UV protection by the inclusion of the methoxybenzophenone moieties into the backbone chain of the polyurethane structure

The paper studies the synthesis and the characteristics of polyurethane elastomers that include in the main polymer chain various amounts of 2,2′-dihydroxy-4-methoxybenzophenone, an organic sunscreen compound. The structure and bonding of the different functional groups were evaluated by Fourier transform infrared spectroscopy. The thermal properties of the polyurethane films were investigated by thermogravimetric analysis in air atmosphere. The results showed that the increase of the 2,2′-dihydroxy-4-methoxybenzophenone amount incorporated into the polymer increases the maximum decomposition temperature and the amount of char residue. Changes in the film surface morphology, induced by UV radiation, were studied by contact angle measurements and scanning electron microscopy. Also, the behavior of the physical characteristics of the polyurethane materials exposed to UV radiation for different time periods was studied. The polyurethanes which include a low amount of the 2,2′-dihydroxy-4-methoxybenzophenone into their structure show good resistance to UV radiation, with small changes in the mechanical properties and surface morphology. Thus, the inclusion of the 2,2′-dihydroxy-4-methoxybenzophenone in the main polyurethane chain has improved the lifespan of these polyurethanes exposed to UV radiation.