Hierarchical porous SiOC-based ceramics developed from infiltration of poplar templates with a polisilsesquioxane

C. S. CERTUCHE ARENAS; M. A. CAMERUCCI; M. L. SANDOVAL

Darmstadt

Congreso; Materials Science Engineering, MSE 2018; 2018

German Material Society

The nature has become an innovation model for the design of porous ceramic structures. In particular, wood tissue is considered as a potential candidate to be used as template to generate different micro, meso and macro-cellular ceramic structures because it presents a hierarchical porous microstructure and unique microstructure-properties relationships. Several processing routes include in a variable sequential order the infiltration of a carbon template with different chemical agents and the subsequent pyrolysis in controlled atmosphere. However, an alternative processing route that has been little studied, which is based on the infiltration of wood templates with a silicon-based preceramic polymer and pyrolysis in non-oxidant atmosphere, is presented as a promising way for the development of porous biomimetic SiOC-based ceramics. In this work, a polysilsesquioxane (MP-POSS; silicon-based preceramic polymer) with high concentration of Si-OH groups was synthetized by hydrolytic condensation of 3-methacryloxypropyl-trimethoxysilane (molar ratio HCOOH/Si=0.055; 60°C, 1.5 days). This organic-inorganic hybrid compound, which was characterized by density measurement, ATR, 1H, 13C and 29Si liquid NMR, DSC and rheological testing in rotational and oscillatory conditions, was used as infiltration agent of poplar templates (native and physically activated by Soxhlet extraction using an specific sequence of solvents; diameter=2.0cm, length =1.5cm). These templates were characterized by density (Arquimedes method) and porosity measurements, and optical microscopy and SEM. The infiltration of the templates was carried out under vacuum and pressure (35 and 50 bar) at room temperature. All the infiltrated samples were cured in an electrical oven at 70 and 135°C, 3h and characterized by measurements of weight gain, density and porosity, and by ATG, mercury porosimetry, optical microscopy and SEM/EDS. The pyrolysis was performed at different temperatures (1000°C-1500°C) in N2 atmosphere, and the obtained porous biomimetic SiOC-based ceramics were characterized by XRD, SEM/EDS, FTIR, mercury porosimetry and Raman.