<p> Supplementary Material</p><p>Facile Synthesis of SiO2 From Poly(silyne-co-carbyne) Preceramic Precursor</p><p>*Yusuf Nur, Gizem Bayol Mustafa Kemal University, Department of Chemistry, Antakya, Turkey. e-mail:</p><p> [email protected]</p><p>*Corresponding author: Dr. Yusuf Nur. Mustafa Kemal University, Department of Chemistry, </p><p>31060 Antakya, Turkey</p><p>Synthesis and Characterization of Poly(silyne-co-hydridocarbyne)</p><p>PSC was synthesized and characterized as reported in ref 13. Shortly, PSC was synthesized electrochemical in 50 ml of an undivided cell. A 1 ml of trichloro(dichloro methyl) silane (TCS) monomer (0.007 M, in 30 ml dimethoxy ethane (DME)) and 100 mg of tetrabutylammonium tetrafluoroborate (0.01 M, in 30 ml DME) was mixed in 30 ml of DME to prepare electrolyte solution while it was purged with argon gas. The cell was equipped with a 430 stainless steel (SS) as the cathode (5 cm × 2.5 cm × 0.5 mm) and copper (Cu) as the anode (5 cm × 2.5 cm × 0.5 mm. −8.0 V potential was applied to accomplish the electrolysis for 8 h at room temperature and under an Ar atmosphere. As soon as the electrolysis was finished, 150 mg of LiAlH4 was added to the solution and refluxed for 12 h. After evaporation of and then re-dissolving in DME, 2 ml of MeLi (3.1 M in DME) was added dropwise into this solution to replace chlorine atoms with methyl substituents which makes PSC resistant against moisture being in the air by increasing hydrophobicity of the polymer backbone. The polymer formed a light-brown powder and about 75 % yields as reported in ref 13.</p><p>Fig. S1 UV/Vis spectrum of PSC. Fig. S2 1H-NMR spectrum of PSC.</p><p>Fig. S3 FTIR spectrum of PSC.</p><p>Synthesis and Characterization of SiO2</p><p>PSC as a precursor was put into alumina ceramic boats and then heated at 1000◦C, at 750◦C and at 500◦C in a tube furnace under an air atmosphere, at a ramp rate of 10◦C/min, held for</p><p>24 h to produce SiO2 and then cooled to room temperature. The crystalline SiO2 obtained was about 40 % yields. All SiO2 samples were characterized by FTIR, Raman and X-ray spectroscopy.</p><p> o Fig. S4 Matching profile of SiO2 ceramics produced at 500 C.</p><p> o Fig. S5 Matching profile of SiO2 ceramics produced at 750 C. o Fig. S6 Matching profile of SiO2 ceramics produced (1000 C).</p><p> o Fig. S7 An optical microscope images of SiO2 ceramic produced at a) 500 C (magnification 100×), b) 750oC (magnification 100×) and c)1000oC (magnification 100×). o o Fig. S8 Scanning electron micrograph (SEM) images of SiO2 produced at a) 500 C, b) 750 C and c)1000oC.</p>