Synthesis and characterization of cationomeric AB crosslinked polyurethane polymers based on different chain extenders

Novel AB crosslinked polymers (ABCP) have been synthesized from polyurethanes having tertiary nitrogen atoms using different chain extenders and subsequently crosslinked with bromine terminated polyurethane. The polyurethanes containing tertiary nitrogen atom were synthesized using four different chain extenders viz., N-methyl diethanolamine (N-MDEA), 3,5-pyridine dimethanol (PDM), N,N′-bis(2-hydroxyethyl)isonicotinamide (BHEIN) and 2,3-dihydroxy pyridine (DHP). The multiple tertiary nitrogen sites of polyurethane backbones were further crosslinked with bromine terminated prepolymer. The resulting ABCPs were characterized using Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), contact angle measurements and mechanical analysis. FTIR spectral results confirmed quaternisation of the tertiary nitrogen leading to crosslinking. A comparative study of the properties of crosslinked polymers based on the different chain extenders was done and the results showed that N-MDEA-based ABCPs were more effectively crosslinked compared to other systems. Static mechanical measurements showed higher elongation and tensile strength for N-MDEA-based ABCP. Static contact angles of the cast films of these polymers were determined and the results indicated that the nature of the chain extenders clearly modulated the surface polarity as well as other related interactions. Comparison of dynamic mechanical spectra revealed that BHEIN-based ABCP have good damping.