Name: tio2-coated hollow glass microspheres with superhydrophobic and high ir-reflective properties synthesized by a soft-chemistry method
Uploaded: 2017-04-26T15:00:00.000+00:00
Duration: 7 min 37 s
Description: Watch this Scientific Journal Video about TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method at JoVE.com

이 논문에서 설명하는 작업은 CII-HK / PolyU 혁신 기금에서 교부금에 의해 지원되었다. 또한 지원은 선전 공작 계획 (KQTD2015071616442225)와 중국 정부 &quot;천 재능&quot;프로그램 (Y62HB31601)에 의해 제공되었다. 또한, 응용 생물학과 및 화학 기술 홍콩 폴리 테크닉 대학 및 지속 가능한 도시 개발을위한 홍콩 폴리 테크닉 대학 연구소 (RISUD)의 도움에 감사드립니다.

HGM 1. 전처리 <ol><li> 무수 알코올 200 mL를 500 mL의 비커에 HGM 장소; 깨지지 HGM의 저밀도는 알코올에 정지되게되지만 깨진 HGM의 밀도가 알코올보다 크므로,이 용액에 침전. 30 분 후, 추가 애플리케이션의 오븐에서 80 ℃에서 건조하고 깨끗한 숟가락을 사용하여 현탁 HGM 수집. </li></ol> MCHGM 2. 합성 <ol><li> 깨지지 HGM 5g을 에탄올 47.5 ㎖, 및 3 구 플라스크에 탈 이온수 250 mL로 놓는다. 20 분 (예비 혼합) 400 R / 분으로 혼합 모터를 사용하여 교반 하였다. </li><li> TBT 15g을, PFOTES 1 g을 200 ㎖의 비이커에 무수 알코올 30 mL를 섞는다. 정압 깔때기에 혼합물을 붓고. </li><li> 세 구 플라스크의 구멍 중 하나에 정압 깔때기를 삽입한다. 의 속도로 3 구 플라스크에 정압 깔때기에 포함 된 혼합물을 삭제정압 깔때기의 밸브를 조정함으로써 달성되는 7 개 당 1 방울들. 3 시간 동안 반응을 계속합니다. </li><li> 수열 반응기에 3 구 플라스크에서 혼합 붓는다. 6 시간 동안 180 ℃로 오븐에서 적합한 강철 슬리브 밀폐 반응기를 넣어. 참고 : 원자로가 적절한 커버이 있는지 확인하십시오. 이 피복 한 후, 강철 슬리브 내로 넣어 반응기. 슬리브는 커버로 밀봉한다. </li><li> 반응이 끝난 후, 큰 숟가락을 사용하여 수열 반응기에 현탁하고 샘플을 수집한다. 4 시간이 MCHGM을 수득하여 80 ℃에서 샘플을 건조. </li></ol> F-3의 합성 SCHGM <ol><li> 깨지지 HGM 5 g을, 무수 에탄올 475 ㎖, 및 3 구 플라스크에 탈 이온수 250 mL를 넣고. 20 분 (예비 혼합) 400 R / 분으로 혼합 모터를 사용하여 교반 하였다. PFOTES 1 g 및 200 ㎖의 비이커에 무수 에탄올 30 mL를 섞는다. PFOTES 절대 전자 이동일정한 압력 깔때기 thanol 혼합물. </li><li> 세 구 플라스크에 정압 깔때기를 삽입한다. 7 개 (S) 당 1 방울의 속도로 3 구 플라스크에 정압 깔때기에 포함 된 혼합물을 놓는다. 3 시간 동안 실행 반응을 보자. </li><li> 수열 반응기에 3 구 플라스크에서 혼합 옮긴다. 6 시간 동안 180 ℃로 오븐에 넣어 밀봉 반응기. 반응이 끝난 후, 큰 숟가락을 사용하여 수열 반응기에 현탁하고 샘플을 수집한다. F-SCHGM을 구하는 4 시간 동안 80 ℃에서 샘플을 건조. </li></ol> 티 - SCHGM 4. 합성 <ol><li> 깨지지 HGM 5 g을, 무수 에탄올 475 ㎖, 및 3 구 플라스크에 탈 이온수 250 mL로 놓는다. 20 분 (예비 혼합) 400 R / 분 교반 하였다. TBT 15 g 및 200 ㎖의 비이커에 무수 에탄올 30 mL를 섞는다. 정압 깔때기에 TBT과 무수 에탄올의 혼합물을 전송. </li><li> 상수-대가를 삽입확인 3 구 플라스크에 깔때기. 7 개 (S) 당 1 방울의 속도로 3 구 플라스크에 정압 깔때기에 혼합물을 놓는다. 3 시간 동안 실행 반응을 보자. </li><li> 수열 반응기에 3 구 플라스크에서 혼합 옮긴다. 6 시간 동안 180 ℃로 오븐에 넣어 밀봉 반응기. 반응이 끝난 후 수열 반응의 샘플을 수집한다. 티 - SCHGM을 구하는 4 시간 동안 80 ℃에서 샘플을 건조. </li></ol> 5. 요소 특성 분석 <ol><li> 모든 샘플에 대한 XRD 특성 분석을 실시한다. 구리 Kα 방사선 (λ = 0.15406 ㎚)과 10 ° 내지 80 ° 범위의 2θ로 매우 다양한 범용 X 선 회절 장치를 사용하여 데이터를 수집한다. </li><li> 주사 전자 현미경 (20), 금 샘플을 분무 후 21 개 이미지를 획득. SEM을 테스트하는 동안, EDS가 특정 영역에 실시하고 있습니다. </li><li> 측정합니다접촉각 접촉 각도 각도계 (22)를 사용하여; 물 드롭 볼륨은 10 μL해야합니다. </li><li> 표면의 경사 각도를 변경하여 전락 각을 측정한다 (23). 물 드롭 그냥 아래로 슬라이드 수있을 때까지의 각도를 최소화합니다. <ol><li> (: 26mm X 76mm X 2mm 크기) 유리 시트에 양면 테이프를 부착. 숟가락을 사용하여, 균일 테이프에 분말 (F-SCHGM 또는 MCHGM)를 배치했다. 분말 표면 (0.05 ㎖의 부피) 인젝터를 사용하여 물방울을 추가한다. </li><li> 접촉 각도 고니 오 미터의 모터 플랫폼에서 유리 시트를 넣습니다. 1 ° / s의 속도로 모터 플랫폼 기울고하여 유리판을 기울여. 물 드롭 슬라이드 시작할 때 모터를 중지; 경사각 슬라이딩 각도이다. </li></ol></li><li> 분광 광도계 (24)를 이용하여 반사 스펙트럼을 측정한다. 참고 : 파장이 450 나노 미터에서 2,550 나노 미터이다. </li><li> 모든 샘플의 열전도도를 측정열전도율 측정기 (25)를 사용. </li></ol>

