The authors wish to acknowledge the competitive faculty-initiated collaboration (FIC) grant from KAUST.

PR-도핑 된 SrTiO3 3 분말 1. 준비 <ol><li> SrCO 3 분말 (7.53407 G), 이산화 티탄 나노 분말 (4.28983 G), 및 PR의 이론 양, 산화 티타늄 3 잠 0.05 0.95 시니어 분말 10g을 준비 무게를하기 위해 2 O 반응 다음의 3 소결 덩어리 (0.44299 G) X = 0.05에 대한 : </li></ol><img alt="식 (1)" fo:content-width="5in" src="/files/ftp_upload/52869/52869eq1.JPG" width="550" /><ol start="2"><li> 마노 박격포와 유 봉을 사용하여 미세 입자의 무게 잠 2 O 3 소결 덩어리를 갈기. </li><li> 잠 2 O 3에 무게 SrCO 3 분말과 이산화 티탄 나노 분말을 추가하고 연마 및 시각적으로 균일 한 분말을 얻을 때까지 마노 박격포와 유 봉을 사용하여 혼합 계속합니다. </li><li> 유리 항아리로 분쇄 물을 넣고 30 분 째 균질화하는 난류 혼합을 사​​용전자 혼합물. </li><li> 꼼꼼하게 청소 및 광택 스테인레스 스틸 다이 (직경 1 인치)로 생성 된 혼합 분말을 넣고 두 개의 스테인레스 스틸 플런저 사이를 샌드위치. </li><li> 콜드 프레스 약 1 메트릭 톤의 하중 프레스를 사용하여 분말. </li><li> 중공 스테인리스 스틸 실린더에 다이를 배치하고 가압로드를 사용하여 상부로부터 플런저 펠렛을 누름으로써 초기 가압 펠릿을 꺼내고. 다이로부터 냉간 펠릿 (성형체)의 토출 후, 부드럽게 스카치 테이프의 작은 조각으로 펠릿을 피복 테이프를 리핑하여 얇은 층을 제거하여 펠릿의 외주 표면상의 오염을 청소. </li><li> 알루미나 보트와 추위를 눌러 펠렛 사이의 장벽으로 상업적으로 구입 SrTiO3를 분말로 가득 알루미나 보트에 수직으로 펠렛을 놓습니다. </li><li> , 튜브로에서 보트를 놓고 3 시간에 1,300 ° C까지 가열 (15)이 온도에서 보관시간. 소성이 끝나면 펠릿 보일러 내부에서 실온까지 냉각시킵니다. 이 단계 후, &quot;소성 과정&quot;이라 칭한다. </li><li> 마노 박격포와 유 봉을 사용하여 펠렛을 갈기 더욱 난류를 사용하여 혼합 유리 항아리에 생성 된 분말을로드합니다. </li><li> 부하의 약 3 톤에서 누른 스테인레스 스틸 다이 및 감기에 가루를 넣습니다. </li><li> 3 시간에 1,400 ° C에서 단계를 1.9 한 번 더 반복하고 20 시간 동안이 온도에서 보관하십시오. </li><li> 마노 박격포와 유 봉을 사용하여 펠렛을 갈기. </li><li> 반복 고체 상태 반응이 완성에 도달하기위한 1.11, 1.12, 1.13을 한 번 더 반복합니다. </li></ol> 대량 다결정 PR-도핑 된 SrTiO3 3 세라믹 2. 준비 <ol><li> (2 mm 두께와 직경 12.7 mm의 디스크)으로 제조 된 분말 1.6 g의 무게. </li><li> 상하 INTE 다루 graphoil 원형 조각을 준비흑연 다이에 끼워 분말과 흑연 플런저 rface. 또한, 흑연 몰드의 내벽을 덮도록 다른 직사각형 graphoil 조각을 준비한다. </li><li> 흑연 다이 도입부로서 준비된 분말 (내경 12.7 mm)을로드하고 동일한 크기의 두 개의 플런저 사이 흑연 분말 샌드위치. 흑연 다이의 길이의 중간에 2 mm의 구멍을 드릴과 다이의 외면 온도 판독에 대한 내부 표면의 약 2mm이다. 참고 : 다이 외부에 남아있는 흑연 플런저의 길이를 조정하고 구멍이 정확한 온도 독서를 얻기 위해 배치 된 샌드위치 분말 실린더의 중심에 위치. 흑연 플런저의 얼굴은 심하게 조각의 가공 중에 평준화 될 필요가있다. 