Preparation of magnesium oxide and magnesium silicate replicas retaining the hierarchical structure of pine wood

Replicas retaining the structural characteristics of softwood (Pinus sylvestris) were obtained by infiltrating pretreated templates with a methanolic methoxymagnesium methyl carbonate (MeOMgOCO₂Me) solution as a precursor which then hydrolyzed into MgCO₃ nanoparticles. Subsequent calcination at temperatures ranging from 500 to 1450°C yielded annealed MgO replicas on levels of hierarchy from the macroscopic to the submicron scale. The mechanical stability of the replicas could be improved through calcination at 1450°C. However, this treatment leads to considerable shrinkage (Δ_ax = 56%). Even more stable MgO replicas were obtained by infiltrating the pine template first with MeOMgOCO₂Me, followed by a second infiltration step with an ethanolic tetraethyl orthosilicate (TEOS) solution and subsequent calcination at 1350°C. The resulting replicas constitute an MgO framework overgrown with Mg₂SiO₄ (forsterite) and exhibit compression strengths of 31 ± 8 MPa, as well as hierarchical structures combined with an anisotropic porosity.