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The authors have nothing to disclose.

이 원고에서, 프로토콜의 중요한 단계는 열수 과정이다. 이는 이산화 티탄의 형성, 최종 반사율 및 superhydrophobicity에 영향을 미친다. 온도 제어 및 반응 시간도 매우 중요하다. 반응 조건을 변경하는 경우, 최종 제품은 결함이 될 수있다. 이 방법은 하나의 단계에서 소수성이 높은 IR 반사 HGM을 합성하는 간단한 방법을 제공한다. 이전 연구에서, 소수성 및 반사율 특성은 분리 수단 (28), (29), (30)에 의해 달성 하였다. 따라서, 모두를 얻기 위해, 적어도 두 단계가 요구된다. 이 논문에서, 하나의 단계 방법은 주로 생산 효율을 향상시키는 제안된다. 이들 두 특성과 결합하여 또한, 상기 IR 반사 코팅은 오염으로부터 보호하고, 도포 성능이 장기간 유지 될 수있다. &lt;/ p&gt; 그러나, 대규모 합성의 관점에서 한계가있다. 이 방법은 이러한 목적을 위해 변경되어야한다. 그것은 큰 열수 반응기에 올 때, 열 및 물질 전달이 잘 정리해야합니다. 그것은 한 번에 초 소수성이 높은 IR 반사 HGM의 합성 할 수 있기 때문에 기존의 방법에 비해이 기술은 중요하다. 코팅은 적외선을 반사 핵심 요소입니다. 따라서, 깨끗한 표면을 유지하는 것이 매우 중요하다. 소수성 자정 속성, 코팅은 오염으로부터 보호 할 수 있으며, 수명을 연장 할 수있다. 두 단계가 하나의 단계, 제조시 소비되는 에너지가 감소하기 때문에 또한,도 감소된다. 이 논문에서 설명 제안 된 기술은 다양한 애플리케이션으로 단열 재료를 합성하는 좋은 방법이다. 초 소수성 Property는 같은 IR 반사와 같은 다른 특성과 결합되어있다. 따라서, 필요한 경우 소수성 합성 방법은 IR 흡수 물질 (31), 부식 방지 재료 (32) 또는 태양 전지 (33)와 같은 다른 기능 재료에 적용 할 수있다.

유리 중공 구체 (HGM)는 10 내지 100 μm의 크기 범위의 무기 재료이다. 그들은 이러한 우수한 분산액, 높은 흐름 성, 낮은 밀도, 우수한 단열성 1, 2, 3, 4 등의 많은 유용한 기능들을 보여준다. 때문에 중공 구조, HGM이 매우 낮은 열전도도 10,도 11이있다. 이러한 이유로, 그들은 우주 항공 등 공학 (5), 심해 탐사 6, 7, 수소 저장 8, 9, 그러나, 그들은 여전히 낮은 강도 등의 단점을 보여 포함한 많은 분야에서 적용됩니다. 또한, IR 등이 HGM을 통해 전송하고 뒤에 제목을 가열 할 수있다. 그 때문에즉 HGM에 표면 변형은 복사 열 전달을 감소하는 것이 필수적이다. 효과적인 방법은 코팅에 HGM 표면 상에 적외선 차단 물질이다. 반도체로서, 이산화 티탄은 광 촉매 (12, 13), 태양 광 발전, 센서 제조 14, 애플리케이션 환경 (15), 에너지 저장 장치 (16) 등의 여러 분야에서 사용되고있다. 또한, 또한, 가시광 및 적외선 밴드 17, 18, 19 저 방사율을 나타낸다. 따라서, 우리의 목적을 위해, 이산화 티탄으로 인해 상대적으로 낮은 가격과 높은 성능 현명한 선택이었다. 그러나, 코팅은 오염이 심각 이산화 티탄의 반사율에 영향을 미치는, 파울하기가 매우 쉽습니다. 반사율이 점차 줄여야합니다. 따라서, SELF 세척 코팅하여 오염으로부터 방지 코팅과 같은 코팅의 작업 시간을 연장하는 것이 필수적이다. 이 논문에서, 소프트 화학적 방법은 소수성 이산화 티탄 코팅 된 HGM 개발 하였다. 테트라 부틸 티타 네이트 (TBT) 및 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PFOTES)의 각각의 Ti 공급원 및 소수성 화제로서 선택되었다. 그들은 가수 분해와 HGM의 표면에 증착되었다. 그 후, 열수 처리 후, 아나타제 이산화 티탄은 HGM 표면에 형성되고, 소수성 성질이 남아 있었다. 비교를 위해, 단일 코팅 HGM (F-SCHGM) 및 이산화 티탄 코팅 된 단일 HGM (티 - SCHGM) PFOTES도 합성 하였다. 합성 방식은도 1에 도시되어있다.

