이 작품은 학술 연구원 교부금 번호 16H06037에 의해 지원되었다. 홋카이도 대학의 사사키 유지 사장에게 HR-DSC에 대한 기술 지원에 진심으로 감사드립니다.

1. 유리 기판 상에 퍼플 루오로 중합체의 액정 배향 층의 제조 <ol><li> 퍼플 루오로 중합체 용액의 제조 <ol><li> 퍼플 루오로 중합체 용액 (9 중량 % 중합체)을 1 : 2의 비율로 시판용 용매에 용해시켜 퍼플 루오로 중합체 용액 1 mL를 제조하고; 0.5-1μm 두께의 균일 한 막이 스핀 코팅 될 수 있습니다. 참고 : 사용 된 용액 및 솔벤트의 재료 목록을 참조하십시오. </li></ol></li><li> 깨끗한 유리 기판에 퍼플 루오로 중합체 코팅 <ol><li> 알칼리성 세제로 38 또는 42 kHz에서 초음파 처리하여 유리 기판 (일반적인 크기 : 1 cm x 1 cm)을 씻으십시오. 증류수로 반복해서 헹구십시오. 일반적으로, 매회 5 번 초음파 세척으로 10 회 이상 헹구십시오. </li><li> UV-O 3 세정제로 10 분간 기판을 채 웁니다. </li><li> 단계 1.1의 용액 20 μL를 세척 된 유리 기질에 흘려 라.테. 즉시 용액을 3,500 rpm으로 실온에서 70 초 동안 스핀 코트하십시오. 80 ° C에서 60 분 동안 필름을 베이킹하여 용제를 제거하고 200 ° C에서 60 분 동안 경화시킵니다. </li></ol></li></ol> 2. 액정 셀 준비 <ol><li> 광경 화성 수지와 파장 365 nm (1.1 W / cm 2 )의 LED 램프를 사용하여 필름으로 코팅 된 두 개의 유리 기판을 접착하십시오. 마이크로 미터 크기의 유리 입자 또는 폴리에틸렌 나 프탈레이트 필름을 사용하여 두 기판 사이의 간격을 2 ~ 100 μm 범위 내로 조정하십시오. </li><li> 등방성 액체 (I)보다 높은 온도의 모세관 력으로 주걱을 사용하여 준비된 LC 셀에 LC 물질, 4&#39;- 부틸 -4- 헵틸 - 비 시클로 헥실 -4- 카보 니트릴 (CCN47; 0.2-10 μL) - 네마 틱 (N) 상 전이 온도. 참고 : CCN47은 음의 유전율 이방성을 가지며 위상 시퀀스는 Cry 298.6 K SmA 301.3 KN 331.3 KI, 여기서 Cry 및 SmA는 결정 및 스 멕틱 A 상을 나타낸다. flow-induced alignment가 촉진되기 때문에 CCN47을 N 기 또는 SmA기에 도입하지 마십시오. </li></ol> 3. 샘플 특성화 <ol><li> 편광 광학 현미경 (POM)에 의한 조직 관찰 10 <ol><li> ± 0.1-K 정확도로 샘플 온도를 제어하는 ​​핫 스테이지와 함께 4-100X 대물 렌즈로 POM에서 LC 셀을 관측하십시오. 