Synthesis of metal incorporated low molecular weight polyurethanes from novel aromatic diols, their characterization and bactericidal properties

Low molecular weight polyurethanes with sites for metal complexation were synthesized. The –SO2 and the –COOH groups were incorporated into the polyurethane chain by the reactions of tri-functional monomers, 4,4′-bis(hydroxyphenyl)sulfone and 4,4′-bis(hydroxyphenyl) valeric acid with hexa-methylene di-isocyanate (HMDI) and 2,4 toluene di-isocyanate (TDI), respectively. The reaction was monitored from the disappearance of the –OH group and results show that the –NCO groups of the isocyanate reacted with the –OH group preferentially when compared to the other reactive groups. The pristine tri-functional monomers themselves formed stable complexes with the metals and so were chosen to be incorporated into the polyurethane chain. These polymers were characterized by IR and NMR spectroscopy. The free –SO2 and the –COOH groups were used for metal complexation using non-toxic metals like zinc and silver. The anti-bacterial studies conducted on the six polymers in film form showed interesting results as elaborated in the paper.