<table><tbody><tr><td>HGM</td><td>Technical Institute of Physics and Chemistry, Chinese Academy of Science</td><td>N/A</td><td>N/A</td></tr><tr><td>TBT</td><td>Sigma-Aldrich</td><td>CAS#: 5593-70-4</td><td>Analytical grade</td></tr><tr><td>Ethyl Alcohol</td><td>Sigma-Aldrich</td><td>CAS#: 64-17-5</td><td>Analytical grade</td></tr><tr><td>PFOTES</td><td>Sigma-Aldrich</td><td>CAS#: 51851-37-7</td><td>98%</td></tr></tbody></table>

tio2-coated hollow glass microspheres with superhydrophobic and high ir-reflective properties synthesized by a soft-chemistry method

이 원고는 초 소수성이 높은 IR 반사 중공 유리 마이크로 스피어 (HGM)를 개발하는 소프트 화학 방법을 제안한다. 아나타제 이산화 티탄 및 소수성 화제는 하나의 단계에서 HGM 표면에 코팅 하였다. TBT와 PFOTES은 각각의 Ti 공급원 및 소수성 화제로서 선택되었다. 그들은 모두 HGM에 코팅하고, 열수 처리 한 후, TBT는 이산화 티탄을 아나타제하기 위해 설정되었다. 이러한 방식으로, PFOTES / 이산화 티탄은 HGM (MCHGM)가 코팅 된 제조 하였다. 비교를 위해, 단일 코팅 HGM (F-SCHGM) 및 이산화 티탄 코팅 된 단일 HGM (티 - SCHGM) PFOTES도 합성 하였다. HGM 표면상의 PFOTES 및 이산화 티탄 피막은 X 선 회절 (XRD), 주사 전자 현미경 (SEM) 및 에너지 분산 검출기 (EDS) 특성화를 통해 입증되었다. MCHGM은 141.2 접촉각으로, 더 높은 접촉 각도 (153 °) 그러나 F-SCHGM보다 낮은 미끄럼 각 (16 °)을 보였다6; 및 67 °의 각도를 슬라이딩. 또한, 양의 Ti-SCHGM 및 MCHGM 원래 HGM 및 F-SCHGM보다 약 5.8 % 더 높았다 유사한 IR 반사율 값을 표시. 또한 PFOTES 코팅 간신히 열전도율을 바꿨다. 따라서, F-SCHGM는 0.0479 W / (m · K)의 열전도율로 확실히 0.0475 W / (m · K)이었다 일본어 HGM 같았다. MCHGM와 티 - SCHGM도 비슷했다. 이들의 열전도율 값은 각각 0.0543 W / (m · K)와 0.0543 W / (m · K)이었다. 이산화 티탄 코팅 약간 열전도율이 증가하지만, 반사율의 증가와 함께, 전체 열 절연 특성을 향상시켰다. 적외선 반사 특성이 HGM 코팅에 의해 제공되기 때문에 코팅이 파울되면 마지막으로, 반사율은 감소한다. 따라서, 소수성 코팅으로 표면이 오염으로부터 보호되고, 그 수명도 연장된다.