켈빈 당 균등 한 간격으로 5 프레임 이상의 텍스처를 기록하십시오. 냉각 및 가열시 291-343 K의 범위에서 순차적 으로 디지털 컬러 카메라를 사용하십시오. </li></ol></li><li> 유전체 분광학 (DS) 11 <ol><li> 두 기판에서 ITO 전극 (정사각형 또는 원형 모양을 가질 수 있고 상업적으로 구입할 수 있음)을 사용하여 LC 셀을 준비합니다. 리드선을 각 기판에 납땜하십시오. 참고 : 사용 된 인쇄물의 재료 목록을 참조하십시오. </li><li> 상용 임피던스 / 이득 위상 분석기를 사용하여 POM에 사용 된 것과 똑같은 LC 셀의 커패시턴스 또는 유전 상수를 측정하십시오. 각 측정 전에 시료의 상태가 평형인지 확인하십시오. 매 5 분마다 LC 셀의 정전 용량을 수동으로 측정하여 LC 셀의 정전 용량 또는 유전 상수의 시간 의존성을 측정합니다. </li><li> LC 셀의 커패시턴스 또는 유전 상수가 비 시간 종속적 인 경우에만 DS 측정을 시작하십시오. </li></ol></li><li> 고해상도 시차 주사 열량계 (HR-DSC) 12 <ol><li> LC 셀을 집에서 만든 HR-DSC에 넣고 정확하게 POM (DSC 팬을 사용 하지 마십시오) 에서처럼 검사합니다. HR-DSC를 설계 및 구축하고 사용 방법을 배우려면 참조 12를 참조하십시오. 최소 온도 분해능을 높이기 위해 0.05-0.10 K / min의 스캔 속도로 측정을 수행하십시오.어. </li></ol></li><li> 방목 입사 X 선 회절 (GI-XRD) 13 <ol><li> 온도 컨트롤러가 장착 된 GI-XRD 샘플 스테이지의 코팅 된 기판 위에 CCN47의 2 ~ 5 μL 액 적이 들어있는 샘플 또는 LC 셀 (POM 또는 DSC에 사용됨)을 넣으십시오. </li><li> 냉각 및 가열시 291-343 K 범위의 원하는 온도에서 10 분 이상 샘플을 평형시킵니다. </li><li> 분자 방향 및 배열 / 구조에 대한 표면 정보를 추출하기 위해 0.05-0.10 ° 정도의 작은 입사각으로 샘플에 입사 X- 선 빔을 사용하십시오. 회절 강도가 가장 강한 최적의 입사각을 찾기 위해 X 선 광선의 입사각을 스윙합니다. 최적의 입사각으로 측정하십시오. 참고 : GI-XRD를 사용하면 나노 미터 스케일에서 계면 특이성을 조사 할 수 있으므로 얇은 층에서 신호를 최대화 할 수 있습니다벌크에서 신호를 최소화하면서. GI-XRD 이외의 일반 XRD 구조는 X 선 방사 빔이 재료에 대한 깊이가 매우 깊기 때문에 표면에 민감하지 않습니다. </li></ol></li></ol>