모든 어긋남은 스파크 플라즈마 소결시 소결 펠릿의 균열이 발생할 수 있습니다. </li><li> 콜드 프레스 스파크에 장착하기 전에 프레스를 사용하여 분말 부드럽게 (부하 &lt;200kg)챔버 내부의 플라즈마 소결 판. 흑연 플런저 손상을 방지하기 위해 상단과 하단 플런저 및 언론 단계 사이의 평면 광택 스테인레스 스틸지지 플레이트를 사용합니다. </li><li> 흑연 조각 절연의 다이 주위 느꼈다 랩과 흑연 원사로 고정합니다. 온도 판독 홀이 다이 상에 배치 된 펠트의 직사각형 조각을 절단하여 흑연 펠트에 창을 고안. </li><li> 방전 플라즈마 소결 챔버로드 흑연 몰드 플런저를 놓는다. 최종 위치로 무대를 이동합니다. </li><li> 초점 및 다이의 온도 판독 홀 고온계 목표 원을 정렬. 고온계의 방사율 설정이 흑연에 대해 설정되어 있는지 확인합니다. </li><li> 챔버를 닫고 샘플에 7.7 KN 하중 (약 60 MPa의)를 넣습니다. 진공 및 아르곤으로 3 회 퍼지 챔버 6 파의 동적 진공하에 챔버를 떠난다. </li><li> 수동 전류 (또는 증가를 이용하여 온도를 상승프로그램). 250 분 -1 사용 (에 대응을 약 300 ~ 400 ° C의 분 -1) 최적화 된 샘플. 이 방전 플라즈마 소결 공정의 가장 중요한 단계이다. </li><li> 수동 전류를 조정 또는 프로그램을 사용하여 5 분 동안 1500 ° C의 온도에서 유지. 5 분간 보유 기간이 종료되면, 냉각 중에 시료 분해 피하기 위해 7.7 KN 부하를 신속하게 방출 전류를 차단하고. 챔버 내부 RT에 샘플 멋진하자. </li><li> 부드럽게 감기 프레스를 사용하여 다이 흑연에서 대량 펠렛을 놓습니다. 이는 중공 스틸 실린더에 흑연 다이를 배치하고 펠렛 위에서로드를 밀어 스틸을 사용 흑연 플런저를 토출함으로써 행해진 다. </li><li> 날카로운 면도날을 이용하여 펠릿 리면뿐만 아니라 내주면에 graphoil 제거. </li><li> 보증하기 위해 각각의 측면에서 거친 사포 실망 0.3~0.5 mm 대 (400 눈금)를 사용하여 샘​​플을 폴란드어graphoil의 완전한 제거. 아세톤 샘플을 청소합니다. </li></ol> 대량 도자기 3. 전자의 특성 및 열전달 특성 <ol><li> 아르키메데스 법을 이용하여, 세라믹 디스크, ρ의 밀도를 결정한다. </li><li> 시료의 중량을 측정하여 W 건조한 다음, 물에 잠긴 시료의 중량 W 안정화 밀도 측정 시스템에 젖은로부터 아르키메데스 밀도를 계산할 </li></ol><img alt="식 (2)" fo:content-width="2.1in" src="/files/ftp_upload/52869/52869eq2.JPG" width="260" /> ρ 물 측정 온도에서 물의 밀도이다. (14) (예 1, g cm -3 300 K에서와 동일) <ol start="2"><li> 아르곤의 75 mL의 분 -1 흐름 하에서 과도 레이저 플래시 기법을 이용하여, 시료 (D)의 열 확산율 측정. 두께를 측정샘플, L의, 정확하게 먼저 디지털 마이크로 미터를 사용하여. 참고 : 다른 크기와 모양 (예를 들어, 원형 디스크 직경 또는 정사각형 10 × 10mm 2 개의 디스크에 12.7 ㎜)와 두께의 병렬 얼굴의 샘플을 쉽게 측정 할 수 MM 0.5 내지 5. <ol><li> 레이저 플래시 열확산 기법에서, 단편 (~ 1 밀리 초)의 레이저 펄스에 의해 시료의 한쪽면을 조사하고 적외선 검출기에 의해 대향면에 온도 상승을 기록한다. 그런 다음 시료의 두께와 후드 (15) 방정식을 이용하여 온도 상승 시간 프로필에서 레이저 플래시 인터페이스 소프트웨어에 의해 열 확산율을 계산할 </li></ol></li></ol><img alt="식 (3)" fo:content-width="1.9in" src="/files/ftp_upload/52869/52869eq3.JPG" width="220" /> 여기서, L은 디스크 및 t의 1/2의 두께는 다른 (S)의 최대 온도 상승의 절반 시간이다샘플의 IDE. 