title: Making flexible magnetic aerogels and stiff magnetic nanopaper using cellulose nanofibrils as templates.
abstract: Nanostructured biological materials inspire the creation of materials with tunable mechanical properties. Strong cellulose nanofibrils derived from bacteria or wood can form ductile or tough networks that are suitable as functional materials. Here, we show that freeze-dried bacterial cellulose nanofibril aerogels can be used as templates for making lightweight porous magnetic aerogels, which can be compacted into a stiff magnetic nanopaper. The 20-70-nm-thick cellulose nanofibrils act as templates for the non-agglomerated growth of ferromagnetic cobalt ferrite nanoparticles (diameter, 40-120 nm). Unlike solvent-swollen gels and ferrogels, our magnetic aerogel is dry, lightweight, porous (98%), flexible, and can be actuated by a small household magnet. Moreover, it can absorb water and release it upon compression. Owing to their flexibility, high porosity and surface area, these aerogels are expected to be useful in microfluidics devices and as electronic actuators.
authors.affiliation: Department of Fibre and Polymer Technology, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
authors.forename: R T
authors.initials: RT
authors.lastname: Olsson
authors.forename: M A S
authors.initials: MA
authors.lastname: Azizi Samir
authors.forename: G
authors.initials: G
authors.lastname: Salazar-Alvarez
authors.forename: L
authors.initials: L
authors.lastname: Belova
authors.forename: V
authors.initials: V
authors.lastname: Ström
authors.forename: L A
authors.initials: LA
authors.lastname: Berglund
authors.forename: O
authors.initials: O
authors.lastname: Ikkala
authors.forename: J
authors.initials: J
authors.lastname: Nogués
authors.forename: U W
authors.initials: UW
authors.lastname: Gedde
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D055119:Elastic Modulus; D004867:Equipment Design; D019544:Equipment Failure Analysis; D046911:Macromolecular Substances / Q000737:chemistry; D008280:Magnetics / Q000295:instrumentation*; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010209:Paper; D010316:Particle Size; D016062:Porosity; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D002482:Cellulose