• Macromolecular Research
• /
• v.17 no.9
• /
• pp.646-650
• /
• 2009

We report the fabrication of pentacene organic field-effect transistors (OFETs) using a fluorinated styrene-alt-maleic anhydride copolymer gate dielectric, which was prepared from styrene derivatives with a fluorinated side chain [$-CH_2-O-(CH_2)_2-(CF_2)_5CF_3$] and maleic anhydride through a solution polymerization technique. The fluorinated side chain was used to impart hydrophobicity to the surface of the gate dielectric and maleic anhydride was employed to improve its wetting properties. A field-effect mobility of 0.12 cm$^2$/Vs was obtained from the as-prepared top-contact pentacene FETs. Since various functional groups can be introduced into the copolymer due to the nature of maleic anhydride, its physical properties can be manipulated easily. Using this type of copolymer, the performance of organic FETs can be enhanced through optimization of the interfacial properties between the gate dielectric and organic semiconductor.

• Polymer(Korea)
• /
• v.38 no.3
• /
• pp.265-271
• /
• 2014

In order to investigate the characteristics of the gradient fluorinated polyacrylate and polyurethane latex blend films, the fluorinated polyacrylate emulsion and the polyurethane emulsion were synthesized, and then the both emulsions were blended at a series of ratios. The effects of content of the fluorinated polyacrylate on the gradient structure and surface property of the blended films were assessed by AFM, XPS, SEM-EDX and surface free energy measurements. It appeared that, while the content of the fluorinated polyacrylate latex was up to 30%, the fluorinated polyacrylate particles were selectively gathered on the film-air (F-A) and film-glass (F-G) interfaces at room temperature. When the content of the fluorinated polyacrylate was under 30%, the gradient structure of fluorinated component was not evident. The further increasing of fluorinated polyacrylate in the mixed system facilitated the formation and enlargement of gradient structure, but the adhesion of film decreased a little.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.516-519
• /
• 2003

We modified the molecular structure of urethane acrylate oligomer by varying raw materials. Also fluorination of the host polymer matrices has been found to influence the morphological and the electrooptical properties of the resulting HPDLC grating. The incorporation of fluorinated monomers in HPDLC formulation enhance the LC phase separation and improved elctro-optical properties.

• Carbon letters
• /
• v.26
• /
• pp.25-30
• /
• 2018

The dielectric medium used in electrophoretic displays (EPDs) is required to be an environmentally friendly solvent with high density, low viscosity, and a large electric constant. Hydrofluoroether, a highly fluorinated solvent with eco-friendly characteristics, is regarded as a viable alternative medium for EPDs, owing to the similarity of its physical properties to those of the conventional EPD medium. Surface modification of particles is required, however, in order for it to disperse in the charged solvent. Also, positive/negative charges should be present on the particle surface to enable electrophoretic behavior. In this study, carbon black particles wrapped with positively charged nitrogen (N-CBs) were fabricated by a simple hydrothermal process using a poly(diallyldimethylammonium chloride) solution as a black coloring agent for the EPD. The dispersion behavior of N-CBs was investigated in various solvents.

• Journal of Information Display
• /
• v.10 no.4
• /
• pp.180-183
• /
• 2009

A stamping-assisted rubbing technique for generating bidirectional alignment in the fabrication of wide-viewing twistednematic (TN) liquid crystal displays (LCDs) was developed. A patterned layer of a fluorinated acrylate polymer was transferred onto the first rubbed alignment layer prepared on a substrate by stamping. The fluorinated acrylate polymer provides a protective layer that covers the first alignment layer during the second rubbing process to facilitate the bidirectional alignment of the LC molecules. The LC cell in the twisted geometry with two bidirectional-alignment layers showed stable electro-optic properties and wide-viewing characteristics. The stamping-assisted rubbing technique serves as a mask-free alignment method of producing multidomains for wide-viewing LCDs.