단계 4.4에서의 테스트는 많은 기능과 샘플의 특성을 알 수있다. X- 선 회절 (그림 2) 아나타제 이산화 티탄의 형성을 반영한다. 주사 전자 현미경 (도 3) EDS (도 4)는 HGM 표면에 피복 된 이산화 티탄과 PFOTES 표시. 접촉각 (도 5)와 슬라이딩 각도 (도 6) 시험은 superhydrophobicity를 나타낸다. 이 VI-NIR 투과율 시험 (도 8)는 코팅의 열 전도성을 증가시키지 않는 것을 보여준다 (도 9) 이산화 티탄 피막의 반사 특성 및 열전 도성을 설명한다. 도 2에 도시 된 바와 같이, 4 개 개의 샘플은 XRD 테스트를 겪는다. 약 2θ = 23 °에서의 넓은 피크는 메인 인 비정질의 SiO2를 나타내는HGM의 구성 요소입니다. 이 피크 HGM의 존재를 보여 4 개 개의 샘플에서 검출한다. PFOTES 몇 분자의 두께로 코팅 만이기 때문에, 상기 XRD 신호를 변경하지 않는다. 따라서, 원래 HGM, F-SCHGM, 티 - SCHGM 및 MCHGM의 XRD 패턴은 거의 동일하다. 티 - SCHGM 및 MCHGM 대해, 넓은의 SiO2, 다른 피크의 피크 ((101), (004), (200), (105), (211), (213) 및 (204))이다 게다가 완벽하게 표준 이산화 티탄 (PDF 번호 89-4921)에 색인. 이 아나타제 이산화 티탄이 최종 제품으로 형성되어 있음을 반영한다. 주사 전자 현미경 이미지는도 3에 도시된다. 이러한 화상에 나타내는 바와 같이 PFOTES 코팅 몇 분자 두께이기 때문에, F-SCHGM 원래 HGM 표면에 아무런 차이가 없다. MCHGM와 티 - SCHGM의 경우, 표면에 코팅이 있다는 것을 매우 분명하다. EDS의 결과를도 4에 나타낸다. 그림 3의 분홍색 지역은 EDS에 의해 조사 하였다. 도 4a에 도시 된 바와 같이, 전용의 Si, O, 나트륨, 칼슘 및 검출 하였다. 도 4b에서, 이들 네 개의 요소 외에, F는 검출된다. 이것은 HGM 표면에 코팅 될 나타났다 PFOTES의 특성 원소이다. 도 4c에서는도 4a의 4 개 원소 이외에, TI는 이산화 티탄은 HGM에 코팅되는 것을 나타내는 검출 하였다. 도 4D에서,도 4c에 다섯 개 원소 외에, F는 또한 검출되었다. 이것은 모두 이산화 티탄과 PFOTES가 HGM 표면에 코팅되어 있음을 보여줍니다. 접촉각은 조사 하였다. 도 5에 도시 된 바와 같이, 원래 HGM (도 5a)의 접촉 각도, F-SCHGM (도 5b), 티 - SCHGM (도 5c) 및 MCHGM (도5D)이 각각 59 °, 141.2 °, 85 °, 153 °이다. PFOTES의 도움으로, F-SCHGM 및 MCHGM의 접촉 각도는 모두 큰 증가를 나타낸다. 그러나, 자신의 슬라이딩 각도 (도 6)은 다르다. F-SCHGM MCHGM과의 슬라이딩 각도는 각각 67 °와 16 °이다. 이는 HGM에 이산화 티탄에 의해 형성되는 특수 구조입니다. 이러한 특별한 구조는 표면 거칠기가 증가하므로 슬라이딩 각도도 변화한다. 도 7에 도시하는 캐시 - 습윤 박스터 모델 (26)은 상기 소수성 현상을 설명 할 수있다. 화학식 1은이 모델을 설명한다. 이 수식에서, θ C는 θ는 영의 접촉각이 27이고, f는, 고상 율이고, 겉보기 접촉각이다. 이산화 티탄의 도움으로 HGM면과 F 값 모두 거칠기는 증가한다. 따라서, 접촉 각도는 더 큰되었다. 이산화 티탄이 코팅은 HGM 표면에 기둥 구조를 형성하는 데 도움이. 따라서 물방울이 에어 매트에 의해지지되고, 슬라이딩 할 때의 저항은 작다. 따라서 MCHGM의 전락 각은 작아진다. COS θ C = F의 cos θ (1 - - F) (1) 26 반사율은 조사도 8에 도시 하였다. PFOTES 코팅 거의 반사율을 변화하기 때문에, 이들 4 개의 샘플의 두 그룹으로 나누었다. 첫번째는 일본어 HGM 및 F-SCHGM이고, 두 번째는 티 - SCHGM 및 MCHGM이다. 각 그룹에서 반사율의 데이터는 매우 유사하다. 그러나, 이산화 티탄의 도움으로, 반사율은 5 % 증가했다. 마지막으로, 상기 열에서의 행위와 이산화 티탄 피막의 영향ctivity 조사 하였다. 산화 티타늄이 코팅은 HGM의 벽 두께를 증가하기 때문에이 필수적이다. 따라서, 이산화 티탄의 열전도율이 코팅 HGM HGM보다 약간 높은 코팅 된. 그러나, 열전 도성 향상은 전체의 단열 특성이 약화되도록 명확하지 않을 것이다. PFOTES 거의 열전도율을 변경하기 때문에,도 9에 도시 된 바와 같이, 이산화 티탄 만이 파라미터의 향상에 기여 하였다. 그러나, 증가는 제한적이었다. 일본어 HGM, F-SCHGM, 티 - SCHGM 및 MCHGM의 열전도율은 / 0.0475 W / (m · K), 0.0479 W / (m · K), 0.0546 W / (m · K), 및 0.0543 W이었다 각각 (m · K). 따라서, 이산화 티탄 코팅 인해 HGM 벽 두께의 증가로 열전도율이 증가하더라도, 약간의 증가가 있었다. 이러한 이산화 티탄의 전체 단열성이 HGM은 DERI 반사율 향상에 의해 개선 된 코팅 된산화 티타늄 2에서 VED. <img alt="그림 1" src="/files/ftp_upload/55389/55389fig1.jpg" /> 그림 1 : MCHGM의 합성 방식. 