주 : 파커 모델 (15)은 단열 샘플과, 다른 모델은 열 손실, 유한 펄스 지속 기간, 불균일 펄스 가열 및 비균질로서 측정 각종 손실을 고려 년 동안 제안되어 순간 펄스 가열 이상적인 조건을 가정 구조. 우리는 가장 진보 된 방법 중 하나 인 펄스 보정 코완 모델 (16)을 사용했다. 이 IR 검출기에 의해 관측 된 신호를 정면으로부터 전달 된 열 에너지의 양을 최대화하고 최대화하기 위해, 샘플 표면이 고도로 방출되어야한다는 점에 유의해야한다. 일반적으로이 샘플 표면에 흑연의 얇은 코팅의 적용을 필요로한다. 열 확산율의 측정에서 2 % -5 %의 불확실성 차원의 결정에서 발생하는, 존재한다. (17) <ol start="3"><li> 직사각형 막대 형태로 다이아몬드 톱을 사용하여 디스크 펠렛을 잘라 2 × 2 ×3 mm, 전기 전도도와 제벡 계수의 측정뿐만 아니라, 사각형 디스크, 4 고온 비열 및 얇은 직사각형 조각에 대한 X 4 X 1.5 mm 3, 홀 측정을위한 8 × 5 × 1mm 3. </li><li> 평탄하고 경면 정사각형 조각 샘플의 비열, C의 P를 측정 (4 × 4 × 1.5 mm 3) 아르곤 기류 하에서, 시차 주사 열량계 (DSC)를 사용. 18 <ol><li> 정확한 냉각 속도로, 샘플을 500 ° C로 20 K 분 -1 가열 속도까지 이어 열적 평형에 도달 할 수 있도록 10 분 동안 등온 유지를 위해 40 ° C 5 K 분 -1까지의 가열 속도를 사용 이는 하였다. 아르곤 기류 하에서 측정을 수행한다 (50 ㎖ 분 -1 제안된다). </li></ol></li></ol> 인해, 분석에 사용되는 방법의 감도에 대한 열 용량을 결정하기 위해 3 회 측정을 실시 참고<html> 공지 C의 P와 (사파이어와 같은) 표준 재료의 비열 (2) 측정 시료의 비열 (3) 측정, (1)베이스 라인 측정이 배경을 감산하도록 포함된다. 샘플 평면 거울 연마 (알과 함께이 작품에 사용 된 2 O 3 도가니 백금 / Rh를 팬) 측정 도가니의 바닥 이상적인 접촉을하기 위해 있는지 확인합니다. DSC 스테이지의 정확한 구조에 대한 자세한 내용은, DSC에 외 기술 및 시료를 측정하기위한 정확한 명령들의 비교는 다양한 출처에서 찾아 볼 수있다. (19) <ol start="5"><li> 20을 사용 ρ, 열확산, D, 비열, C P 및 밀도의 측정 값으로부터 시료의 고온 열전도, κ을 계산 </li></ol>/52869/52869eq4.JPG &quot;폭 =&quot;200 &quot;/&gt; <ol start="6"><li> 금 접시 샘플로부터 절단 2 × 2 × 10mm 세 조각에 프로브 접점 (4 콘택트)은 접촉 저항의 문제를 완화하기 위하여. <ol><li> 단, 원하는 접촉 면적에 금 스퍼터링하기 위해, 2 × 2 × 10mm 3 샘플 주위 스카치 테이프 스텐실로 사용할 랩. 2 얼굴이 취소 덮인 2 × 2mm를 남겨주세요. 면도날을 사용하여, 프로브의 거리에 의해 분리 된 라인을 따라 2 × 10mm이면의 중앙에 구멍이 매우 작은 (직경 약 1mm)를 잘라. </li><li> 벤치 탑 금 스퍼터링 장치를 이용하여 ~ 200 nm 두께의 금 막을 스퍼터. 21 </li></ol></li><li> 22,23 온도의 함수로서 샘플의 전기 수송 특성, 즉 전기 전도도와 제벡 계수)을 측정한다. <ol><li> 4 단자 법을 이용하여 전기 전도도를 측정한다. SAM의 지벡 계수를 측정두 개의 중간 열전대 &quot;프로브&quot;를 통해 온도 및 전압의 측정을 사용하여 전자 설정. 디지탈 현미경을 사용하여 이러한 두 프로브들 사이의 거리를 측정한다. 전기 전송 측정에 대한 자세한 내용은 다른 곳에서 찾을 수있다. (22, 23) </li></ol></li><li> 물성 측정 시스템을 사용하여 5 × 8 × 1mm 3 샘플 온도의 함수로서 홀 캐리어 농도를 측정한다. (24) </li></ol>

