New structures of polymers containing phosphorus in the main chain were prepared by interfacial polycondensation of phenylphosphonic dichloride with 4,4’-(1,3-phenylenediisopropylidene) bisphenol (bisphenol M) using two different methods: method I: gas–liquid interfacial polycondensation without an organic solvent and a catalyst; and method II: solid–liquid interfacial polycondensation using green solvents and without catalyst. The aim of this work was to apply these methodologies as eco-friendly and economical procedures for a green chemistry. The polymers were characterized by gel permeation chromatography (GPC), FT-IR, ¹H and ³¹P-NMR spectroscopy, differential scanning calorimetry (DSC) and thermal analysis. Yields in the range of 88.0–90.0, and inherent viscosities in the range of 2.2–3.2dl/g were obtained. High molecular weight polymers (57 600–114 400) have been successfully prepared. The polymers are self-extinguishing and begin to lose weight at around 300°C. The flammability was investigated by measuring limiting oxygen index values (LOI).