Particles at Oil鈥揂ir Surfaces: Powdered Oil, Liquid Oil Marbles, and Oil Foam

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• 作者：Bernard P. Binks ; Shaun K. Johnston ; Tomoko Sekine ; Andrew T. Tyowua
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：July 8, 2015
• 年：2015
• 卷：7
• 期：26
• 页码：14328-14337
• 全文大小：589K
• ISSN：1944-8252

文摘

The type of material stabilized by four kinds of fluorinated particles (sericite and bentonite platelet clays and spherical zinc oxide) in air鈥搊il mixtures has been investigated. It depends on the particle wettability and the degree of shear. Upon vigorous agitation, oil dispersions are formed in all the oils containing relatively large bentonite particles and in oils of relatively low surface tension (纬_la < 26 mN mp>鈥?p>) like dodecane, 20 cS silicone, and cyclomethicone containing the other fluorinated particles. Particle-stabilized oil foams were obtained in oils having 纬_la > 26 mN mp>鈥?p> where the advancing air鈥搊il鈥搒olid contact angle 胃 lies between ca. 90掳 and 120掳. Gentle shaking, however, gives oil-in-air liquid marbles with all the oil鈥損article systems except for cases where 胃 is <60掳. For oils of tension >24 mN mp>鈥?p> with omniphobic zinc oxide and sericite particles for which advancing 胃 鈮?90掳, dry oil powders consisting of oil drops in air which do not leak oil could be made upon gentle agitation up to a critical oil:particle ratio (COPR). Above the COPR, catastrophic phase inversion of the dry oil powders to air-in-oil foams was observed. When sheared on a substrate, the dry oil powders containing at least 60 wt % of oil release the encapsulated oil, making these materials attractive formulations in the cosmetic and food industries.