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The authors have nothing to disclose.

이 프로토콜에서, 우리는 성공적으로 향상된 전자 및 열전 특성을 나타내는 벌크 다결정 PR-도핑 된 SrTiO3를 세라믹을 제조하기 위해 합성 전략의 단계를 제안 하였다. 프로토콜의 주요 단계는 하이로로서 준비된 분말을 치밀화 (I) 대기압 방전 플라즈마 소결법의 기능 (ⅱ) 복용 이점을 공기에 도핑 된 SrTiO3 3 분말의 고상 합성을 포함 벌크 세라믹스 동시에 밀도는 더 잠 가진 샘플?...

산화물 열전은 전자 수송 특성에 대한 안정성 및 비용 관점에서 고온 열전 애플리케이션을위한 유망한 후보로 나타났다. n 형 산화물 열전기 중에서 고농도 도핑 된 티탄산 스트론튬 (STO)를 인해 흥미로운 전기적 성질에 많은 관심을 끌고있다. 그러나, 큰 총 열 전도성 (κ ~ 12 W M -1 K -1 (300) 단결정에 대한 K에서) (1)과 낮은 캐리어 이동도 (μ ~ 6cm 2 V -1 초 -1 단결정 300 K에서) 한 악영향 메리트 차원 도면에 의해 평가된다 열전 성능에 영향을 미치는, 도전율 σ α는 제벡 계수이고, ZT = α이 σT / κ는, T 켈빈 절대 온도, 총 열전도율 κ. 우리는 본원에서 역률 같은 분자를 정의 PF = α 263; T. (SiGe와 합금과 같은) 다른 고온 열전기과 경쟁이 산화물 열전 재료 위해서는, 역률 및 / 또는 격자 열 전도도의 감소에 더 현저한 증가가 요구된다. STO의 열전 특성을 향상시키기 위해 실험 연구의 대부분은 주로 변형 필드와 포논의 질량 변동 산란 통한 열전도율의 감소에 초점을 맞추고있다. 이러한 시도는 다음을 포함한다 : (i) 단일 또는 이중의 Sr 도핑 2+ 또는 / 및 Ti 4+ 사이트,이 방향에 대하여 주된 노력으로서, 자연 초 격자 Ruddlesden-포퍼 구조의 2,3- (II)의 합성 상기 나노 크기의 제 2상의 SrO를 첨가하여 층, (4) 및 (iii) 복합 공학 절연막을 통해 열전 도성을 감소시키기 위해. 5 단, 최대 최근까지 더 개선 전략 substant보고되지 않았다ially 이들 산화물에 열전 역률을 증가시킨다. 벌크 단일 및 다결정 STO에서보고 된 최대 역률 (PF) 값 PF &lt;1.0 m의 W -1 K -1의 상한에 국한되어왔다. 합성 방법 및 처리 기술의 다양한 시도 상기 아이디어를 구현하는 데 사용되어왔다. 분말 합성 경로는 종래의 고상 반응을 포함 6 졸겔 7 종래 소결 반면 열수, 8 및 연소 합성, 9, 6 핫 프레스 (10)와 최근에 방전 플라즈마 소결 (12)로 분말을 조밀화하는데 사용되는 공통 기술들이다 대량 도자기. 그러나 유사한 불순물 (예를 들어, 라)와 도핑 농도, 그 결과 대량 세라믹 전자 및 열 수송 특성의 범위를 나타낸다. 이는 된 SrTiO3 &lt;공정의 강하게 의존 결함 화학 대형 인합성에 의존하는 특성을 초래 부&gt; 3. 열전 전송 혜택을 합성 및 처리 매개 변수를 최적화 보고서의 소수는있다. 그것은 때문에 아주 작은 포논에 SrTiO3를 무료 경로 (300 K에서 L 산도 ~ 2 나노 미터)을 의미하는 것으로 언급 할 가치가있다, 11 나노 구조는 주로 감소를 통해 대량 STO 도자기의 TE 성능의 개선을위한 실행 가능한 옵션이 아니다 격자 열 전도도. 최근에, 우리는 동시에 강화 된 화력 요인에서 발생하는 비 균일 PR-도핑 된 SrTiO3 3 도자기의 장점의 열전 그림의 30 % 이상 향상을보고이 상세한 비디오 프로토콜에서 열전도. 12, 13 감소, 우리가 제시하고 이들의 제조에 대한 우리의 합성 전략의 단계 논의 향상된 전자 및 열전 특성을 나타내는 STO 세라믹스 잠을 도핑.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>SrCO3 Powder, 99.9%</td>
			<td>Sigma Aldrich</td>
			<td>472018</td>
			<td></td>
		</tr>
		<tr>
			<td>TiO2 Nanopowder, 99.5%</td>
			<td>Sigma Aldrich</td>
			<td>718467</td>
			<td></td>
		</tr>
		<tr>
			<td>Pr2O3 Sintered Lumps, 99.9%</td>
			<td>Alfa Aesar</td>
			<td>35663&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Name of&#160; Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Spark Plasma Sintering&#160;</td>
			<td>Dr. Sinter Lab</td>
			<td>SPS-515S</td>
			<td></td>
		</tr>
		<tr>
