• Macromolecular Research
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• v.17 no.6
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• pp.451-454
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• 2009

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.999-1005
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• 2004

A new stamp fabrication technique for the soft lithography has been developed in the range of several microns by means of a nano-replication printing (nRP) process. In the nRP process, a figure or a pattern can be replicated directly from a two-tone bitmap figure with nano-scale details. A photopolymerizable resin was polymerized by the two-photon absorption which was induced by a femtosecond laser. After the polymerization of master patterns, a gold metal layer (about 30 ㎚ thickness) was deposited on the fabricated master patterns for the purpose of preventing a join between the patterns and the PDMS, then the master patterns were transferred in order to fabricate a stamp by using the PDMS (poly-dimethylsiloxane). In the transferring process, a few of gold particles, which were isolated from the master patterns, remained on the PDMS stamp. A gold selective etchant, the potassium iodine (KI) was employed to remove the needless gold particles without any damage to the PDMS stamp. Through this work, the effectiveness of the nRP process with the PDMS molding was evaluated to make the PDMS stamp with the resolution of around 200 ㎚.

• Polymer(Korea)
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• v.24 no.1
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• pp.8-15
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• 2000

Phenolic/furfural(P/F) gel microspheres were successfully produced by new supercritical $CO_2$-based process. $CO_2$-soluble poly(dimethylsiloxane) (PDMS) was used as the stabilizer in this system. Spherical morphology of the gel microspheres was confirmed by scanning electron microscopy. Particle size and particle size distribution of P/F gel microspheres can be modified by variety of the solids content and the stabilizer content. The resultant P/F gel microspheres have average particle size in the range of 1-6 ${\mu}{\textrm}{m}$. The structure of P/F gel microspheres was revealed by thermogravimetric analysis and IR analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.5
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• pp.671-675
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• 2014

This paper presents a fabrication of hydrophilic Poly(dimethylsiloxane) (PDMS) with periodic wrinkling surface. The proposed periodic wrinkling surface was fabricated using the sequential processes of typical curing process of PDMS, cutting process, platinum deposition process, and wrinkling transfer process. The surface morphology of the fabricated wrinkling surface was observed by using optical and dynamic atomic force microscopy and discussed. The measured period and amplitude of wrinkling was about $2.2{\mu}m$ and $0.31{\mu}m$, respectively. And, the contact angles of water droplets on the wrinkled surface were measured in order to understand effect of the wrinkling surface on surface modification of hydrophobic PDMS. Our new finding was that the proposed wrinkling surface was hydrophilic and the measured contact angle was about $62^{\circ}$. Moreover, it was found out from the simple cell culture test that the fabricated wrinkling surface was more effective for cell spreading and adhesion than the case of native PDMS substrate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.377-377
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• 2007

A simplified integration process including packaging is presented, which enables the realization of the portable fluorescence detection system. A fluorescence detection microchip system consisting of an integrated PIN photodiode, an organic light emitting diode (OLED) as the light source, an interference filter, and a microchannel was developed. The on-chip fluorescence detector fabricated by poly(dimethylsiloxane) (PDMS)-based packaging had thin-film structure. A silicon-based integrated PIN photo diode combined with an optical filter removed the background noise, which was produced by an excitation source, on the same substrate. The active area of the finger-type PIN photo diode was extended to obtain a higher detection sensitivity of fluorescence. The sensitivity and the limit of detection (LOD S/N = 3) of the system were $0.198\;nA/{\mu}M$ and $10\;{\mu}M$, respectively.

• Membrane Journal
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• v.13 no.4
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• pp.291-299
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• 2003

Polymer membranes such as poly(1-trimethylsilyl-1-propyne)-polyetherimide (PTMSP-PEI) and poly(dimethylsiloxane)- polyetherimide (PDMS-PEI) composite membrane were prepared by solution casting method. To investigate the characteristics of these membranes, the analytical methods such as FT-IR, $^1H-NMR,$ DSC, TGA, GPC, and SEM have been utilized. The number-average (equation omitted) and weight-average (equation omitted) molecular weight of PTMSP were 477,920 and 673,329 respectively. The glass transition temperature ($T_g$) of PTMSP was $224^{\circ}C.$ The separation of the gas mixture ($H_2/N_2$) through the composite membranes were studied as a function of pressure. The separation factor (${\alpha}, {\beta},$ quation omitted) of the composite membranes used in this work increased as the pressure of permeation cell increased. The real separation factor (${\alpha}$), head separation factor (${\beta}$), and tail separation factor (equation omitted) of PTMSP-PEI composite membrane were 2.28, 1.17, and 1.96 respectively at ${\Delta}P$ 30psi and $25^{\circ}C.$ (${\alpha}, {\beta}$ and equation omitted of PDMS-PEI composite membrane were 3.70, 1.53, and 2.42 respectively at ${\Delta}P$ 30psi and $25^{\circ}C$.

• Polymer(Korea)
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• v.35 no.6
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• pp.615-618
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• 2011

Carbon nanotubes (CNTs) draw attention as promising materials due to their excellent electrical and mechanical properties. However, the intrinsic strong interaction between CNTs presents a challenge to their use in various applications. Here, we present a facile method to disperse single-walled carbon nanotubes (SWCNTs) in a polar solution using a graft copolymer, poly(vinyl chloride)-graft-poly(oxyethylene methacrylate), PVC-g-POEM. The graft copolymer was synthesized via atom transfer radical polymerization (ATRP), as confirmed by gel permeation chromatography (GPC) and $^1H$ NMR spectroscopy. The SWCNTs were uniformly dispersed in a polar solvent such as dimethylsiloxane (DMSO) using PVC-g-POEM as a dispersant, due to interaction between CNT and the graft copolymer, as revealed by transmission electron microscopy (TEM) analysis. Upon removal of the solvent, free standing nanocomposite films with good homogeneity were obtained.

• Membrane Journal
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• v.29 no.1
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• pp.51-60
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• 2019

In order to improve gas separation properties of polymeric membranes which have been widely applied in the industry field, aluminosilicate hollow nanoparticles named as allophanes were synthesized by sol-gel method and formulated in Poly(dimethylsiloxane) (PDMS) matrix to investigate the gas separation properties of PDMS membrane. Transmission electron microscope (TEM), Energy dispersive X-ray analysis (EDX), X-ray diffractometer (XRD), Surface area and pore size analyzer (BET) and Fourier transform infrared spectrophotometer (FTIR) were carried out to characterize the synthetic allophanes. Then the PDMS mixed matrix membranes were prepared by adding different volume fraction of allophanes. To examine the effect of allophanes addition in PDMS matrix using unmodified allophane and modified ones, the gas permeation experiments were performed using oxygen, nitrogen, methane and carbon dioxide. As the volume fraction of modified allophane increased up to 4.05 Vol% the permeability of four test gases through PDMS mixed matrix membranes increased. Also, the selectivity of $O_2/N_2$ and $CO_2/CH_4$ increased with the contents of the modified allophane. Further improvement of gas separation properties of PDMS mixed matrix membranes containing higher volume percent of allophanes can be expected as long as well dispersion of allophanes in PDMS matrix can be achieved for better PDMS membranes.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.390-390
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• 2014

Soft-lithography 기술 중의 하나인 Micro-Contact Printing (${\mu}$-CP) 기술은 패턴이 형성된 mold 위에 고분자 물질을 코팅하고 기판과 접촉시켜, 패턴 된 부분만 기판으로 전사시켜 패턴을 형성하는 방법이다. ${\mu}$-CP 기술은 Imprint 방식과 비교하여 잔여물을 제거하기 위한 ashing 공정이 필요 없으며, 상대적으로 패턴이 전사되기 위한 공정 온도와 압력이 낮은 장점이 있다. 한편, 기존의 Photolithography 기술로 유기기판에 패턴을 형성하는 것은 제한이 있으며, 자외선에 의해 유기기판의 특성이 변화될 수 있다. 또한 패턴 형성 후 고분자 패턴을 제거하는 용매가 기판이 손상 받게 된다. 본 실험에서는 poly (1H,1H,2H,2H-perfluorodecyl methacrylate) polymer (PFDMA) films을 패턴 된 poly (dimethylsiloxane) (PDMS) mold 위에 코팅하고 ${\mu}$-CP 기술을 통해 poly (methylmethacrylate) (PMMA), poly (vinyl pyrrolidone) (PVP)등과 같은 유기기판 위에 고분자 패턴 형성을 하였다. 이때 전사 가능한 온도는 상온이며, 압력은 코팅된 PFDMA films이 기판과 접촉될 수 있는 정도만 필요하다. PFDMA가 상온에서 전사 가능한 이유는 유리전이온도가 상온보다 낮기 때문이다. 또한 접촉각을 측정하여 접착력을 계산하면 PFDMA와 기판과의 접착력이 상대적으로 높기 때문이다. PFDMA는 플루오르계 용매에 제거되기 때문에 유기기판의 손상을 최소화 할 수 있다. ${\mu}$-CP 기술을 이용한 PFDMA의 패턴 형성 방법은 물질의 특성으로 flexible 및 organic device 제작에 응용 될 수 있다.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.83-84
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• 1997

1. INTRODUCTION : Polyimides containing siloxane moiety(poly(imide siloxane), or polysiloxaneimide) have been synthesized because of their some merits over polyimide itseft. Polyimides have excellent thermal and mechanical properties but their poor solubility and processibility in their fullly imidized form give disadvantages in applications. Incorporation of siloxane units make it possible to increase solubility and processibility, and also impart impact resistance, low moisture uptake, low dielectric constant, thermo-oxidative resistance, good adhesion properties to substrate and etc.. Incorporation methods of siloxane groups into the polyimide was mainly copolymerization or terpolymerization between oligomeric dimethylsiloxane and aromatic dianhydride. A few methods of introducing siloxane units in functional groups of polyimide was reported. In our laboratory poly(amideimide siloxane) and poly(imide siloxane) were prepared and the study about their thermal kinetics was performed. In separation membrane area, polysiloxaneimides was utilized in pervaporation and gas separation. Polyimides in gas separation show high selectivity and very low permeability, and introduction of siloxane segments increase permeability with low decrease in selectivity. We aimed to introduce silicone segments into poly(amic acid) state and synthesize polymer partially imidized, and also show the gas separation characteristics of the synthesized polymer.