期刊
出版社
ROYAL SOC
DOI: 10.1098/rsta.2019.0254
关键词
rheometry; alginate; magnetic fluids or gels; magneto-polymer; shear thinning; particle clusters
资金
- UTE University of Ecuador
- Ministerio de Economia, Industria y Competitividad, MINECO
- Agencia Estatal de Investigacion, AEI, Spain
- Fondo Europeo de Desarrollo Regional, FEDER, European Union [FIS201785954-R]
- Ministry of Education and Science of the Russian Federation [FEUZ-20200051]
- Russian Fund of Basic Researches [19-52-12028]
Even in the absence of cross-linking, at large enough concentration, long polymer strands have a strong influence on the rheology of aqueous systems. In this work, we show that solutions of medium molecular weight (120 000-190 000 g mol(-1)) alginate polymer retained a liquid-like behaviour even for concentrations as large as 20% w/v. On the contrary, solutions of alginate polymer of larger (and also polydisperse) molecular weight (up to 600 000 g mol(-1)) presented a gel-like behaviour already at concentrations of 7% w/v. We dispersed micrometre-sized iron particles at a concentration of 5% v/v in these solutions, which resulted in either stable magnetic fluids or gels, depending on the type of alginate polymer employed (medium or large molecular weight, respectively). These magneto-polymer composites presented a shear-thinning behaviour that allowed injection through a syringe and recovery of the original properties afterwards. More interestingly, application of a magnetic field resulted in the formation of particle clusters elongated along the field direction. The presence of these clusters intensely affected the rheology of the systems, allowing a reversible control of their stiffness. We finally developed theoretical modelling for the prediction of the magnetic-sensitive rheological properties of these magneto-polymer colloids. This article is part of the theme issue 'Patterns in soft and biological matters'.
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