Synthesis and properties of side chain fluorinated polyurethanes and evaluation of changes in microphase separation

Abstract

To develop marketable new waterproof and breathable membranes, this study successfully applied a simple synthesis method to combine pentadecafluorooctanoyl chloride and 2-Amino-2-methyl-1,3-propanediol into a novel long-segment side-chain fluorinated chain extender (AMPF), the structure was examined using nuclear magnetic resonance (NMR) spectroscopy. To promote environmental-friendliness, biodegradable polycaprolactone (PCL) was chosen to supply the soft segment of polyurethane (PU), methylene diphenyl diisocyanate to supply the hard segment, The successful introduction of AMPF into the PCL-based PU enabled the production of AMPF/PUs. To investigate the effect of AMPF on PCL-based PU, NMR and gel permeation chromatography were performed for the preliminary analysis of AMPF/PUs; curve fitting was applied in Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The atomic force microscopy to determine the difference in van der Waals forces and microphase separation in AMPF/PUs; a thermal gravimetric analysis and dynamic mechanical analysis were conducted to determine the thermal properties of AMPF/PUs, and tensile test were conducted to determine the mechanical properties of AMPF/PUs. The results reveal that AMPF/PUs have a high degree of microphase separation, and the heat resistance of AMPF/PUs can be improved by 4–5 %, while the tensile strength can be increased by about 28 MPa with the increase of AMPF content. From the contact angle test, it is known that the increase of AMPF content can convert the hydrophilic polyurethane (77.8 ± 2.7°) into the hydrophobic (95.2 ± 2.1°) polyurethane. Therefore, it is shown that AMPF can not only improve the strength of polyurethane but also provide hydrophobic properties. This fluorinated chain extender shows considerable potential for the coatings materials and waterproof and breathable fabrics.