Synthesis and characterisation of polyurethane made from pyrolysis bio-oil of pine wood

•Polyurethanes were synthesised from fractions of pyrolysis bio-oil.•Pyrolytic lignin was found to produce flexible polyurethanes.•Slow addition of pyrolytic lignin to the isocyanate was critical.•Resulting polyurethanes absorb 30 wt% water, but show low diffusivity.