<ol>
	<li>Woltman, S. J., Jay, G. D., Crawford, G. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid-Crystal+Materials+Find+a+New+Order+in+Biomedical+Applications.">Liquid-Crystal Materials Find a New Order in Biomedical Applications.</a> Nat. Mater. 6 (12), 929-938 (2007).</li><li>Carlton, R. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+and+Biological+Sensing+Using+Liquid+Crystals.">Chemical and Biological Sensing Using Liquid Crystals.</a> Liq. Cryst.Rev. 1 (1), 29-51 (2013).</li><li>Patel, J. S., Yokoyama, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+Anchoring+Transition+in+Liquid+Crystals.">Continuous Anchoring Transition in Liquid Crystals.</a> Nature. 362, 525-527 (1993).</li><li>Senyuk, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+alignment,+anchoring+transitions,+optical+properties,+and+topological+defects+in+the+nematic+phase+of+thermotropic+bent-core+liquid+crystal+A131.">Surface alignment, anchoring transitions, optical properties, and topological defects in the nematic phase of thermotropic bent-core liquid crystal A131.</a> Phys Rev E. 82 (4 Pt 1), 041711 (2010).</li><li>Bechhoefer, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+Behavior+in+Anchoring+Transitions+of+Nematic+Liquid+Crystals.">Critical Behavior in Anchoring Transitions of Nematic Liquid Crystals.</a> Phys. Rev. Lett. 64 (16), 1911-1914 (1990).</li><li>Dhara, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anchoring+Transitions+of+Transversely+Polar+Liquid-Crystal+Molecules+on+Perfluoropolymer+Surfaces.">Anchoring Transitions of Transversely Polar Liquid-Crystal Molecules on Perfluoropolymer Surfaces.</a> Phys. Rev. E. 79 (6 Pt 1), 60701 (2009).</li><li>Aya, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stepwise+heat-capacity+change+at+an+orientation+transition+in+liquid+crystals.">Stepwise heat-capacity change at an orientation transition in liquid crystals.</a> Phys. Rev. E. 86 (2), 022512 (2014).</li><li>Aya, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermodynamically+Anchoring-Frustrated+Surface+to+Trigger+Bulk+Discontinuous+Orientational+Transition.">Thermodynamically Anchoring-Frustrated Surface to Trigger Bulk Discontinuous Orientational Transition.</a> Langmuir. 32 (41), 10545-10550 (2016).</li><li>Dhara, S., Madhusudana, N. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physical+characterisation+of+4'-butyl-4-heptyl-bicyclohexyl-4-carbonitrile.">Physical characterisation of 4'-butyl-4-heptyl-bicyclohexyl-4-carbonitrile.</a> Phase Trans. 81 (6), 561-569 (2008).</li><li>Dierking, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Textures of Liquid Crystals. , (2003).</li><li>Perkowski, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technical+aspects+of+dielectric+spectroscopy+measurements+of+liquid+crystals.">Technical aspects of dielectric spectroscopy measurements of liquid crystals.</a> Opto-Electronics Review. 16 (3), 271-276 (2008).</li><li>Inaba, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nano-watt+stabilized+DSC+and+ITS+applications.">Nano-watt stabilized DSC and ITS applications.</a> J Therm Anal Calorim. 79 (3), 605-613 (2005).</li><li>Leveiller, F., Boehm, C., Jacquemain, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two-dimensional+crystal+structure+of+cadmium+arachidate+studied+by+synchrotron+X-ray+diffraction+and+reflectivity.">Two-dimensional crystal structure of cadmium arachidate studied by synchrotron X-ray diffraction and reflectivity.</a> Langmuir. 10 (3), 819-829 (1994).</li><li>de Gennes, P. G., Prost, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Physics of Liquid Crystals (Second Edition). , (1993).</li><li>Aya, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+Behavior+in+an+Electric-Field-Induced+Anchoring+Transition+in+a+Liquid+Crystal.">Critical Behavior in an Electric-Field-Induced Anchoring Transition in a Liquid Crystal.</a> Phys. Rev. E. 86 (1 Pt 1), 10701 (2012).</li><li>Avrami, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetics+of+Phase+Change.+I+General+Theory.">Kinetics of Phase Change. I General Theory.</a> J. Chem. Phys. 7, 1103-1112 (1939).</li><li>Avrami, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetics+of+Phase+Change.+II+Transformation-Time+Relations+for+Random+Distribution+of+Nuclei.">Kinetics of Phase Change. II Transformation-Time Relations for Random Distribution of Nuclei.</a> J. Chem. Phys. 8 (2), 212-224 (1939).</li><li>Avrami, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Granulation+Phase+Change,+and+Microstructure+Kinetics+of+Phase+Change.+III.">Granulation Phase Change, and Microstructure Kinetics of Phase Change. III.</a> J. Chem. Phys. 9, 177-184 (1941).</li><li>Sasaki, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinctive+Thermal+Behavior+and+Nanoscale+Phase+Separation+in+the+Heterogeneous+Liquid-+Crystal+B4+Matrix+of+Bent-Core+Molecules.">Distinctive Thermal Behavior and Nanoscale Phase Separation in the Heterogeneous Liquid- Crystal B4 Matrix of Bent-Core Molecules.</a> Phys. Rev. Lett. 107 (23), 237802 (2011).</li></ol>

