title: Thermally insulating and fire-retardant lightweight anisotropic foams based on nanocellulose and graphene oxide.
abstract: High-performance thermally insulating materials from renewable resources are needed to improve the energy efficiency of buildings. Traditional fossil-fuel-derived insulation materials such as expanded polystyrene and polyurethane have thermal conductivities that are too high for retrofitting or for building new, surface-efficient passive houses. Tailored materials such as aerogels and vacuum insulating panels are fragile and susceptible to perforation. Here, we show that freeze-casting suspensions of cellulose nanofibres, graphene oxide and sepiolite nanorods produces super-insulating, fire-retardant and strong anisotropic foams that perform better than traditional polymer-based insulating materials. The foams are ultralight, show excellent combustion resistance and exhibit a thermal conductivity of 15 mW m(-1) K(-1), which is about half that of expanded polystyrene. At 30 °C and 85% relative humidity, the foams retained more than half of their initial strength. Our results show that nanoscale engineering is a promising strategy for producing foams with excellent properties using cellulose and other renewable nanosized fibrous materials.
authors.affiliation: Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: Bernd
authors.initials: B
authors.lastname: Wicklein
authors.affiliation: Engineering Ceramics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia.
authors.forename: Andraž
authors.initials: A
authors.lastname: Kocjan
authors.affiliation: 1] Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm, Sweden [2] Wallenberg Wood Science Centre, Royal Institute of Technology, KTH, 100 44 Stockholm, Sweden.
authors.forename: German
authors.initials: G
authors.lastname: Salazar-Alvarez
authors.affiliation: Politecnico di Torino, Corso Duca degli Abruzzi, 24 10129 Torino, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Carosio
authors.affiliation: Politecnico di Torino, Corso Duca degli Abruzzi, 24 10129 Torino, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Camino
authors.affiliation: Max Planck Institute for Colloids and Interfaces, Potsdam-Golm Science Park, Am Mühlenberg 1, 14476 Potsdam, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Antonietti
authors.affiliation: Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: Lennart
authors.initials: L
authors.lastname: Bergström