Study of the surface properties of polypropylene by enzyme treatment

Surface modification of polypropylene is performed in this work by enzyme-catalyzed post-processing strategy. The polyDOPA was synthesized by in-situ polymerization in the present of laccase and deposited on the polypropylene surface. The effect of various process variables namely processing step, pH, time, and temperature is studied at various levels. The results show that one-bath and one-step method is the optimal mode. Various functional groups incorporated to the polymer surface are confirmed by attenuated total reflectance-Fourier-transform infrared spectroscopy. The effect of process variables on surface morphology of polymers is evaluated by scanning electron microscopy, revealing that the surface of the polypropylene is covered with thin burrs, and these are regarded as polyDOPA adhered after treatment. Furthermore, the electrostatic charge decay time and contact angle as well as capillary wetting measurements of the modified polypropylene are 0.61 s and 75.33°, respectively, indicating its fine anti-static electricity and better wettability. Besides, this material shows dark gray colors and exhibits excellent ultraviolet-resistance performance. Interestingly, the modification process nearly has no influences on the mechanical property.