			<td>Resistivity/Seebeck Coefficient Measurement System</td>
			<td>Ulvac-Riko</td>
			<td>ZEM-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Laser Flash Thermal Diffusivity Measurement System</td>
			<td>Netzsch</td>
			<td>LFA-457 Microflash</td>
			<td></td>
		</tr>
		<tr>
			<td>Differential Scanning Calorimetry (DSC) System</td>
			<td>Netzsch</td>
			<td>404C Pegasus</td>
			<td></td>
		</tr>
		<tr>
			<td>Physical Property Measurement system (PPMS)</td>
			<td>Quantum Design</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Field Emission Scanning Electron Microscope (FE-SEM)</td>
			<td>Hitachi</td>
			<td>SU-6600</td>
			<td></td>
		</tr>
		<tr>
			<td>Energyy-dispersive X-ray Spectroscopy (EDS)</td>
			<td>Oxford Instruments</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>X-ray Diffractometer</td>
			<td>Rigaku</td>
			<td>Ultima IV</td>
			<td></td>
		</tr>
		<tr>
			<td>Bench-top Sputter Coater</td>
			<td>Denton Vacuum</td>
			<td>Desk II</td>
			<td></td>
		</tr>
		<tr>
			<td>Diamond&#160; Wheel Saw</td>
			<td>South Bay Technology</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

synthesis of non-uniformly pr-doped srtio3 ceramics and their thermoelectric properties

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma sintering techniques. Polycrystalline ceramics possessing a unique morphology can be achieved by optimizing the process parameters, particularly spark plasma sintering heating rate. The phase and morphology of the synthesized ceramics were investigated in detail using X-ray diffraction, scanning electron microcopy and energy-dispersive X-ray spectroscopy. It was observed that the grains of these bulk Pr-doped SrTiO3 ceramics were enhanced with Pr-rich grain boundaries. Electronic and thermal transport properties were also investigated as a function of temperature and doping concentration. Such a microstructure was found to give rise to improved thermoelectric properties. Specifically, it resulted in a significant improvement in carrier mobility and the thermoelectric power factor. Simultaneously, it also led to a marked reduction in the thermal conductivity. As a result, a significant improvement (> 30%) in the thermoelectric figure of merit was achieved for the whole temperature range over all previously reported maximum values for SrTiO3-based ceramics. This synthesis demonstrates the steps for the preparation of bulk polycrystalline ceramics of non-uniformly Pr-doped SrTiO3.