• Journal of Information Display
• /
• v.7 no.1
• /
• pp.7-11
• /
• 2006

In this paper, we report the fabrication of high quality polymer walls by using a monomer containing fluorine (F-monomer). Polymer walls with no phase retardation were fabricated by using photo-polymerization induced anisotropic phase separation of the mixture composed of liquid crystal (LC) and F-monomer. Thanks to the immiscibility of fluoride, we could form high quality polymer walls with no light leakage. We measured electro-optic characteristics of a twisted-nematic (TN) LC cell whose polymer walls were fabricated by using the F-monomer, and the measurements were compared with that fabricated by using the monomer without fluorine.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.409-414
• /
• 2007

Wettability of solid surfaces with liquids is governed by the chemical properties and the microstructure of the surfaces. We report on the preparation of liquid-repellent surfaces using surface-attached monolayers of perfluorinated polymer molecules on porous silica substrates. A covalent attachment of the polymer molecules to the substrate is achieved by generation of the polymer chains through starting a surface-initiated radical-chain polymerization of a fluorinated monomer. To this, self-assembled monolayers of azo initiators are attached to silica substrates, which are used to kick off the polymerization reaction in situ. The growth of the fluorinated polymer films and the characterization of the obtained surfaces by surface plasmon spectroscopy, XPS, and contact angle measurements is described. It is shown that perfluorinated polymer films can be grown with controlled thicknesses on flat and even on porous silica surfaces, essentially without changing the surface roughness. The combination of the low surface energy coating and the surface porosity allows generation of materials which are both water and oil repellent.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2000.01a
• /
• pp.213-214
• /
• 2000

New light-emitting polyimides were synthesized from the conventional polycondensation of 5,5'-bis(4-aminophenyl)-2,2'bifuryl (PFDA) with fluorinated and non-fluorinated aromatic dianhydrides, providing a good quality of thin films: 6F-PFDA PI and ODPA-PFDA PI. Their UV-visible absorbance and photoluminescent characteristics were investigated. The polymers emit blue and blue-greenish light in a quantum yield of 7.3-14.9%, depending on the polymer backbone.

• Korean Membrane Journal
• /
• v.9 no.1
• /
• pp.43-51
• /
• 2007

This paper describes the preparation and characterization of two kinds of fluorinated polybenzimidazole (PBI)s which can be potentially used for phosphoric acid-doped, high-temperature polymer electrolyte membrane fuel cells. Two kinds of perfluorocyclobutane (PFCB)-containing monomers were prepared via following synthetic steps; after fluoroalkylation of methyl 3-(hydroxy) benzoate and methyl 4-(hydroxy) benzoate with 1,2-dibromotetrafluoroethane and subsequent Zn-mediated dehalogenation, these compounds were cyclodimerized at $200^{\circ}C$ affording the ester-terminated monomers containing PFCB ether groups. The synthesized intermediates and monomers were characterized using FT-IR, $^1H-NMR,\;^{19}F-NMR$, and mass spectroscopy. The fluorinated PBIs were then successfully prepared through the solution polycondensation of the monomers and 3,3'-diaminobenzidine in polyphosphoric acid. Compared with traditional PBI, the glass transition temperatures of the fluorinated PBIs were obtained at $262^{\circ}C\;and\;269^{\circ}C$ which are lower than that of PBI and their initial degradation temperatures were still high over $400^{\circ}C$ under nitrogen. The fluorinated PBIs showed higher d-spacing values and improved solubility in several organic solvents as well as phosphoric acid, which confirmed they could be good candidates for the high temperature fuel cell membranes.

• Elastomers and Composites
• /
• v.50 no.3
• /
• pp.175-183
• /
• 2015

A series of fluorinated aromatic poly(hydroxyamide)s (PHAs) were synthesized by direct polycondensation of diacides containing 2,6-dimethylphenoxy group and quinoxaline ring in the main chain with 2,2-bis-(3-amino-4-hydroxyphenyl) hexafluoropropane. The PHAs had relatively low inherent viscosities in the range of 0.35~0.43 dL/g at $35^{\circ}C$ in DMAc solution. All PHAs exhibited excellent solubility in aprotic solvents such as NMP, DMAc, DMF and DMSO as well as in common organic solvents such as pyridine, THF, and m-cresol at room temperature. However, the poly(benzoxazole)s (PBOs) were quite insoluble in all organic solvents except partially soluble in concentrated sulfuric acid. The PBOs showed glass transition temperatures between 233 and $284^{\circ}C$ by DSC and maximum weight loss temperatures in the range of $536-546^{\circ}C$ by TGA.