Synthesis and characterization of flame retardant hyperbranched polyurethanes for nano-composite and nano-coating applications

Flame retardant hyperbranched polyurethanes were prepared by reacting phosphorous containing triol (tris(bisphenol-A) monophosphate), Castor oil, polyethylene glycol with different isocyanates like TDI, IPDI and HMDI via A2+B3 method. Characterization was carried out by using chemical and instrumental analysis. Using these polyurethanes nano-composites and nano-coating were prepared and their flame retardant, thermal and mechanical properties were found out. •Phosphorus containing hyperbranched polyurethanes have been synthesized.•Elemental analysis, FTIR, NMR spectra give the evidences of the structures.•Nano-composites and nano-coatings have been developed using organomodified clay.•Addition of 3% nano-clay causes 50% improvement in scratch hardness of nano-coatings.•Use of 3% nano-clay enhances 10–12% tensile properties of nano-composites. Flame retardant hyperbranched polyurethanes were prepared by reacting phosphorous containing triol, tris(bisphenol-A) mono phosphate, castor oil, and polyethylene glycol with different diisocyanates like TDI, IPDI and HMDI via A2+B3 method. In this method A2 reactants were diisocyanates along with castor oil and polyethylene glycol whereas phosphorous containing triol was used as B3 reactant and dibutyltin dilaurate (DBTDL) was used as catalyst. Synthesized polyurethans were characterized by gel-permeation chromatography (GPC), elemental analysis, Fourier transform infrared spectroscopy (FTIR) and 1H NMR spectroscopic techniques. Neat polyurethanes were used for preparing films. Nano-clay composites were prepared with various concentration of organomodified montmorillionite nano-clay. Flame retardant, Thermal and mechanical properties of these hyperbranched polyurethanes and their nano-composites were found out. The polyurethanes and their formulations with nano-clay were also used for the coating of mild steel panels. Scratch, pencil, and impact hardness, flexibility and adhesion properties of coated panels were also determined. Observations show an increase in the scratch hardness and flexibility with the introduction of clay. All the coatings show excellent chemical resistance properties compare to their linear counterpart.