Bio-based hyperbranched polyurethanes for surface coating applications

High performance vegetable oil based hyperbranched polymers are not only interesting but also very useful with respect to current scenario of advanced coating materials. So in the present study hyperbranched polyurethanes have been synthesized from the monoglyceride of Mesua ferrea L. seed oil, poly(ɛ-caprolactone)diol, 2,4-toluene diisocyanate and glycerol without using any catalyst by a two-step one pot A2 + B3 approach. The linear analog (neglecting little possible branching due to different components of monoglyceride) of the hyperbranched polyurethane has also been prepared by the same method without using glycerol, just to compare with hyperbranched polymer. The formation of polymers was confirmed by FTIR, 1H NMR, UV and SEM studies and measurements of hydroxyl value, solubility and viscosity. TGA results indicated the high thermal stability of hyperbranched and linear polymers (210–220 °C). The properties like tensile strength, impact strength, hardness, adhesion, flexibility, gloss, elongation at break and chemical resistance were influenced by the hard segment content of the polymers. The hyperbranched polyurethane with 30% hard segment content showed the optimum properties. The values of hydrodynamic diameter of hyperbranched polymers compared to the linear analog support the hyperbranched formation. Thus it confirms the formation of mechanically strong and thermally stable hyperbranched polyurethane coating materials from a vegetable oil.