Rational design of phosphorylated poly(vinyl alcohol) grafted polyaniline
Phosphorylated poly(vinyl alcohol) (PPVA) was demonstrated to be more effective to improve the dispersion stability of polyaniline (PANI). Phosphate groups also can improve corrosion resistance, but they may spatially interfere with graft reaction of PANI onto PPVA.
Therefore, it is of great significance to explore the balance between phosphorylation degree, graft reaction and composite performance. Here, EPPVA-grafted-PANI (EPPVA-g-PANI) dispersions were prepared by chemical grafting polymerisation of aniline on the epichlorohydrin modified PPVA (EPPVA) with different degree of phosphorylation (DP). It was found that DP has a considerable effect on microstructure, rheological behaviors, as well as the compatibility between EPPVA and PANI. Enhanced interactions and compatibility were demonstrated for EPPVA-g-PANI-8.00 %, resulting in the increase of tensile strength from 26.84 to 38.62 MPa.
Excellent long-term corrosion resistance
As-prepared EPPVA-g-PANI dispersions can be directly blended with waterborne alkyd resins (WAR) without complex post-process to fabricate high-performance WAR/EPPVA-g-PANI nanocomposites. Compared with WAR, the impedance modulus of WAR/EPPVA-g-PANI increased from 8.81×104 to 3.03×1010 Ω·cm2, corrosion current density decreased to 3.02×10−8 from 1.78×10−6 A·cm−2. Additionally, only one time constant was detected after 480 h immersion, further demonstrating excellent long-term corrosion resistance for WAR/EPPVA-g-PANI.
The study has been published in Progress in Organic Coatings, Volume 140, March 2020.