이러한 F-SCHGM 및 Ti-SCHGM 다른 시료의 경우, 프로세스가 매우 유사하지만, 관련 원료 않고있다. <a href="http://ecsource.jove.com/files/ftp_upload/55389/55389fig1large.jpg" target="_blank">이 그림의 더 큰 버전을 보려면 여기를 클릭하십시오.</a> <img alt="그림 2" src="/files/ftp_upload/55389/55389fig2.jpg" /> 그림 2 : 원래 HGM, 초 소수성의 TiO2 / HGM, 표준 아나타제 이산화 티탄의 XRD 스펙트럼. 스펙트럼은 구리 Kα 방사선 (λ = 0.15406 ㎚)과 10 ° 내지 80 ° 범위의 2θ로 매우 다양한 범용 X 선 회절 장치에 의해 검출 하였다. 원래 HGM 사이에는 분명한 차이가 없습니다F-SCHGM 또는 티 - SCHGM 및 MCHGM합니다. <a href="http://ecsource.jove.com/files/ftp_upload/55389/55389fig2large.jpg" target="_blank">이 그림의 더 큰 버전을 보려면 여기를 클릭하십시오.</a> <img alt="그림 3" src="/files/ftp_upload/55389/55389fig3.jpg" /> 도 3 (a) 원래 HGM의 형태, (b) F-SCHGM, (c) 티타늄 - SCHGM 및 주 사형 전자 현미경을 이용하여 검출 (d) MCHGM. 일본어 HGM 및 F-SCHGM 표면에 상기 코팅은 SEM을 통해 관찰 할 수 있지만, 코팅의 Ti-SCHGM 및 MCHGM의 표면에 존재한다. <a href="http://ecsource.jove.com/files/ftp_upload/55389/55389fig3large.jpg" target="_blank">이 그림의 더 큰 버전을 보려면 여기를 클릭하십시오.</a> <img alt="그림 4" src="/files/ftp_upload/55389/55389fig4.jpg" /> 도 4 (a) 원래의 적색 HG 액자 영역의 EDS 측정M, (b) F-SCHGM, (c) 티타늄 - SCHGM, 및 (d) MCHGM은, 주 사형 전자 현미경을 이용하여 검출. PFOTES과 이산화 티탄의 특징 요소를 검출 하였다. <img alt="그림 5" src="/files/ftp_upload/55389/55389fig5.jpg" /> 도 5 (a) 원래 HGM 접촉각, (b) F-SCHGM, (c) 티타늄 - SCHGM, 및 (d) 상기 접촉 MCHGM 광각 고니 오 미터로 검출된다. PFOTES의 도움으로, F-SCHGEM 및 MCHGM의 접촉 각도 값은 큰 증가를 보여줍니다. <a href="http://ecsource.jove.com/files/ftp_upload/55389/55389fig5large.jpg" target="_blank">이 그림의 더 큰 버전을 보려면 여기를 클릭하십시오.</a> <img alt="그림 6" src="/files/ftp_upload/55389/55389fig6.jpg" /> 도 6 (a) F-SCHGM 및 (b) MCHGM의 슬라이딩 각도. 빨간 원은 물방울의 슬라이딩 경로를 표시한다. MCHGM는 로우를 보여줍니다각 슬라이딩 r에. <a href="http://ecsource.jove.com/files/ftp_upload/55389/55389fig6large.jpg" target="_blank">이 그림의 더 큰 버전을 보려면 여기를 클릭하십시오.</a> <img alt="그림 7" src="/files/ftp_upload/55389/55389fig7.jpg" /> 그림 7 : superhydrophobicity의 이론을 젖음 캐시 - 박스터. 이 이론을 적시 설명하는 모델이다. 검은 원은 물 방울을 나타냅니다. 작은 기둥은 거친 표면을 나타냅니다. <img alt="그림 8" src="/files/ftp_upload/55389/55389fig8.jpg" /> 도 8 : 분광 광도계에 의해 검출 된 원래 HGM, F-SCHGM, 티 - SCHGM 및 MCHGM의 반사율 스펙트럼. 이산화 티탄은 HGM은 원래 HGM보다 반사율을 보여줍니다 - 코팅. <a href="http://ecsource.jove.com/files/ftp_upload/55389/55389fig8large.jpg" target="_blank">vi를하려면 여기를 클릭하십시오</a>이 그림의 더 큰 버전을 EW. <img alt="그림 9" src="/files/ftp_upload/55389/55389fig9.jpg" /> 도 9 : 열전도율 측정기에 의해 검출 된 4 개 개의 샘플의 열전도율. 열 전도성의 증가는 벽 두께의 증가로 유도한다. <a href="http://ecsource.jove.com/files/ftp_upload/55389/55389fig9large.jpg" target="_blank">이 그림의 더 큰 버전을 보려면 여기를 클릭하십시오.</a>