저자는 공개 할 것이 없습니다.

5μm LC 셀 ( 그림 1a 및 b )을 사용하여 촬영 한 10x POM 이미지는 벌크 LC 분자의 방향 상태가 1 차 방식으로 온도 변화에 따라 P 및 V 방향 사이에서 이동 함을 명확하게 보여줍니다. 이것은 도메인 핵 생성 및 성장 과정에 의해 표시되며 새로운 방향은 초기 방향과 90 ° 다릅니다. 냉각 및 가열시의 전이 온도는 각각 321.5 K 및 325.3 K입니다. CCN47이 ~ 0.02 9 의 복굴...

최근 몇 년 동안, 외부 자극에 반응하는 표면 분자의 동적 인 분자 구조 및 구조가 LC 상태에서 물질의 벌크 배향에 어떻게 영향을 줄 수 있는지에 대한 관심이 증가 해왔다. 한 가지 예는 LC 1 , 2 의 새로운 응용으로서 LC 바이오 센서를 사용하는 것이다. 얼마나 많은 표적 생물 종이 검출되는지를 정량화하기 위해 표적 분자와 접촉하는 계면 LC가 어떻게 변화하고 진화 하는지를 알아내는 동시에 그들이 성질을 대량으로 옮기거나 번역하는 방법을 알아내는 것이 중요합니다. 모델을 사용하여 이러한 해답을 추구하면서 표면 분자 방향 및 단거리 정렬이 열역학적으로 다른 시스템으로 시작했습니다. 이 시스템을 사용하여 표면 방향 및 정렬 순서의 변경 사항을 결과적으로 대량의 방향과 체계적으로 연관시킬 수 있습니다. 최근에 우리는 o를 나타내는 몇 가지 LC 시스템을 발견했습니다.온도에 따라 자발적인 벌크 분자 배향이 변화하는 리서치 천이. 원칙적으로 방향 전환은 준 2 차 3 , 4 또는 준 1 차 천이 5 , 6 , 7 , 8 로 분류 할 수 있습니다. 전자는 온도 변화시 연속적인 분자 재배 향을 동반하지만, 후자는 불연속적인 재연성을 나타낸다. 이 기사에서는 P와 V 방향 상태 사이에서 준 1 차 방식으로 방향 전환을 설명합니다. 그것은 온도를 변화시킴으로써 단일 네마 틱 (N) 상으로 진행한다. 자세한 내용은 대표 결과 및 토론에서 제공됩니다. 벌크의 방향 변화는 표면 분자 방향의 변화와 짧은이 시스템이 표면 분자 배향과 단거리 정렬의 열역학적 변화가 벌크 배향에 어떻게 영향을 미치는지에 대한 통찰력을 잠재적으로 제공 할 수 있음은 자명하다. 이 기사에서는 위에서 언급 한 문제를 이해하기 위해 POM, DS, HR-DSC 및 GI-XRD와 같은 4 가지 보완 방법을 사용하여 세 가지 문제를 해결했습니다. (1) 방향 전환은 어떻게 생겼습니까? (2) 방향 전환이 열적으로 감지 가능한가? (3) 오리엔테이션 전환은 왜 그리고 어떻게 발생합니까?

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>CYTOP</td>
			<td>Asahi Glass Co. Ltd.</td>
			<td>CTX-809A</td>
			<td></td>
		</tr>
		<tr>
			<td>Solvent for CYTOP</td>
			<td>Asahi Glass Co. Ltd.</td>
			<td>CT-180 Sol.</td>
			<td></td>
		</tr>
		<tr>
			<td>Alkaline detergent</td>
			<td>Merck KGaA</td>
			<td>Extran MA01</td>
			<td></td>
		</tr>
		<tr>
			<td>NOA61</td>
			<td>Norland Products, Inc.</td>
			<td>#37-322</td>
			<td>Purchasable from Edmund Optics</td>
		</tr>
		<tr>
			<td>AL1254</td>
			<td>JSR Corporation</td>
			<td></td>
			<td>Planar alignment material in self-made cells</td>
		</tr>
		<tr>
			<td>4&#8217;-butyl-4-heptyl-bicyclohexyl-4-carbonitrile</td>
			<td>Nematel GmbH &#38; Co. KG</td>
			<td></td>
			<td>Custom-made</td>
		</tr>
		<tr>
			<td>UV-O3 cleaner</td>
			<td>Technovision Inc.</td>
			<td>UV-208</td>
			<td></td>
		</tr>
		<tr>
			<td>Hot-stage system</td>
			<td>Mettler Toledo</td>
			<td>HS82</td>
			<td></td>
		</tr>
		<tr>
			<td>High-Definition Color Camera Head</td>
			<td>Nikon</td>
			<td>DS-Fi1</td>
			<td></td>
		</tr>
		<tr>
			<td>Impedance/gain-phase analyzer</td>
			<td>Solartron Analytical</td>
			<td>1260</td>
			<td></td>
		</tr>
		<tr>
			<td>Indium Tin Oxide (ITO)-coated substrate</td>
			<td>GEOMATEC Co. Ltd.</td>
			<td></td>
			<td>Custom-made</td>
		</tr>
	</tbody>
</table>

orientational transition in a liquid crystal triggered by the thermodynamic growth of interfacial wetting sheets