X 선 회절 패턴 된 SrTiO3으로 된 SrTiO3에 잠의 용해도가 3 격자 PR-도핑의 효과를 연구하기 위하여 같은 제조 된 분말 및 PR 함량의 함수로서 대응하는 벌크 세라믹스 (도 1)에 대해 수집 된 3 차 위상 (들)의 형성. 패턴은 반사 공간 군 (도 1a)와 입방 격자에 연동 될 수있는 모든 같이 제조 된 분말의 SrTiO3를 위상의 형성을 확인한다. 홍보 컨텐츠를 증가 (...

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Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

A protocol for the synthesis and processing of polycrystalline SrTiO3 ceramics doped non-uniformly with Pr is presented along with the investigation of their thermoelectric properties.

불균일 PR-도핑 된 SrTiO3의 합성<sub&gt; 3</sub&gt; 도자기와 그 열전 특성

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma ...

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JoVE Journal

Chemistry

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

9.7K 조회수.  Clemson University. A protocol for the synthesis and processing of polycrystalline SrTiO3 ceramics doped non-uniformly with Pr is presented along with the investigation of their thermoelectric properties.

비디오: Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents

Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. Isonicotinic acid, or its derivatives, are coupled to variable length diaminoalkane chains under an inert atmosphere in anhydrous DMF or DMSO with the use of a weak base, triethylamine, and a coupling agent, 1-propylphosphonic anhydride. The products precipitate from solution upon formation or can be precipitated by the addition of water. If desired, the ligands can be further purified by recrystallization from hot water. Dinuclear platinum complex synthesis using the bispyridine ligands is done in hot water using transplatin. The most informative of the chemical characterization techniques to determine the structure and gross purity of both the bispyridine ligands and the final platinum complexes is 1H NMR with particular analysis of the aromatic region of the spectra (7-9 ppm). The platinum complexes have potential application as anticancer agents and the synthesis method can be modified to produce trinuclear and other multinuclear complexes with different hydrogen bonding functionality in the bridging ligand.

This protocol describes the use of amide coupling reactions of isonicotinic acid and diaminoalkanes to form bridging ligands suitable for use in the synthesis of multinuclear platinum complexes, which combine aspects of the anticancer drugs BBR3464 and picoplatin.

이핵 항암제로 플래티넘 비스 피리딘 계 리간드와 이들 착물의 합성 아미드 커플 링 반응

Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. ...

연구

화학

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis. The cyclic polymer exhibits multiple-mode diffusion which is distinct from its linear counterpart. The results demonstrate that the diffusional heterogeneity of polymers that is often hidden behind ensemble averaging can be revealed by the efficient synthesis of the cyclic polymers using the ESA-CF process and the quantitative analysis of the diffusive motion at the single molecule level using the MSD and CDF analyses.

A protocol for the synthesis and characterization of diffusive motion of cyclic polymers at the single molecule level is presented.

단일 분자 수준에서 순환 고분자의 합성 및 용융 상태에서 그들의 확산 운동의 특성

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single ...

Synthesis and Characterization of Fe-doped Aluminosilicate Nanotubes with Enhanced Electron Conductive Properties

The goal of the protocol is to synthesize Fe-doped aluminosilicate nanotubes of the imogolite type with the formula (OH)3Al2-xFexO3SiOH. Doping with Fe aims at lowering the band gap of imogolite, an insulator with the chemical formula (OH)3Al2O3SiOH, and at modifying its adsorption properties towards azo-dyes, an important class of organic pollutants of both wastewater and groundwater.
Fe-doped nanotubes are obtained in two ways: by direct synthesis, where FeCl3 is added to an aqueous mixture of the Si and Al precursors, and by post-synthesis loading, where preformed nanotubes are put in contact with a FeCl3&#8226;6H2O aqueous solution. In both synthesis methods, isomorphic substitution of Al3+ by Fe3+ occurs, preserving the nanotube structure. Isomorphic substitution is indeed limited to a mass fraction of ~1.0% Fe, since at a higher Fe content (i.e., a mass fraction of 1.4% Fe), Fe2O3 clusters form, especially when the loading procedure is adopted. The physicochemical properties of the materials are studied by means of X-ray powder diffraction (XRD), N2 sorption isotherms at -196 &#176;C, high resolution transmission electron microscopy (HRTEM), diffuse reflectance (DR) UV-Vis spectroscopy, and &#950;-potential measurements. The most relevant result is the possibility to replace Al3+ ions (located on the outer surface of the nanotubes) by post-synthesis loading on preformed imogolite without perturbing the delicate hydrolysis equilibria occurring during nanotube formation. During the loading procedure, an anionic exchange occurs, where Al3+ ions on the outer surface of the nanotubes are replaced by Fe3+ ions. In Fe-doped aluminosilicate nanotubes, isomorphic substitution of Al3+ by Fe3+ is found to affect the band gap of doped imogolite. Nonetheless, Fe3+ sites on the outer surface of nanotubes are able to coordinate organic moieties, like the azo-dye Acid Orange 7, through a ligand-displacement mechanism occurring in an aqueous solution.