Watch this Scientific Journal Video about TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method at JoVE.com

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

This manuscript proposes a soft-chemistry method to synthesize superhydrophobic, TiO2-coated hollow glass microspheres (HGM) with high IR-reflective properties.

산화 티타늄<sub&gt; 2</sub소프트 - 화학 방법에 의해 합성 초 소수성 및 높은 IR 반사 특성과&gt; 코팅 된 투명 유리 마이크로 스피어

This manuscript proposes a soft-chemistry method to develop superhydrophobic and highly IR-reflective hollow glass microspheres (HGM). The anatase TiO2 ...

tio2-coated-hollow-glass-microspheres-with-superhydrophobic-high-ir

Nanyang Technological University

Research

JoVE Journal

Chemistry

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

10.0K 조회수.  City University of Hong Kong. This manuscript proposes a soft-chemistry method to synthesize superhydrophobic, TiO2-coated hollow glass microspheres (HGM) with high IR-reflective properties.

비디오: TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

Fabrication of Silica Ultra High Quality Factor Microresonators

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the quality factor (Q) of the cavity, can be in excess of 500ns for cavities with Q factors above 100 million. As a result of their low material losses, silica microcavities have demonstrated some of the longest photon lifetimes to date1-2. Since a portion of the circulating light extends outside the resonator, these devices can also be used to probe the surroundings. This interaction has enabled numerous experiments in biology, such as single molecule biodetection and antibody-antigen kinetics, as well as discoveries in other fields, such as development of ultra-low-threshold microlasers, characterization of thin films, and cavity quantum electrodynamics studies.3-7
The two primary silica resonant cavity geometries are the microsphere and the microtoroid. Both devices rely on a carbon dioxide laser reflow step to achieve their ultra-high-Q factors (Q&gt;100 million).1-2,8-9 However, there are several notable differences between the two structures. Silica microspheres are free-standing, supported by a single optical fiber, whereas silica microtoroids can be fabricated on a silicon wafer in large arrays using a combination of lithography and etching steps. These differences influence which device is optimal for a given experiment.
Here, we present detailed fabrication protocols for both types of resonant cavities. While the fabrication of microsphere resonant cavities is fairly straightforward, the fabrication of microtoroid resonant cavities requires additional specialized equipment and facilities (cleanroom). Therefore, this additional requirement may also influence which device is selected for a given experiment.
Introduction
An optical resonator efficiently confines light at specific wavelengths, known as the resonant wavelengths of the device. 1-2 The common figure of merit for these optical resonators is the quality factor or Q. This term describes the photon lifetime (&tau;o) within the resonator, which is directly related to the resonator's optical losses. Therefore, an optical resonator with a high Q factor has low optical losses, long photon lifetimes, and very low photon decay rates (1/&tau;o). As a result of the long photon lifetimes, it is possible to build-up extremely large circulating optical field intensities in these devices. This very unique property has allowed these devices to be used as laser sources and integrated biosensors.10
A unique sub-class of resonators is the whispering gallery mode optical microcavity. In these devices, the light is confined in circular orbits at the periphery. Therefore, the field is not completely confined within the device, but evanesces into the environment. Whispering gallery mode optical cavities have demonstrated some of the highest quality factors of any optical resonant cavity to date.9,11 Therefore, these devices are used throughout science and engineering, including in fundamental physics studies and in telecommunications as well as in biodetection experiments. 3-7,12
Optical microcavities can be fabricated from a wide range of materials and in a wide variety of geometries. A few examples include silica and silicon microtoroids, silicon, silicon nitride, and silica microdisks, micropillars, and silica and polymer microrings.13-17 The range in quality factor (Q) varies as dramatically as the geometry. Although both geometry and high Q are important considerations in any field, in many applications, there is far greater leverage in boosting device performance through Q enhancement. Among the numerous options detailed previously, the silica microsphere and the silica microtoroid resonator have achieved some of the highest Q factors to date.1,9 Additionally, as a result of the extremely low optical loss of silica from the visible through the near-IR, both microspheres and microtoroids are able to maintain their Q factors over a wide range of testing wavelengths.18 Finally, because silica is inherently biocompatible, it is routinely used in biodetection experiments.
In addition to high material absorption, there are several other potential loss mechanisms, including surface roughness, radiation loss, and contamination loss.2 Through an optimization of the device size, it is possible to eliminate radiation losses, which arise from poor optical field confinement within the device. Similarly, by storing a device in an appropriately clean environment, contamination of the surface can be minimized. Therefore, in addition to material loss, surface scattering is the primary loss mechanism of concern.2,8
In silica devices, surface scattering is minimized by using a laser reflow technique, which melts the silica through surface tension induced reflow. While spherical optical resonators have been studied for many years, it is only with recent advances in fabrication technologies that researchers been able to fabricate high quality silica optical toroidal microresonators (Q&gt;100 million) on a silicon substrate, thus paving the way for integration with microfluidics.1
The present series of protocols details how to fabricate both silica microsphere and microtoroid resonant cavities. While silica microsphere resonant cavities are well-established, microtoroid resonant cavities were only recently invented.1 As many of the fundamental methods used to fabricate the microsphere are also used in the more complex microtoroid fabrication procedure, by including both in a single protocol it will enable researchers to more easily trouble-shoot their experiments.

We describe the use of a carbon dioxide laser reflow technique to fabricate silica resonant cavities, including free-standing microspheres and on-chip microtoroids. The reflow method removes surface imperfections, allowing long photon lifetimes within both devices. The resulting devices have ultra high quality factors, enabling applications ranging from telecommunications to biodetection.

실리카 초고 품질 팩터 Microresonators의 제작

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the ...

연구

공학

Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials offering a superior control over the spatial distribution of charge carriers across material interfaces. As this study demonstrates, a combination of donor-acceptor nanocrystal (NC) domains in a single nanoparticle can lead to the realization of efficient photocatalytic1-5 materials, while a layered assembly of donor- and acceptor-like nanocrystals films gives rise to photovoltaic materials.
Initially the paper focuses on the synthesis of composite inorganic nanocrystals, comprising linearly stacked ZnSe, CdS, and Pt domains, which jointly promote photoinduced charge separation. These structures are used in aqueous solutions for the photocatalysis of water under solar radiation, resulting in the production of H2 gas. To enhance the photoinduced separation of charges, a nanorod morphology with a linear gradient originating from an intrinsic electric field is used5. The inter-domain energetics are then optimized to drive photogenerated electrons toward the Pt catalytic site while expelling the holes to the surface of ZnSe domains for sacrificial regeneration (via methanol). Here we show that the only efficient way to produce hydrogen is to use electron-donating ligands to passivate the surface states by tuning the energy level alignment at the semiconductor-ligand interface. Stable and efficient reduction of water is allowed by these ligands due to the fact that they fill vacancies in the valence band of the semiconductor domain, preventing energetic holes from degrading it. Specifically, we show that the energy of the hole is transferred to the ligand moiety, leaving the semiconductor domain functional. This enables us to return the entire nanocrystal-ligand system to a functional state, when the ligands are degraded, by simply adding fresh ligands to the system4.
To promote a photovoltaic charge separation, we use a composite two-layer solid of PbS and TiO2 films. In this configuration, photoinduced electrons are injected into TiO2 and are subsequently picked up by an FTO electrode, while holes are channeled to a Au electrode via PbS layer6. To develop the latter we introduce a Semiconductor Matrix Encapsulated Nanocrystal Arrays (SMENA) strategy, which allows bonding PbS NCs into the surrounding matrix of CdS semiconductor. As a result, fabricated solids exhibit excellent thermal stability, attributed to the heteroepitaxial structure of nanocrystal-matrix interfaces, and show compelling light-harvesting performance in prototype solar cells7.