액정 (LC) 물리 화학에서, 표면 근처의 분자는 벌크 배향을 제어하는데 큰 역할을한다. 지금까지, 주로 LC 디스플레이에서 원하는 분자 배향 상태를 달성하기 위해, LC의 &quot;정적&quot;표면 특성, 소위 표면 앵커링 (surface anchoring)이 집중적으로 연구되었다. 일반적으로 마찰이나 특정 배향막 처리와 같은 특정 표면 처리로 LC의 초기 배향이 &quot;고정&quot;되면 온도에 따라 거의 변하지 않습니다. 여기서, 우리는 온도 변화에 대한 방향 전환을 나타내는 시스템을 제시하는데, 이는 컨센서스와 충돌한다. 전환 직후 벌크 LC 분자는 고온에서 평면 (P) 배향과 저온에서 1 차 과도기 방식으로 수직 (V) 배향 사이에서 90 °의 방향 회전을 경험합니다. 우리는 편광 광학 현미경으로 열역학적 표면 고정 거동을 추적했다 (POM), 유전 분광법 (DS), 고분해능 시차 주사 열량계 (HR-DSC) 및 그레이 징 입사 X- 선 회절 (GI-XRD)에 대한 연구를 수행했으며, 표면 전이 습윤 시트는 벌크의 P 배향에 국부적으로 V 배향을 부과한다. 이 풍경은 많은 LC 시스템에서 평형 벌크 배향이 표면 국부 배향에 어떻게 영향을 받는지를 설명하는 일반적인 링크를 제공합니다. 우리의 특성화에서, POM과 DS는 LC 분자의 방향의 공간적 분포에 대한 정보를 제공함으로써 유리하다. HR-DSC는 변환에 대한 정확한 열역학적 정보에 대한 정보를 제공합니다.이 정보는 제한된 분해능으로 인해 기존 DSC 장비로 해결할 수 없습니다. GI-XRD는 표면 특유의 분자 배향 및 단거리 정렬에 대한 정보를 제공합니다. 이 논문의 목적은 transi를 보여주는 샘플을 준비하기위한 프로토콜을 제시하는 것이다.벌크와 표면 모두에서 열역학적 구조 변화가 위에서 언급 한 방법을 통해 어떻게 분석 될 수 있는지를 보여줄 수있다.

POM 이미지, DS 데이터, HR-DSC 데이터 및 GI-XRD 패턴은 온도 변화 동안, 특히 냉각 및 가열시의 방향 전환 부근에서 수집되었습니다. 그림 1 은 냉각 (가열) 중에 P (V) 방향에서 V (P) 방향 상태로의 방향 전환의 POM 관측 중에 POM 및 DS 측정에 의해 만들어진 텍스처의 진화를 나타냅니다. POM 관측 ( <strong class="xfig"...

Watch this Scientific Journal Video about Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets at JoVE.com

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

여기서는 온도에 따라 액정의 방향 전환을 트리거하는 프로토콜을 제시합니다. 전이 과정과 상세한 이행 진화를 관찰하기 위해 표본을 준비하는 방법론을 설명합니다.

계면 습윤지의 열역학적 성장에 의해 촉발 된 액정의 방향 전환

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve ...

orientational-transition-liquid-crystal-triggered-thermodynamic

Research

JoVE Journal

Engineering

7.1K 조회수.  RIKEN Center for Emergent Matter Science (CEMS).  여기서는 온도에 따라 액정의 방향 전환을 트리거하는 프로토콜을 제시합니다. 전이 과정과 상세한 이행 진화를 관찰하기 위해 표본을 준비하는 방법론을 설명합니다. 

