Flexible hybrid organic/inorganic SiOx aerogels via in situ template condensation
Time: Thu 2024-10-03 10.00
Location: F3 (Flodis), Lindstedtsvägen 26 & 28, Stockholm
Language: English
Subject area: Fibre and Polymer Science
Doctoral student: Björn K. Birdsong , Polymera material
Opponent: Dr Amparo Lopez-Rubio, Spanish National Research Council (CSIC), Spanien
Supervisor: Professor Richard Olsson, Polymera material; Professor Mikael S. Hedenqvist, Polymera material, Wallenberg Wood Science Center; Doktor Antonio Jose Capezza, Polymera material
QC 20240910
Embargo t.o.m. 2025-10-03 godkänt av skolchef Amelie Eriksson Karlström via e-post
Abstract
Modern insulation materials such as mineral wool are common but have known health risks. Cellulose-based insulation is an improvement regarding health but is flammable by itself and can settle. Aerogels are an attractive insulation material due to their incredible insulation while also very light, they are made from an abundant non-toxic material (silicon oxide). Several challenges need to be overcome to be viable for common use. Critical point drying is often used which is slow and has a high risk of failure. Further aerogels are brittle where even small deformations result in breaking, limiting their use.This work focused on using graphene oxide, mycelium, or cellulose as organic templates to make organic/inorganic hybrid aerogels by controlled silane condensation.Using graphene oxide (GO) showed that both APTES and TEOS were able to form uniform, smooth silane layers on an organic GO template. It was also possible to remove the GO template without changing the formed silicon oxide material using high temperature. With similar developed condensation conditions, it was possible to form SiOx coatings on bacterial cellulose nanofibrils (bCNF), the choice of silane allowed control over the formed coating morphology, and the modified bCNF dispersion could be freeze-dried into aerogels. To explore the developed coating methodology, another promising insulation material (mycelium) was used as a template. The mimicking of the mycelium hyphae was shown possible, enabling silicon oxide nanofibers after the removal of the mycelium template. Lastly, sol-gel formed organic/inorganic aerogels were developed, using bCNF as a toughening matrix, enabling high flexibility without crack formation or shattering even after significant deformation. The aerogels were thermally stable, flexibile, and avoided critical point drying allowing for large-scale aerogel production.