Polyacrylonitrile (PAN)/Sodium silicate (SS) nanocomposite was synthesized via non-conventional emulsifier free emulsion method using an in situ developed transition metal complex Cu(II)/EDTA taking potassium monopersulfate (KMPS) as initiator, with a novel motive of converting hydrophobic homopolymer PAN into hydrophilic nanocomposite by the inclusion of SS to the homopolymer. The formation of the PAN/SS nanocomposite was confirmed by infrared spectra (IR). Furthermore, as evidenced by transmission electron microscopy (TEM), the composite so obtained was found to have nano scale structure. X-ray diffraction (XRD) was carried out suggesting that the silicate layers were exfoliated or intercalated during the polymerization process. An increase in the thermal stability for the developed nanocomposite was recorded by thermogravimetric analysis (TGA). The combustion behaviour has been evaluated using oxygen consumption cone calorimeter and the nanocomposite exhibited good fire retardancy. The PAN/SS nanocomposite was found to be biodegradable as tested by sludge water and further confirmed by scanning electron microscopy (SEM).