On improving the physical properties of poly (urethane urea)s by the inclusion of aromatic amines connected through long aliphatic chains in the hard domain

Abstract

In order to improve to obtain improved physical properties, new poly (urethane urea)s were obtained by the reaction of the PCL-HDI urethane pre-polymer with poly(1,4-butanediol)bis(4-aminobenzoate (PBBA) or with PBBA and different crosslinkers. The formation of the characteristic groups (i.e. urethane and urea groups) and their non-covalent interactions (such as hydrogen bonding) were analyzed by FTIR spectroscopy. The high thermal stability of the obtained polymers (up to 300–350 °C) is the result of the PBBA structure. The incorporation of PBBA into the polymer backbone generated improved mechanical properties, with a maximum tensile strength of up to 45 MPa and elongation at break of up to 1100 %. These results can be explained by the fact that the inclusion of PBBA increased mobility of the polymer in the area of the hard domain. In addition, this study showed that a higher amount of PBBA does not further increase the mobility of the polymer material. Water contact angles were used to evaluate the hydrophobic performance of the obtained polymer films. The paper also assesses the changes in the structure and morphological appearance, mechanical properties and evolution of the sample surfaces that occurred after different periods of exposure to UV radiation in a UV illumination chamber. The behavior of UV-irradiated poly (urethane urea) films depends on the molecular structure of the hard domains. The new poly (urethane urea) materials offer attractive physical properties for new engineering applications requiring higher mechanical strength and thermal stability.