposure of 600 mJ/$\textrm{cm}^2$ in the presence of 2,2-dimethoxy-2-phenyl-acetophenone as a photoinitiator. The patterned poly(amic acid) was converted to polyimide by thermal curing at 25$0^{\circ}C$ for 50 min, which showed chemical resistance against photoresist stripper as well as good transmittance at 400 nm.

• Polymer(Korea)
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• v.26 no.6
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• pp.701-709
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• 2002

To synthesize a new positive photosensitive polyimide precursor, parts of carboxylic acid groups in poly (amic acid) were esterified with 4,5-dimethoxy-2-nitrobenzyl bromide in the presence of K$_2$CO$_3$/HMPA followed by the chemical imidization of residual carboxylic acid units. The chemical structure of resulting polymer was characterized by $^1$H-NMR, UV/vis and FT-IR spectroscopic methods, and its thermal properties were examined by DSC and TGA. Upon UV irradiation, 4,5-dimethoxy-2-nitrobenzyl moiety underwent the photodegradation. As a result, the polymer became soluble in alkaline developer due to the formation of carboxylic acid moiety, which was used to make a micron-sized positive pattern. Sensitivity curves were obtained from the gel fraction experiments with respect to the various 4,5-dimethoxy-2-nitrobenzyl ester contents. From those curves, the sensitivity was ranged iron 4000 to 6000 mJ/㎠, and the contrast was measured to be from 3.1 to 4.9.

• Membrane Journal
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• v.25 no.4
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• pp.343-351
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• 2015

In this study, we synthesis polyimide with high gas selectivity using 2,2-bis(3,4-carboxylphenyl) hexafluoropropane, 2,4,6-Trimethyl-1,3-phenylenediamine (DAM) and 4,4-Methylenedianiline (p-MDA), and then the asymmetric membrane was fabricated by non-solvent phase separation method. To confirm the property change of the membrane using different solvent, we measured and compared the viscosity of the polymer solution, cloud point and non-solvent phase separation coefficient. The morphology and gas separation property of membrane prepared by phase separation method was confirmed using Field Emission Scanning Electron Microsope and the single gas permeation measurement apparatus. The single gas ($CH_4$, $N_2$, $O_2$, $CO_2$) permeation property and selectivity value of the membrane prepared with NMP was higher than the membrane prepared with DMAc. We confirmed that the gas selectivity of the membrane increased and the permeation property decreased with increasing of the solvent evaporation time.

• Polymer(Korea)
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• v.33 no.3
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• pp.207-212
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• 2009

The precursor polyimide of the photoreactive polyimides(PI-SP6 and PI-SP12) was prepared from a derivative of 2, 2, 2-trifluoroethane dianhydride and 3,3'-dihydroxy-4,4'-diaminobiphenyl. PI-SP6 and PI-SP12 were then prepared by the polymer reactions of the precursor polyimide with photoreactive 2-styrylpyridine alkylene (hexylene and dodecylene) derivatives, respectively. The photoreactive polymers were soluble in organic solvents. The polymers showed the initial decomposition temperatures around $350^{\circ}C$. The glass transition temperatures of PI-SP6 and PI-SP12 were found to be $130^{\circ}C$ and $85^{\circ}C$, respectively. This result means that the latter polymer is more flexible than the former polymer. Their transmittance in the film state was 90% at $250^{\circ}C$, which indicates that the photosensitive polyimides with thermal stability have high optical transparency even at the high temperature. The respective dichroic ratios of PI-SP6 and PI-SP12 were found to be 0.01 and 0.03 at an exposure energy of $1.5\;J/cm^2$. This result suggests that the latter polymer with larger flexibility compared to the former polymer is more effective for the photoalignment.