비디오: Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

Dry Oxidation and Vacuum Annealing Treatments for Tuning the Wetting Properties of Carbon Nanotube Arrays

In this article, we describe a simple method to reversibly tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays. Here, CNT arrays are defined as densely packed multi-walled carbon nanotubes oriented perpendicular to the growth substrate as a result of a growth process by the standard thermal chemical vapor deposition (CVD) technique.1,2 These CNT arrays are then exposed to vacuum annealing treatment to make them more hydrophobic or to dry oxidation treatment to render them more hydrophilic. The hydrophobic CNT arrays can be turned hydrophilic by exposing them to dry oxidation treatment, while the hydrophilic CNT arrays can be turned hydrophobic by exposing them to vacuum annealing treatment. Using a combination of both treatments, CNT arrays can be repeatedly switched between hydrophilic and hydrophobic.2 Therefore, such combination show a very high potential in many industrial and consumer applications, including drug delivery system and high power density supercapacitors.3-5
The key to vary the wettability of CNT arrays is to control the surface concentration of oxygen adsorbates. Basically oxygen adsorbates can be introduced by exposing the CNT arrays to any oxidation treatment. Here we use dry oxidation treatments, such as oxygen plasma and UV/ozone, to functionalize the surface of CNT with oxygenated functional groups. These oxygenated functional groups allow hydrogen bond between the surface of CNT and water molecules to form, rendering the CNT hydrophilic. To turn them hydrophobic, adsorbed oxygen must be removed from the surface of CNT. Here we employ vacuum annealing treatment to induce oxygen desorption process. CNT arrays with extremely low surface concentration of oxygen adsorbates exhibit a superhydrophobic behavior.

This article describes a simple method to fabricate vertically aligned carbon nanotube arrays by CVD and to subsequently tune their wetting properties by exposing them to vacuum annealing or dry oxidation treatment.

탄소 나노 튜브 배열의 으러 속성을 조정을위한 트리트먼트 소둔 건식 산화, 진공

In this article, we describe a simple method to reversibly  tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays.  Here, CNT ...

연구

공학

Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using sputtering techniques. Here we describe a method for preparing epitaxial thin films of B2-ordered FeRh by sputter deposition onto single crystal MgO substrates. Deposition at a slow rate onto a heated substrate allows time for the adatoms to both settle into a lattice with a well-defined epitaxial relationship with the substrate and also to find their proper places in the Fe and Rh sublattices of the B2 structure. The structure is conveniently characterized with X-ray reflectometry and diffraction and can be visualised directly using transmission electron micrograph cross-sections. B2-ordered FeRh exhibits an unusual metamagnetic phase transition: the ground state is antiferromagnetic but the alloy transforms into a ferromagnet on heating with a typical transition temperature of about 380 K. This is accompanied by a 1% volume expansion of the unit cell: isotropic in bulk, but laterally clamped in an epilayer. The presence of the antiferromagnetic ground state and the associated first order phase transition is very sensitive to the correct equiatomic stoichiometry and proper B2 ordering, and so is a convenient means to demonstrate the quality of the layers that can be deposited with this approach. We also give some examples of the various techniques by which the change in phase can be detected.

A method to prepare epitaxial layers of ordered alloys by sputtering is described. The B2-ordered FeRh compound is used as an example, as it displays a metamagnetic transition that depends sensitively on the degree of chemical order and the exact composition of the alloy.

Metamagnetic B2-주문 FeRh 에피 층의 스퍼터 성장과 특성

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using ...

Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via stereotactic radiotherapy where positioning accuracy allows delivering very high doses per fraction in a small volume of the patient. Dosimetric measurements on medical accelerators are conventionally realized using air-filled ionization chambers. However, in small beams these are subject to nonnegligible perturbation effects. This study focuses on liquid ionization chambers, which offer advantages in terms of spatial resolution and low fluence perturbation. Ion recombination effects are investigated for the microLion detector (PTW) used with the Cyberknife system (Accuray). The method consists of performing a series of water tank measurements at different source-surface distances, and applying corrections to the liquid detector readings based on simultaneous gaseous detector measurements. This approach facilitates isolating the recombination effects arising from the high density of the liquid sensitive medium and obtaining correction factors to apply to the detector readings. The main difficulty resides in achieving a sufficient level of accuracy in the setup to be able to detect small changes in the chamber response.

A growing number of radiation therapy devices offer the advantage of delivering the dose through very small beams to the tumor, allowing for increased conformity and higher doses per fraction. Many different detectors can be used for the dosimetry of these small fields. In the present study, the effect of ion recombination is investigated for a liquid ionization chamber using a stereotactic radiation therapy system.