Here, we present a protocol to synthesize and characterize Fe-doped aluminosilicate nanotubes. The materials are obtained by either sol-gel synthesis upon addition of FeCl3&#8226;6H2O to the mixture containing the Si and Al precursors or by post-synthesis ionic exchange of preformed aluminosilicate nanotubes.

향상된 전자 전도성 특성을 가진 철 - 도핑 된 알루미 노 실리케이트 나노 튜브의 합성 및 특성

The goal of the protocol is to synthesize Fe-doped aluminosilicate nanotubes of the imogolite type with the formula (OH)3Al2-xFexO3SiOH. Doping with Fe ...

Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be covalently and site-specifically linked via their end facets, resulting in polymer-like linear or branched chains. The linking procedure begins with a cation-exchange process in which the end facets of the cadmium chalcogenide NCs are first converted to silver chalcogenide. This is followed by the selective removal of ligands at their surface. This results in cadmium chalcogenide NCs with highly reactive silver chalcogenide end facets that spontaneously fuse upon contact with each other, thereby establishing an interparticle facet-to-facet attachment. Through the judicious choice of precursor concentrations, an extensive network of linked NCs can be produced. Structural characterization of the linked NCs is carried out via low- and high-resolution transmission electron microscopy (TEM), as well as energy-dispersive X-ray spectroscopy, which confirm the presence of silver chalcogenide domains between chains of cadmium chalcogenide NCs.

A protocol detailing how shape-anisotropic colloidal cadmium chalcogenide nanocrystals can be covalently linked via their end facets is presented here.

면 대 면 모양 이방성 콜 로이드 카드뮴 칼코게나이드 Nanostructures의 연결

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be ...

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the aziridine ring. The utility of bicyclic aziridinium ions, specifically 1-azoniabicyclo[3.1.0]hexane and 1-azoniabicyclo[4.1.0]heptane tosylate highlighted in the aziridine ring openings by the nucleophile with the release of the ring strain to yield the corresponding ring-expanded azaheterocycles such as pyrrolidine, piperidine and azepane with diverse substituents on the ring in regio- and stereospecific manner. Herein, we report a simple and convenient method for the preparation of the stable 1-azabicyclo[4.1.0]heptane tosylate followed by selective ring opening via a nucleophilic attack either at the bridge or at the bridgehead carbon to yield piperidine and azepane rings, respectively. This synthetic strategy allowed us to prepare biologically active natural products containing piperidine and azepane motif including sedamine, allosedamine, fagomine and balanol in highly efficient manner.

Bicyclic aziridinium ions such as 1-azoniabicyclo[4.1.0]heptane tosylate were generated from 2-[4-tolenesulfonyloxybutyl]aziridine, which was utilized for the preparation of substituted piperidines and azepanes via regio- and stereospecific ring-expansion with various nucleophiles. This highly efficient protocol allowed us to prepare diverse azaheterocycles including natural products such as fagomine, febrifugine analogue and balanol.

