• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.49-57
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• 2004

The modified polyionene polyelectrolyte inks were newly prepared and applied to the humidity-sensitive membrane of humidity sensor. The films were fabricated on the alumina substrate with comb-type gold electrode using a ink-jet printing technique. The copolymers of methyl methacrylate, acrylic acid, 2-hydroxyethyl methacrylate and [(2-methacryloyloxy)ethyl]trimethylammonium chloride were also prepared for the humidity-sensing material. which was fabricated by dip-coating method. Electrical measurements under various relative humidity were performed. The humidity-sensitive characteristics of sensors obtained by ink-jet printing technique were compared with that of dip-coating method. Humidity sensors showed a decrease in resistance as an increase of relative humidity and their resistance characteristics are in a close agreement each other.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3061-3063
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• 2016

Exploiting the immune system to abolish cancer growth via vaccination is a promising strategy but that is limited by many clinical issues. For DNA vaccines, viral vectors as a delivery system mediate a strong immune response due to their protein structure, which could afflect the cellular uptake of the genetic vector or even induce cytotoxic immune responses against transfected cells. Recently, synthetic DNA delivery systems have been developed and recommended as much easier and simple approaches for DNA delivery compared with viral vectors. These are based on the attraction of the positively charged cationic transfection reagents to negatively charged DNA molecules, which augments the cellular DNA uptake. In fact, there are three major cellular barriers which hinder successful DNA delivery systems: low uptake across the plasma membrane; inadequate release of DNA molecules with limited stability; and lack of nuclear targeting. Recently, a polysaccharide polymer produced by microalgae has been synthesized in a form of polymeric fiber material poly-N-acetyl glucosamine (p-GlcNAc). Due its unique properties, the F2 gel matrix was suggested as an effective delivery system for immune and gene vaccinations.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.635-643
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• 2016

Graphene has shown exceptional properties for high performance devices due to its high carrier mobility. Of particular interest is the potential use of graphene nanoribbons as field-effect transistors. Herein, we introduce a facile approach to the fabrication of graphene nanoribbon (GNR) arrays with ~200 nm width using nanoimprint lithography (NIL), which is a simple and robust method for patterning with high fidelity over a large area. To realize a 2D material-based device, we integrated the graphene nanoribbon arrays in field effect transistors (GNR-FETs) using conventional lithography and metallization on highly-doped $Si/SiO_2$ substrate. Consequently, we observed an enhancement of the performance of the GNR-transistors compared to that of the micro-ribbon graphene transistors. Besides this, using a transfer printing process on a flexible polymeric substrate, we demonstrated graphene-silicon junction structures that use CVD grown graphene as flexible electrodes for Si based transistors.

• Analytical Science and Technology
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• v.10 no.6
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• pp.453-458
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• 1997

Many polymeric poly(vinyl chloride) membrane electrodes have been developed for the determination of basic drugs. But relatively little has been roported concerning the behavior of ligand free PVC memebranes. In connection with the evaluation of various ionophores, we bave evaluated a near-Nernstian response and selectivity of these ligand-free PVC electrodes towards basic drugs such as alverine, chlorpromazine and promazine. The electrode membranes were constructed with only several plasticizer and poly (vinyl chloride) matrix. The plasticizer studied were dioctyl phenylphosphonate, 2-nitrophenyl octyl ether, isododecyl phenylphosphate and dioctyl maleate.

• Bulletin of the Korean Chemical Society
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• v.15 no.8
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• pp.650-654
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• 1994

Stable polyion-complexed polymeric monolayers were prepared by spreading perfluoroalkyl monomaleate copolymers, $C_2F_8MA-VE_2$ and $C_2F_8MA-VE_3$, on a aqueous poly(allylamine) subphase. The monolayer properties have been studied by the surface pressure-area (${\pi}$-A) isotherms. The $C_2F_8MA-VE_3$ containing longer oligoethyleneglycol pendant showed more expanded monolayer phase than the $C_2F_8MA-VE_2$. The polyion-complexed monolayers were transferable on various substrates, and the resulting Langmuir-Blodgett (LB) films were characterized by FT-IR spectroscopy and scanning electron microscopy (SEM). Two-dimensional crosslinking to form a polymer network was achieved by amide formation through heat treatment under vacuum with concurrent removal of perfluoroalkyl tails. SEM observation of this film on a porous membrane filter showed that the four layer film was sufficiently stable to cover the filter pore size of 0.1 ${\mu}$m. The $C_2F_8MA-VE_3$ revealed better covering capability than the $C_2F_8MA-VE_2$. Immersion of this film in water or in benzene did not cause any change in its appearance and in Fl-IR spectra.