액체 이온화 챔버의 재조합 효과의 특성은 Radiosurgical 가속기의 선량 측정에 사용

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via ...

Ultrasound Velocity Measurement in a Liquid Metal Electrode

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently more difficult than measuring the flow of a transparent fluid, since optical methods are not applicable. Ultrasound can be used to measure the velocity of an opaque fluid, not only at isolated points, but at hundreds or thousands of points arrayed along lines, with good temporal resolution. When applied to a liquid metal electrode, ultrasound velocimetry involves additional challenges: high temperature, chemical activity, and electrical conductivity. Here we describe the experimental apparatus and methods that overcome these challenges and allow the measurement of flow in a liquid metal electrode, as it conducts current, at operating temperature. Temperature is regulated within &#177;2 &#176;C using a Proportional-Integral-Derivative (PID) controller that powers a custom-built furnace. Chemical activity is managed by choosing vessel materials carefully and enclosing the experimental setup in an argon-filled glovebox. Finally, unintended electrical paths are carefully prevented. An automated system logs control settings and experimental measurements, using hardware trigger signals to synchronize devices. This apparatus and these methods can produce measurements that are impossible with other techniques, and allow optimization and control of electrochemical technologies like liquid metal batteries.

Ultrasound velocimetry is used to study mixing by fluid flow in liquid metal electrodes. The focus of this manuscript is to illustrate the methods used for making precise, spatially-resolved ultrasound measurements while limiting oxidation and controlling and monitoring temperature, applied current, and the heater power being supplied.

액체 금속 전극의 초음파 속도 측정

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently ...

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

액체 환경에서의 펄스 자외선 레이저 조사에 의한 실리콘 표면의 젖음성의 선택 영역 수정

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators &#8212; a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes.

This movie shows how an atmospheric plasma torch can be ignited by microwaves with no additional igniters and provides a stable and continuous plasma operation suitable for plenty of applications.

어떻게 추가 점화기없이 대기압 마이크로 웨이브 플라즈마 토치를 점화

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a ...

How to Build a Vacuum Spring-transport Package for Spinning Rotor Gauges

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to 1.0 Pa. In this application, the SRGs are frequently transported to laboratories for calibration. Events can occur during transportation that change the rotor surface conditions, thus changing the calibration factor. To assure calibration stability, a spring-transport mechanism is often used to immobilize the rotor and keep it under vacuum during transport. It is also important to transport the spring-transport mechanism using packaging designed to minimize the risk of damage during shipping. In this manuscript, a detailed description is given on how to build a robust spring-transport mechanism and shipping container. Together these form a spring-transport package. The spring-transport package design was tested using drop-tests and the performance was found to be excellent. The present spring-transport mechanism design keeps the rotor immobilized when experiencing shocks of several hundred g (g = 9.8 m/sec2 and is the acceleration due to gravity), while the shipping container assures that the mechanism will not experience shocks greater than about 100 g during common shipping mishaps (as defined by industry standards).

Here we describe how to build a robust spring-transport mechanism for a spinning rotor gauge. This device securely immobilizes the rotor and keeps it under vacuum during transportation. We also describe packaging that minimizes the risk of damage during transport. Tests show our design works for typical shocks during transport.

어떻게 로터 게이지를 회전하기위한 진공 봄 전송 패키지를 빌드하는 방법

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to ...

Preparation of Liquid-exfoliated Transition Metal Dichalcogenide Nanosheets with Controlled Size and Thickness: A State of the Art Protocol

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. Layered crystals of molybdenum disulphide (MoS2) and tungsten disulphide (WS2) are exfoliated in aqueous surfactant solution by sonication. This yields highly polydisperse mixtures containing nanosheets with broad size and thickness distributions. However, for most purposes, specific sizes (in terms of both lateral dimension and thickness) are required. For example, large and thin nanosheets are desired for (opto) electronic applications, while laterally small nanosheets are interesting for catalytic applications. Therefore, post-exfoliation size selection is an important step that we address here. We provide a detailed protocol on the efficient size selection in large quantities by liquid cascade centrifugation and the size and thickness quantification by statistical microscopic analysis (atomic force microscopy and transmission electron microscopy). The comparison of MoS2 and WS2 shows that both materials are size-selected in a similar way by the same procedure. Importantly, the dispersions of size-selected nanosheets show systematic changes in their optical extinction spectra with size due to edge and confinement effects. We show how these optical changes are related quantitatively to the nanosheets dimensions and describe how mean nanosheets length and layer number can be extracted reliably from the extinction spectra. The exfoliation and size selection protocol can be applied to a broad range of layered crystals as we have previously demonstrated for graphene, gallium sulphide (GaS) and black phosphorus.

