resumo
Ferrofluids and dry magnetic particles are two separate classes of magnetic materials with specific niche applications, mainly due to their distinct viscosity and interparticle distances. For practical applications, the stability of these two properties is highly desirable but hard to achieve. Conceptually, a possible solution to this problem would be encapsulating the magnetic particles but keeping them free to rotate inside a capsule with constant interparticle distances and thus shielded from changes in the viscosity of the surrounding media. Here we present an example of such materials by the encapsulation of magnetic ferrofluids into highly hydrophobic silica, leading to the formation of dry ferrofluids, i.e., a material behaving macroscopically as a dry powder but locally as a ferrofluid where magnetic nanoparticles are free to rotate in the liquid.
palavras-chave
WATER; NANOPARTICLES; EMULSIONS; PARTICLES; FOAMS
categoria
Chemistry; Science & Technology - Other Topics; Materials Science; Physics
autores
Sousa, FL; Bustamante, R; Millan, A; Palacio, F; Trindade, T; Silva, NJO
nossos autores
Filipa Lourosa Sousa
Investigador Júnior
Nuno João Silva
Investigador Principal
Tito Trindade
Professor Catedráticoagradecimentos
The authors acknowledge Dr Paul Wiper for reading the manuscript. Hydrophobic silica was kindly supplied by Evonik Degussa International AG. We acknowledge Fundacao para a Ciencia e Tecnologia (FCT, Portugal), COMPETE and FEDER programs (Pest-C/CTM/LA0011/2011) and the Portuguese National NMR Network (RNRMN). The Aveiro-Zaragoza collaboration has been supported by the Integrated Spanish-Portuguese Action PT2009-0131. The work in Zaragoza has been supported by the research grants MAT2011-27233-C02-02, MAT2011-25991 and CONSOLIDER CSD2007-00010 from the Ministry of Education. The financial support of the CSIC and Spanish Ministerio de Ciencia e Innovacion (PI201060E013) is also acknowledged. FLS and NJOS acknowledge FCT for SFRH/BPD/71033/2010 and Ciencia 2008 program, respectively.