Azaheterocycles의 합성에 대 한 안정적인 Bicyclic Aziridinium 이온과 그들의 반지 개통 준비

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

활성 표면 성장 메커니즘을 통해 기판 바인딩된 Au 나노 와이어의 합성

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to diversify the fiber choices in the United States body armor market, copolymer fibers based on the combination of 5-amino-2-(p-aminophenyl) benzimidazole (PBIA) and the more conventional PPTA were introduced. Little is known regarding the long-term stability of these fibers, but as condensation polymers, they are expected to have potential sensitivity to moisture and humidity. Therefore, characterizing the strength of the materials and understanding their vulnerability to environmental conditions is important for evaluating their use lifetime in safety applications. Ballistic resistance and other critical structural properties of these fibers are predicated on their strength. To accurately determine the strength of the individual fibers, it is necessary to disentangle them from the yarn without introducing any damage. Three aramid-based copolymer fibers were selected for the study. The fibers were washed with acetone followed by methanol to remove an organic coating that held the individual fibers in each yarn bundle together. This coating makes it difficult to separate single fibers from the yarn bundle for mechanical testing without damaging the fibers and affecting their strength. After washing, fourier transform infrared (FTIR) spectroscopy was performed on both washed and unwashed samples and the results were compared. This experiment has shown that there are no significant variations in the spectra of poly(p-phenylene-benzimidazole-terephthalamide-co-p-phenylene terephthalamide) (PBIA-co-PPTA1) and PBIA-co-PPTA3 after washing, and only a small variation in intensity for PBIA. This indicates that the acetone and methanol rinses are not adversely affecting the fibers and causing chemical degradation. Additionally, single fiber tensile testing was performed on the washed fibers to characterize their initial tensile strength and strain to failure, and compare those to other reported values. Iterative procedural development was necessary to find a successful method for performing tensile testing on these fibers.

The primary goal of the study is to develop a protocol to prepare consistent specimens for accurate mechanical testing of high strength copolymer aramid fibers, by removing a coating and disentangling the individual fiber strands without introducing significant chemical or physical degradation.

그들의 기계적 특성의 결정 수 있도록 고 강도 공중 합체 Aramid 섬유 disentangling

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to ...

Synthesis of In37P20(O2CR)51 Clusters and Their Conversion to InP Quantum Dots

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 clusters have been observed as intermediates in the synthesis of InP quantum dots from molecular precursors (In(O2CR)3, HO2CR, and P(SiMe3)3) and may be isolated as a pure reagent for subsequent study and use as a single-source precursor. These clusters readily convert to crystalline and relatively monodisperse samples of quasi-spherical InP quantum dots when subjected to thermolysis conditions in the absence of additional precursors above 200 &#176;C. The optical properties, morphology, and structure of both the clusters and quantum dots are confirmed using UV-Vis spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, and powder X-ray diffraction. The molecular symmetry of the clusters is additionally confirmed by solution-phase 31P NMR spectroscopy. This protocol demonstrates the preparation and isolation of atomically-precise InP clusters, and their reliable and scalable conversion to InP QDs.

Synthesis of In37P20O2CR51 Clusters and Their Conversion to InP Quantum Dots

A protocol for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots is presented.

37P 20(o2CR)51 클러스터의 합성 및 InP 양자 점으로의 변환

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 ...

Design, Synthesis, and Photochemical Properties of Clickable Caged Compounds

Caged compounds enable the photo-mediated manipulation of the cell physiology with high spatiotemporal resolution. However, the limited structural diversity of currently available caging groups and the difficulties in synthetic modification without sacrificing their photolysis efficiencies are obstacles to expanding the repertoire of caged compounds for live cell applications. As the chemical modification of coumarin-type photo-caging groups is a promising approach for the preparation of caged compounds with diverse physical and chemical properties, we report a method for the synthesis of clickable caged compounds that can be modified easily with various functional units via the copper(I)-catalyzed Huisgen cyclization. The modular platform molecule contains a (6-bromo-7-hydroxycoumarin-4-yl)methyl (Bhc) group as a photo-caging group, which exhibits a high photolysis efficiency compared to those of the conventional 2-nitrobenzyls. General procedures for the preparation of clickable caged compounds containing amines, alcohols, and carboxylates are presented. Additional properties such as the water solubility and cell targeting ability can be readily incorporated into clickable caged compounds. Furthermore, the physical and photochemical properties, including the photolysis quantum yield, were measured and were found to be superior to those of the corresponding Bhc caged compounds. The described protocol could therefore be considered a potential solution for the lack of structural diversity in the available caged compounds.

A protocol for the synthesis and measurement of the photochemical properties of modular caged compounds with clickable moieties is presented.