A protocol for the liquid exfoliation of layered materials to nanosheets, their size selection and size measurement by microscopic and spectroscopic techniques is presented.

액체 박리 전이 금속 Dichalcogenide 제어 된 크기와 나노 시트와 두께의 준비 : 예술 프로토콜의 주

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. ...

Preparation of Liquid Crystal Networks for Macroscopic Oscillatory Motion Induced by Light

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous light irradiation. The photo-excitation of dopants that can quickly dissipate light into heat, coupled with anisotropic thermal expansion and self-shadowing of the film, gives rise to the self-sustained deformation. The oscillations observed are influenced by the dimensions and the modulus of the film, and by the directionality and intensity of the light. The system developed offers applications in energy conversion and harvesting for soft-robotics and automated systems.
The general method described here consists of creating free-standing liquid crystalline films and characterizing the mechanical and thermal effects observed. The molecular alignment is achieved using alignment layers (rubbed polyimide), commonly used in the display manufacturing industry. To obtain actuators with large deformation, the mesogens are aligned and polymerized in a splay/bend configuration, i.e., with the director of the liquid crystals (LCs) going gradually from planar to homeotropic through the film thickness. Upon irradiation, the mechanical and thermal oscillations obtained are monitored with a high-speed camera. The results are further quantified by image analysis using an image processing program.

The goal of the protocol is to create liquid crystalline polymer films that can mechanically oscillate under continuous light irradiation. We describe in great detail the conception of free-standing films, from the liquid crystal alignment method to the photo-actuation. The experimental protocol applied to prepare this material is broadly applicable.

빛에 의해 유도 된 거시적인 진동 모션 액정 네트워크의 준비

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous ...

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition metal dichalcogenides (TMDs) MoS2 and WS2 can be prepared on sapphire substrates. By controlling the metal film thicknesses, good layer number controllability, down to a single layer of TMDs, can be obtained using this growth technique. Based on the results obtained from the Mo film sulfurized under the sulfur deficient condition, there are two mechanisms of (a) planar MoS2 growth and (b) Mo oxide segregation observed during the sulfurization procedure. When the background sulfur is sufficient, planar TMD growth is the dominant growth mechanism, which will result in a uniform MoS2 film after the sulfurization procedure. If the background sulfur is deficient, Mo oxide segregation will be the dominant growth mechanism at the initial stage of the sulfurization procedure. In this case, the sample with Mo oxide clusters covered with few-layer MoS2 will be obtained. After sequential Mo deposition/sulfurization and W deposition/sulfurization procedures, vertical WS2/MoS2 hetero-structures are established using this growth technique. Raman peaks corresponding to WS2 and MoS2, respectively, and the identical layer number of the hetero-structure with the summation of individual 2D materials have confirmed the successful establishment of the vertical 2D crystal hetero-structure. After transferring the WS2/MoS2 film onto a SiO2/Si substrate with pre-patterned source/drain electrodes, a bottom-gate transistor is fabricated. Compared with the transistor with only MoS2 channels, the higher drain currents of the device with the WS2/MoS2 hetero-structure have exhibited that with the introduction of 2D crystal hetero-structures, superior device performance can be obtained. The results have revealed the potential of this growth technique for the practical application of 2D crystals.

Through the sulfurization of pre-deposited transition metals, large-area and vertical 2D crystal hetero-structures can be fabricated. The film transferring and device fabrication procedures are also demonstrated in this report.

큰 지역 수직 2D 크리스탈 Hetero-구조 장치 제조에 전이 금속 영화 Sulfurization의 준비

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition ...