• Bulletin of the Korean Chemical Society
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• 제34권10호
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• pp.2973-2977
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• 2013

In this study, we developed a liquid crystal (LC)-based optical sensor for monitoring enzymatic activity through orientational changes in liquid crystals (LCs) coupled to the properties of a poly-${\small{L}}$-lysine (PLL)-based polymeric membrane. We prepared a PLL-based polymeric membrane at the planar interface between the thermotropic liquid crystal and aqueous phases. The PLL-based polymeric membrane was obtained by contacting the PLL solution with water immiscible LCs, 4-cyano-4'-pentyl-biphenyl (5CB) doped with adipoyl chloride. We then investigated the membrane properties by examining the permeability of the membrane to phospholipids, 1,2-didodecanoyl-rac-glycero-3-phosphocholine (DLPC). The permeability of the membrane to transport phospholipids was monitored through the orientational transition of 5CB in contact with the dispersions of DLPC. Since trypsin can enzymatically catalyze the hydrolysis of PLL, we incubated an aqueous trypsin solution with the membrane for 2 h at room temperature to cause an increase in the permeability of the polymeric membrane to DLPC. As a result, a bright to dark optical shift of LCs was observed, which implied that an enzymatic reaction between trypsin and PLL-based membrane occurred. Two control experiments using chymotrypsin and bovine serum albumin (BSA) revealed no sign of improved permeability based on the orientational transition of LCs.

• Tribology and Lubricants
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• 제4권1호
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• pp.30-35
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• 1988

Liquid crystals have some tribologically favorable lameliar structure. The Performance of ther mottopic liquid crystal was investigated under elastohydrodynamic condition in terms of traction and film thickness. It exhibited low traction and very thin film thickness, which were almost constant over the entire speed range measured. It was also found to have sealing effect like grease. This work has shown that there exists "potential" for using liquid crystals as lubricants.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.297-297
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• 2006

Recently columnar liquid crystals have been studied due to their possible application to organic conducting materials. Supramolecular columnar liquid crystals consist of mesogenic unit which can aggregate into discs that will make up the columns which associate to form a two-dimensional network. In this study, we prepared supramolecular columnar liquid crystals containing hydrogen bonding between carboxylic acid and, pyridine moieties. Thermal and structural properties of prepared complexe were investigated, and it exhibited hexagonal columnar structure ($Col_{h}$) at room temperature.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1223-1227
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• 2010

In this study, the orientational behavior of thermotropic liquid crystals (LC) supported on a film of protein receptors was examined. Avidin was roller printed and covalently immobilized onto the surface of gold using NHS/EDC chemistry. The orientation of nematic 4-cyano-4'-pentylbiphenyl (5CB) was found to be parallel to the plane of the printed avidin surface before incubation with a solution of biotin. However, protein-receptor complexation induced a random orientation of 5CB, where protein-receptor complexes disturbed the nanoscale topography of the printed protein surface. Atomic force microscopy and ellipsometry was used to confirm printing and the specific interaction of proteins. These results demonstrate that the combination of LC and roller printing can be used to detect specific interactions between biomolecules by manipulating the orientational behavior of LC to the printed protein surfaces.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3269-3273
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• 2012

In this study, we report a new method for the high contrast imaging of biomolecular interactions at roller printed protein surfaces using thermotropic liquid crystals (LCs). Avidin was roller printed and covalently immobilized onto the obliquely deposited gold surface that was decorated with carboxylic acid-terminated self-assembled monolayers (SAMs). The optical response of LCs on the roller printed film of avidin contrasted sharply with that on the obliquely deposited gold surface. The binding of biotin-peroxidase to the roller printed avidin was then investigated on the obliquely deposited gold substrate. LCs exhibited a non-uniform and random orientation on the roller printed area decorated with the complex of avidin and biotin-peroxidase, while LCs displayed a uniform and planar orientation on the area without roller printed proteins. The orientational transition of LCs from uniform to non-uniform state was triggered by the erasion of nanometer-scale topographies on the roller printed surface after the binding of biotin-peroxidase to the surface-immobilized avidin. The specific binding events of protein-receptor interactions were also confirmed by atomic force microscopy and ellipsometry. These results demonstrate that the roller printing of proteins on obliquely deposited gold substrates could provide a high contrast signal for imaging biomolecular interactions using LC-based sensors.

• 대한화학회지
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• 제50권3호
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• pp.263-268
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• 2006

• Bulletin of the Korean Chemical Society
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• 제21권3호
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• pp.310-316
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• 2000

Molecular dynamics simulation studies for thermotropic liquid crystalline systems conposed of rodlike molecules with 6 Lennard-Jones interaction sites wre performed in NPT ensemble. Within the range of temperature studied, the system exhibited isotropic and smectic phase. For the characterization of the smectic phase, we examined the structure of the liquid crystalline phase via the radial distribution function, its longitudinal and transverse components to the director, and other orientational correlation function, its longitudinal and transverse components to the director, and other orientational correlation functions. In the smectic A phase, our results showed a large anisotropy in translational motion (i.e.,$D_⊥ >> D_∥$), and the decay of the collective orientational correlation function of rank two became slower than that of the single particle orientational correlation function of rank one. Comments on the spontaneous growth of orientational order directly from the isotropic phase are given.

• 공업화학
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• 제31권3호
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• pp.305-309
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• 2020

본 연구에서는 에테르가 기능화된 이온성 액체인 [DMIm][MPEGP] (1,3-dimethylimidazolium (2-methoxy(2-ethoxy(2-ethoxy)))-ethylphosphite)와 리튬염인 LiTf₂N (lithium bis(trifluoromethanesulfonyl)imide)을 혼합하였고, 리튬염의 함량을 조절하여 전해질을 특성을 조사하였다. 제조된 전해질은 리튬염 혼합에 따라 불투명해지고 흐름성이 제한된 열방성 액정을 형성하였으며, 이때 리튬염의 함량에 따라 형성되는 이온성 액정의 자기조립구조와 이온 전도 현상을 다양한 분광학적 분석을 통해 조사하였다. 그 결과 이온성 액정의 향상된 이온전도도는 정렬된 구조를 통한 이온 전도 특성과 관계가 있음을 확인하였으며, 리튬이온전지 특성 평가에서 우수한 전기화학적 특성을 나타냄을 확인하였다.

• 대한화학회지
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• 제52권5호
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• pp.583-587
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• 2008

• Korean Chemical Engineering Research
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• 제45권2호
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• pp.155-159
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• 2007

말단에 두 개의 동일한 schiff base 메소젠과 중앙에 테트라메틸렌 유연격자를 갖는 새로운 이메소제닉 화합물을 합성하였다. 이들의 열적성질 및 액정성은 시차주사열분석기와 가열판이 부착된 편광현미경을 사용하여 조사하였다. X= -F, -Cl, -Br, -CN 및 $-OCH_3$ 화합물은 양방성 네마틱 액정이었으며, 이에 반하여 X= -I와 $-CF_3$ 화합물은 액정상을 형성하지 못하였다. 이 화합물들의 네마틱 그룹 효율은 -CN > $-OCH_3$ > -Br > -Cl > -F 순서이었다.