title: Centrifugation-assisted Assembly of Colloidal Silica into Crack-Free and Transferrable Films with Tunable Crystalline Structures.
abstract: Self-assembly of colloidal particles into colloidal films has many actual and potential applications. While various strategies have been developed to direct the assembly of colloidal particles, fabrication of crack-free and transferrable colloidal film with controllable crystal structures still remains a major challenge. Here we show a centrifugation-assisted assembly of colloidal silica spheres into free-standing colloidal film by using the liquid/liquid interfaces of three immiscible phases. Through independent control of centrifugal force and interparticle electrostatic repulsion, polycrystalline, single-crystalline and quasi-amorphous structures can be readily obtained. More importantly, by dehydration of silica particles during centrifugation, the spontaneous formation of capillary water bridges between particles enables the binding and pre-shrinkage of the assembled array at the fluid interface. Thus the assembled colloidal films are not only crack-free, but also robust and flexible enough to be easily transferred on various planar and curved substrates.
authors.affiliation: Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers, Advanced Coatings Research Center of Ministry of Education of China, Fudan University, Shanghai 200433, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Fan
authors.affiliation: Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers, Advanced Coatings Research Center of Ministry of Education of China, Fudan University, Shanghai 200433, China.
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104, USA.
authors.forename: Shu
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers, Advanced Coatings Research Center of Ministry of Education of China, Fudan University, Shanghai 200433, China.
authors.forename: Limin
authors.initials: L
authors.lastname: Wu