Polyurethane encapsulated carbon black particles and enhanced properties of water polyurethane composite films

Polyurethane-encapsulated carbon black (ECB) particles were synthesized successfully through a facile method by encapsulating carbon black (CB) particles in the presence of an amphiphilic isocyanate-terminated polyurethane pre-polymer. Fourier transform infrared spectroscopy demonstrated the existence of a polyurethane layer on the surface of encapsulated CB, and thermo-gravimetric analysis indicated the encapsulation percentage reached 15.77 wt.%. The results of dynamic light scattering, transmission electron microscopy, and UV–vis spectroscopy analyses revealed that the ECBs exhibited better dispersibility and stability in water in comparison with the dispersant-dispersed carbon black (DCB) prepared by simply dispersing CB particles using a polymer super-dispersant. In particular, scanning electron microscope observation of PUB/ECB composite films obtained by blending ECB particles with a waterborne polyurethane binder (PUB), showed enhanced dispersibility and compatibility of the ECBs in the PUB matrix. Therefore, as test results demonstrated, PUB/ECB composite films showed better mechanical, water resistance, and color properties compared with those of PUB/DCB composite film. It is expected that this effective encapsulation method for preparing functional CB dispersions will be used to make waterborne coatings in the leather and textile finishing fields.