## 2 Materials and Methods
### Analytical Methods  
\({}^{29}\)Si MAS NMR spectra were recorded using a DSX 400 Bruker spectrometer (Bruker, Billerica, MA, USA). Spectra were acquired in HPDec mode with a 4 \(\upmu\)s pulse at 90\({}^{\circ}\) and with a 100 s delay between pulses. \({}^{13}\)C MAS NMR, spectra were recorded using a DSX 400 Bruker spectrometer(Bruker, Billerica, MA, USA). Spectra were acquired in HPDec mode with a 5 \(\upmu\)s pulse at 90\({}^{\circ}\) and with a 100 s delay between pulses. Elemental analyzes of the preceramic siloxane microspheres for carbon and hydrogen content were performed using CHNS analyzer EuroVector model 3018 Elementar Analysensysteme (GmbH, Langenselbold, Germany). Elemental analyzes of ceramic microspheres for the determination of free carbon, C\({}_{t}\), were carried out in Lukasiewicz Research Network--Institute for Ferrous Metallurgy in Gliwice, Poland. C\({}_{t}\) was calculated from C\({}_{\text{total}}\) which was determined by the burning in oxygen of the studied sample mixed with PbCrO\({}_{4}\) and the formed CO\({}_{2}\) was analyzed in the Kulomat 702/SO/CS apparatus (Strolheim, Germany). Determination of the oxygen content in the ceramic microspheres was carried out using a gas analyzer model TCHEN-600 made by LECO Co.(LECO, St. Joseph, MI, USA) in Lukasiewicz Research Network--Institute for Ferrous Metallurgy in Gliwice, Poland. Scanning Electron Microscope images were taken with a Jeol JSH 5500 LV microscope (JEOL Ltd., Tokyo, Japan) in a high vacuum mode, at the accelerated voltage of 10 kV. Samples were coated with a fine gold layer (about 20 nm thick), using sputter coater JEOL JFC 1200 (JEOL Ltd., Tokyo, Japan). SEM-EDS spectra were recorded with the JEOL JSM-6010 LA (JEOL Ltd., Tokyo, Japan) scanning electron microscope operating at accelerating voltage of 15 kV, equipped with an energy-dispersive X-ray detector. The surfaces of the analyzed samples were sputtered with a fine gold layer (20 nm thick) before analysis. XRD diffractograms were obtained using a Panalytical X'Pert MPD PRO instrument (Malvern Panalytical, Egham, England) equipped with a roentgen lamp with copper anode, X'Celerator detector and Johansson monochromator. Measurements were carried out in the Bragg-Brentano geometry over a 20 range from 5\({}^{\circ}\) to 75\({}^{\circ}\) with a 0.008\({}^{\circ}\) step and a step time of 106 s.  
Raman spectra were recorded using a Raman HORIBA LabRAM HR micro spectrometer (HORIBA Laboratory, Kyoto, Japan) using an excitation beam at \(\lambda_{\mathrm{exc}}\) = 488.0 nm. TGA for analysis of free carbon content was performed by heating sample in air from 25 \({}^{\circ}\)C to 80 \({}^{\circ}\)C with rate of 5 \({}^{\circ}\)C/min and hold at 800 \({}^{\circ}\)C for 3 h using analyzer TGA 5500 (TA Instruments, New Castle, PA, USA). Mercury Injection Capillary Pressure (MICP) measurements were performed in specialized porosimetric laboratory at AGH University of Science and Technology in Cracow, Faculty of Geology, Geophysics and Ecology. An AutoPore IV 9500 mercury porosimeter from Micromeritics (Micromeritics Instrument Corporation, Norcross, GA, USA) was used. The test procedure was developed based on a standard test protocol ASTM-D4404-1 (the American Society for Testing and Materials, Pensylwania, USA, 2010), and the instruction manual for the AutoPore IV measuring apparatus (AutoPore IV 9520 Operator's Manual V1.09 2008). The Micrometrics ASAP 2020 Plus gas sorption analyzer(Micromeritics Instrument Corporation, Norcross, GA, USA) was used to study the surface and pore size distribution of the prepared materials. The samples were degassed at 573 K until the pressure stabilized at 5 \(\upmu\)mHg/min. Then, measurements of N\({}_{2}\) adsorption-desorption isotherms were performed at the temperature of 77.159 K. The area and pore size distribution were calculated with the MicroActive software (for Windows). BET multi-point analysis (Brunauer-Emmett-Teller) was used to calculate the total area.