A general strategy for the development of charge-separating semiconductor nanocrystal composites deployable for solar energy production is presented. We show that assembly of donor-acceptor nanocrystal domains in a single nanoparticle geometry gives rise to a photocatalytic function, while bulk-heterojunctions of donor-acceptor nanocrystal films can be used for photovoltaic energy conversion.

충전 분리 Nanocrystals와 고체를 통해 태양 에너지를 수확

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials ...

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 ...

화학

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

광 공진기 및 레이저 응용을위한 고분자 미소 구의 제조

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Synthesizing Sodium Tungstate and Sodium Molybdate Microcapsules via Bacterial Mineral Excretion

We present a method, the bacterial mineral excretion (BME), for synthesizing two kinds of microcapsules, sodium tungstate and sodium molybdate, and the two metal oxides&#39; corresponding nanoparticles&#8212;the former being as small as 22 nm and the latter 15 nm. We fed two strains of bacteria, Shewanella algae and Pandoraea sp., with various concentrations of tungstate or molybdate ions. The concentrations of tungstate and molybdate were adjusted to make microcapsules of different length-to-diameter ratios. We found that the higher the concentration the smaller the nanoparticles were. The nanoparticles came in with three length-to-diameter ratios: 10:1, 3:1 and 1:1, which were achieved by feeding the bacteria respectively with a low concentration, a medium concentration, and a high concentration. The images of the hollow microcapsules were taken via the scanning electron microsphere (SEM). Their crystal structures were verified by X-ray diffraction (XRD)&#8212;the crystal structure of molybdate microcapsules is Na2MoO4 and that of tungstate microcapsules is Na2WO4 with Na2W2O7. These syntheses all were accomplished under a near ambient condition.

This work presents a protocol for manufacture sodium tungstate and sodium molybdate microcapsules via bacteria and their corresponding nanoparticles.

나트륨 Tungstate 및 세균성 미네랄 배설을 통해 나트륨 몰 리브 덴 Microcapsules 합성

We present a method, the bacterial mineral excretion (BME), for synthesizing two kinds of microcapsules, sodium tungstate and sodium molybdate, and the ...

Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in industry. The wettability of the produced surface was analyzed by bouncing drop experiments and the topography was analyzed by confocal microscopy. In addition, we show various methodologies to measure its durability and anti-icing properties. Superhydrophobic surfaces hold a special texture that must be preserved to keep their water-repellency. To fabricate durable surfaces, we followed two strategies to incorporate a resistant texture. The first strategy is a direct incorporation of roughness to the metal substrate by acid etching. After this surface texturization, the surface energy was decreased by silanization or fluoropolymer deposition. The second strategy is the growth of a ceria layer (after surface texturization) that should enhance the surface hardness and corrosion resistance. The surface energy was decreased with a stearic acid film.
The durability of the superhydrophobic surfaces was examined by a particle impact test, mechanical wear by lateral abrasion, and UV-ozone resistance. The anti-icing properties were explored by studying the ability to repeal subcooled water, freezing delay, and ice adhesion.

We illustrate several methodologies to produce superhydrophobic metal surfaces and to explore their durability and anti-icing properties.

반 장식 응용 프로그램 Superhydrophobic 금속 표면의 제조

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in ...

Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis

Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe a novel protocol employing the TiO2 photocatalysis to locally alter cell affinity of the substrate surface. For this experiment, a thin TiO2 film was sputter-coated on a glass coverslip, and the TiO2 surface was subsequently modified with an organosilane monolayer derived from octadecyltrichlorosilane (OTS), which inhibits cell adhesion. The sample was immersed in a cell culture medium, and focused UV light was irradiated to an octagonal region. When a neuronal cell line PC12 cells were plated on the sample, cells adhered only on the UV-irradiated area. We further show that this surface modification can also be performed in situ, i.e., even when cells are growing on the substrate. Proper modification of the surface required an extracellular matrix protein collagen to be present in the medium at the time of UV irradiation. The technique presented here can potentially be employed in patterning multiple cell types for constructing coculture systems or to arbitrarily manipulate cells under culture.

Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis

We describe a protocol for modifying cell affinity of a scaffold surface in aqueous environment. The method takes advantage of titanium dioxide photocatalysis to decompose organic film in the photo-irradiated region. We show that it can be used to create microdomains of scaffolding proteins, both ex situ and in situ.

산화 티타늄을 사용하여 수성 환경에서 단백질과 세포를 포토 패터닝<sub&gt; 2</sub&gt; 광촉매

Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe ...

