Template Method To Prepare Polypyrrole And The Anticorrosion Property Of Its Composites

Polypyrrole?PPy?has become one of the most promising polymer materials for industrial applications due to many advantages,such as easy synthesis,good environmental stability,etc.However,the conductive properties of extrinsic PPy is very poor,and the polar and rigid interactions between molecular chains make its solubility extremely poor,which seriously hampers its large-scale applications in various fields.Currently,PPy is used for doping or modified with other polymers to gradually improve its conductivity and dissolution properties,thereby improving its processing performance and expanding its application fields.In this thesis,a series of doped PPy with different morphology were firstly prepared by chemical oxidation method using pyrrole?Py?as the monomer,Fe Cl₃ as the oxidant,different anionic and cationic surfactants?PTSA,TSA,DBSA,SDBS,MO,2A1,and CTAB?and self-made gemini surfactant?GS16-2-16?as the dopants.The effects of surfactant's type and dosage on the properties of PPy were discussed separately.The results showed that the type and dosage of surfactant significantly affected the mor phology and the conductivity of PPy.The TSA-PPy has higher thermal stability and molecular orientation,and the electrical conductivity can reach to 13.6 S/cm.Poly?vinyl alcohol??PVA?is usually used as matrix material in modification of polymers because of its excellent water dispersibility and great film-forming performance.In order to further improve the waterdispersibilityofTSA-PPy,aseriesofpolyvinyl alcohol/polypyrrole dispersions?PVA/PPy?were prepared using PVA as polymer stabilizer and dispersant,Fe Cl₃ as oxidant and TSA as dopant with the method of in-situ polymerization.The result showed that PVA significantly improved the water dispersion of PPy.The as prepared dispersion was then physically mixed with aqueous epoxy resin?EP?to prepare a series of waterborne PVA/PPy/EP corrosion protection coatings.FTIR,TEM,SEM,XRD and other characterize methods were used to study the effects of different Py dosage on the structure,morphology and molecular orientation of PVA/PPy.The electrochemical workstations were also used for analysis and testing,the influence of Py dosage on the anticorrosion property of PVA/PPy.The results showed that the resistance value of PVA/PPy-40%/EP composite anticorrosive coating reaches the maximum in the low frequency region,which can reach to 1.038×10⁸?·cm².The addition of PVA/PPy-40%increases the corrosion potential from-0.59V to-0.36V.Phosphate has the property of water resistance,mechanical strength and metal release,and were often used as a metal corrosion inhibitor in the preparation of anti-corrosive coatings.In order to further improve the anticorrosion property of composite coatings,phosphoryla ted poly?vinyl alcohol??P-PVA?was used to synthesize a series of P-PVA/PPy dispersions.The P-PVA/PPy/EP anticorrosion coating s were then prepared.The effects of different phosphorylation levels on the structure and properties of P-PVA/PPy composites were studied.Through performance tests and characterization results,the phosphate group in P-PVA on the one hand destroys the ordering arrangement of-OH in the PVA molecular chain,therefore reducing the effect of intermolecular hydrogen bonding and gra dually increasing the water resistance of composite material.The water resistance of the P-PVA-8.0%/PPy-40%is only 3.4%.On the other hand,the phosphate group can form a passivation film with Fe HPO₄ and Fe₃?PO₄?₂ as the main components on the surface of the iron steel,thereby producing a synergistic effect with the PPy passivation film s and slowing down the corrosion of small molecule on the metal surface,and further improves the corrosion resistance of aqueous EP.Electrochemical results showed that when the degree of phosphorylation is 8.0%,the resistance value of P-PVA-8.0%/PPy-40%/EP coating could reach to 7.262×10⁹?·cm²,and the corrosion potential is-0.31V.P-PVA-8.0%/PPy-40%/EP coating shows excellent corrosion resistance,therefore it can be applied to the field of metal protection.