Evaporation Caused Invaginations of Acoustically Levitated Colloidal Droplets
Controlled buckling of colloidal droplets via acoustic levitation plays an important role in pharmaceutical, coating, and material self-assembly. In this study, the evaporation process of PTFE colloidal droplets with two particle concentrations (60 wt% and 20 wt%) was investigated under acoustic lev...
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| Format: | Article |
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MDPI AG
2022-12-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/13/1/133 |
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| author | Hongyue Chen Yongjian Zhang Heyi Wang Xin Dong Duyang Zang |
| author_facet | Hongyue Chen Yongjian Zhang Heyi Wang Xin Dong Duyang Zang |
| author_sort | Hongyue Chen |
| collection | DOAJ |
| description | Controlled buckling of colloidal droplets via acoustic levitation plays an important role in pharmaceutical, coating, and material self-assembly. In this study, the evaporation process of PTFE colloidal droplets with two particle concentrations (60 wt% and 20 wt%) was investigated under acoustic levitation. We report the occurrence of surface invagination caused by evaporation. For the high particle concentration droplet, the upper surface was invaginated, eventually forming a bowl-shaped structure. While for the low particle concentration droplet, both the upper and lower surfaces of the droplet were invaginated, resulting in a doughnut-like structure. For the acoustically levitated oblate spherical droplet, the dispersant loss at the equatorial area of the droplet is greater than that at the two poles. Therefore, the thickness of the solid shell on the surface of the droplet was not uniform, resulting in invagination at the weaker pole area. Moreover, once the droplet surface was buckling, the hollow cavity on the droplet surface would absorb the sound energy and results in strong positive acoustic radiation pressure at bottom of the invagination, thus further prompting the invagination process. |
| first_indexed | 2024-03-09T09:43:35Z |
| format | Article |
| id | doaj.art-5e6bafc7ed794bb0a3cac8272ff17676 |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-09T09:43:35Z |
| publishDate | 2022-12-01 |
| publisher | MDPI AG |
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| series | Nanomaterials |
| spelling | doaj.art-5e6bafc7ed794bb0a3cac8272ff176762023-12-02T00:44:42ZengMDPI AGNanomaterials2079-49912022-12-0113113310.3390/nano13010133Evaporation Caused Invaginations of Acoustically Levitated Colloidal DropletsHongyue Chen0Yongjian Zhang1Heyi Wang2Xin Dong3Duyang Zang4MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, ChinaShaanxi Key Laboratory of Surface Engineering and Remanufacturing, School of Mechanical and Material Engineering, Xi’an University, Xi’an 710065, ChinaShaanxi Key Laboratory of Surface Engineering and Remanufacturing, School of Mechanical and Material Engineering, Xi’an University, Xi’an 710065, ChinaShaanxi Key Laboratory of Surface Engineering and Remanufacturing, School of Mechanical and Material Engineering, Xi’an University, Xi’an 710065, ChinaMOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, ChinaControlled buckling of colloidal droplets via acoustic levitation plays an important role in pharmaceutical, coating, and material self-assembly. In this study, the evaporation process of PTFE colloidal droplets with two particle concentrations (60 wt% and 20 wt%) was investigated under acoustic levitation. We report the occurrence of surface invagination caused by evaporation. For the high particle concentration droplet, the upper surface was invaginated, eventually forming a bowl-shaped structure. While for the low particle concentration droplet, both the upper and lower surfaces of the droplet were invaginated, resulting in a doughnut-like structure. For the acoustically levitated oblate spherical droplet, the dispersant loss at the equatorial area of the droplet is greater than that at the two poles. Therefore, the thickness of the solid shell on the surface of the droplet was not uniform, resulting in invagination at the weaker pole area. Moreover, once the droplet surface was buckling, the hollow cavity on the droplet surface would absorb the sound energy and results in strong positive acoustic radiation pressure at bottom of the invagination, thus further prompting the invagination process.https://www.mdpi.com/2079-4991/13/1/133colloidal droplet evaporationacoustic levitationevaporation fluxsurface invagination |
| spellingShingle | Hongyue Chen Yongjian Zhang Heyi Wang Xin Dong Duyang Zang Evaporation Caused Invaginations of Acoustically Levitated Colloidal Droplets Nanomaterials colloidal droplet evaporation acoustic levitation evaporation flux surface invagination |
| title | Evaporation Caused Invaginations of Acoustically Levitated Colloidal Droplets |
| title_full | Evaporation Caused Invaginations of Acoustically Levitated Colloidal Droplets |
| title_fullStr | Evaporation Caused Invaginations of Acoustically Levitated Colloidal Droplets |
| title_full_unstemmed | Evaporation Caused Invaginations of Acoustically Levitated Colloidal Droplets |
| title_short | Evaporation Caused Invaginations of Acoustically Levitated Colloidal Droplets |
| title_sort | evaporation caused invaginations of acoustically levitated colloidal droplets |
| topic | colloidal droplet evaporation acoustic levitation evaporation flux surface invagination |
| url | https://www.mdpi.com/2079-4991/13/1/133 |
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