• Membrane Journal
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• v.20 no.3
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• pp.249-258
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• 2010

In this study, we tried to observe the permeation on the single $O_2$, $CF_4$ and $SF_6$ gas using a PSF (polysulfone), PC (tetra-bromo polycarbonate) and PI (polyimide) hollow fiber membranes. We also observed the permselectivity on the $O_2/SF_6$ and $CF_4/SF_6$. According to the results of single gases permeation for different pressures, PSF membrane has the highest $O_2$ permeation of 37.5 GPU and PC membrane has the highest $SF_6$ permeation of 2.7 GPU and the highest $CF_4$ permeation of 2.5 GPU at 1.1 MPa. According to the results of single gases permeation for different temperatures, PSF membrane has the highest permeation of $O_2$ at $45^{\circ}C$ and PC membrane has the highest permeation of $SF_6$ and $CF_4$ at $25^{\circ}C$. From the result of $O_2/SF_6$ and $CF_4/SF_6$ permselectivity for different pressures and temperature, the highest permeation and the lowest permselectivity were observed in the PSF and PC membrane. On the contrary, the lowest permeation and the highest permselectivity was observed in the PI membrane.

• Membrane Journal
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• v.21 no.3
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• pp.299-305
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• 2011

This study deals with the preparation of polymeric electrolyte membranes having high durability for the application of fuel cells. The membranes under investigation were prepared the impregnation to porous polyethylene membranes with poly(vinyl alcohol)(PVA), poly(styrene sulfonic acid-co-maleic acid), and (PSSA-MA)3-(trihydroxysilyl)-1-propanesulfonic acid (THS-PSA). To characterize the resulting membranes, the water contents, the contact angles, FT-IR, the proton conductivity and the the modulus were measured. The proton conductivity of 30% content of THS-PSA at $55^{\circ}C$ gave excellent $1.27{\times}10^{-1}S/cm$ and the mechanical strength was improved 7 times higher up to the THS-PSA content 15%, as a result, the durability was elevated extensively.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.319-328
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• 1994

Aluminium and titanium precursors containing $\beta$-diketonate ligands were used for the synthesis of polymeric sols of alumina and titania by sol-gel methods. To prepare polymeric sols by solgel processing, we synthesized modified precursors having chelating organic ligands. With these precursors it was found to be possible to control both hydrolysis and polycondensation reaction rates which resulted in ultrafine particles few nms of average size. The optimum molar ratio of acid to alkoxide for alumina sol was 0.3-0.4 and that of water to alkoxide &as 1. On the other hand, the corresponding ratios for titania sol were found be 0.25-0.20 and 1 respectively. Dynamic light scattering measurements indicated that the average particle size in both sols was in the order of few nms. SEM photographs were taken to observe crack-free and smooth surfaces of coated membranes after sintering at $450^{\circ}C$. Alumina coated membrane on a slide glass had about 4-4.5$\mu \textrm{m}$, thickness and titania coated one had 2-2.5$\mu \textrm{m}$, thickness. And according to TEM photographs, the grain size of titania was smaller than 30nm and that of alumina was in the range of few $\AA$s to 2nms. An X-ray diffraction study revealed that alumina was $\gamma$ phase and titania was anatase crystal.

• Korean Journal of Materials Research
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• v.3 no.6
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• pp.598-605
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• 1993

Methacryloxyethyl dimethyl alkyl($C_{1}\sim C_{12}$, benzyl and 2, 2-diethoxy ethyl) ammonium bromide monomers were prepared to investigate the relative humidity characteristics for polymer electrolytes with different chemical structures. They were coated on the alumna substrate printed comblike gold electrode by photopolymerization after micro-syringe injection. As the thickness of rhe humid membrane increased, the impendance decreased, whereas the impedance ~ncreased as the carbon cham of alkyl substituent in the monomer increased. The impendance of the polymeric electrolytes with $C_6\sim C_8$ substituents were varied from 19M$\Omega$ to 5K$\Omega$ for the range of 30-90% Mi. The temperature depedence coefficient in the range of 15-$35^{\circ}C$ was found to be -0.45% $RH/^{\circ}C$and the hysteresis falled within the range of $\pm$2% RH. The response time was 35 second for varying humldity from 33% to 85% RH.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.4
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• pp.205-212
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• 2001

One of the important characteristics of biological systems os their ability to change im-portant properties in response to small environmental signals. The molecular mechanisms that biological molecules utilize to sense and respond provide interesting models for the development of "smart" polymeric biomaterials with biomimetic properties. An important example of this is the protein coat of viruses, which contains peptide units that facilitate the trafficking of the virus into the cell via endocytosis, then out of the endosome into the cytoplasm, and from there into the nucleus, We have designed a family of synthetic polymers whose compositions have been de-signed to mimic specific peptides on viral coats that facilitate endosomal escape. Our biomimetic polymers are responsive to the lowered pH whinin endosomes, leading to distruption of the en-dosomal membrane and release of important biomolecular druges such as DNA, RNA, peptides and proteins to the cytoplasm before they are trafficked to lysosomes and degraded by lysosomal en-zymes. In this article, we review our work on the design, synthesis and action of such smart, pH-sensitive polymers.