생체공학

A Facile Synthetic Method to Obtain Bismuth Oxyiodide Microspheres Highly Functional for the Photocatalytic Processes of Water Depuration

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of materials is highly related to its photocatalytic performance, it is necessary to standardize the synthetic methods in order to obtain the most functional architectures and, thus, the highest photocatalytic efficiency. Here, we report a reliable route to obtain BiOI microspheres via the solvothermal process, using Bi(NO3)3 and potassium iodide (KI) as precursors, and ethylene glycol as a template. The synthesis is standardized in a 150 mL autoclave, at 126 &#176;C for 18 h. This results in 2-3 &#181;m-sized mesoporous microspheres, with a relevant specific surface area (61.3 m2/g). Shortening the reaction times in the synthesis results in amorphous structures, while higher temperatures lead to a slight increase in the porosity of the microspheres, with no effect in the photocatalytic performance. The materials are photo-active under UV-A/visible light irradiation for the degradation of the antibiotic ciprofloxacin in water. This method has demonstrated to be effective in interlaboratory tests, obtaining similar BiOI microspheres in Mexican and Chilean research groups.

This article describes a synthetic method to obtain bismuth oxyiodide microspheres, which are highly functional to perform the photocatalytic removal of organic pollutants, such as ciprofloxacin, in water under UV-A/visible light irradiation.

물 Depuration의 촉매 프로세스에 대 한 매우 기능적 비스무트 Oxyiodide 스피어를 손쉬운 합성 방법

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of ...

Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars

We present microfabrication protocols for rendering intrinsically wetting materials repellent to liquids (omniphobic) by creating gas-entrapping microtextures (GEMs) on them comprising cavities and pillars with reentrant and doubly reentrant features. Specifically, we use SiO2/Si as the model system and share protocols for two-dimensional (2D) designing, photolithography, isotropic/anisotropic etching techniques, thermal oxide growth, piranha cleaning, and storage towards achieving those microtextures. Even though the conventional wisdom indicates that roughening intrinsically wetting surfaces (&#952;o &#60; 90&#176;) renders them even more wetting (&#952;r &#60; &#952;o &#60; 90&#176;), GEMs demonstrate liquid repellence despite the intrinsic wettability of the substrate. For instance, despite the intrinsic wettability of silica &#952;o &#8776; 40&#176; for the water/air system, and &#952;o &#8776; 20&#176; for the hexadecane/air system, GEMs comprising cavities entrap air robustly on immersion in those liquids, and the apparent contact angles for the droplets are &#952;r &#62; 90&#176;. The reentrant and doubly reentrant features in the GEMs stabilize the intruding liquid meniscus thereby trapping the liquid-solid-vapor system in metastable air-filled states (Cassie states) and delaying wetting transitions to the thermodynamically-stable fully-filled state (Wenzel state) by, for instance, hours to months. Similarly, SiO2/Si surfaces with arrays of reentrant and doubly reentrant micropillars demonstrate extremely high contact angles (&#952;r &#8776; 150&#176;&#8211;160&#176;) and low contact angle hysteresis for the probe liquids, thus characterized as superomniphobic. However, on immersion in the same liquids, those surfaces dramatically lose their superomniphobicity and get fully-filled within &#60;1 s. To address this challenge, we present protocols for hybrid designs that comprise arrays of doubly reentrant pillars surrounded by walls with doubly reentrant profiles. Indeed, hybrid microtextures entrap air on immersion in the probe liquids. To summarize, the protocols described here should enable the investigation of GEMs in the context of achieving omniphobicity without chemical coatings, such as perfluorocarbons, which might unlock the scope of inexpensive common materials for applications as omniphobic materials. Silica microtextures could also serve as templates for soft materials.

Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars

This work presents microfabrication protocols for achieving cavities and pillars with reentrant and doubly reentrant profiles on SiO2/Si wafers using photolithography and dry etching. Resulting microtextured surfaces demonstrate remarkable liquid repellence, characterized by robust long-term entrapment of air under wetting liquids, despite the intrinsic wettability of silica.

렌더링 SiO2/Si 표면 재진입 및 이중 재진입 구멍 또는 기둥을 포함하는 가스 를 포함하는 미세 질감을 조각하여 전지성

We present microfabrication protocols for rendering intrinsically wetting materials repellent to liquids (omniphobic) by creating gas-entrapping ...

Microhoneycomb Monoliths Prepared by the Unidirectional Freeze-drying of Cellulose Nanofiber Based Sols: Method and Extensions

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb monoliths (MHMs) with micrometer-scale channels are expected as efficient platforms for reactions and separations because of their large surface areas. Up to now, MHMs have been prepared by a unidirectional freeze-drying (UDF) method only from very limited precursors. Herein, we report a protocol from which a series of MHMs consisting of different components can be obtained. Recently, we found that cellulose nanofibers function as a distinct structure-directing agent towards the formation of MHMs through the UDF process. By mixing the cellulose nanofibers with water soluble substances which do not yield MHMs, a variety of composite MHMs can be prepared. This significantly enriches the chemical constitution of MHMs towards versatile applications.

Here, we present a general protocol to prepare a variety of microhoneycomb monoliths (MHMs) in which fluid can pass through with an extremely low pressure drop. MHMs obtained are expected to be used as filters, catalyst supports, flow-type electrodes, sensors and scaffolds for biomaterials.

셀 루 로스 Nanofiber 단방향 동결에 의해 준비 Microhoneycomb Monoliths 기반 Sols: 메서드 및 확장

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb ...

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