Synthesis Of Polyaniline/mesoporous-silica Containers And Its Application For Anticorrosion Coatings

Nowadays, huge economic losses and hidden trouble caused by corrosion degradation have aroused scientific interest. To retard corrosion degradation,self-healing anti-corrosive coating has been developed as one of long-term and smart corrosion-resistant coatings. To obtain more efficient coatings, it is important to develop nanocontainers. One of widely applied containers is mesoporous silica because of its high specific surface-area, large pore volumes and fast-releases of inhibitors. However it cannot provide active protection to metal like most type of containers. It will be interesting and more effective if the containers can form passive films on the surface of metalintrinsically.Polyaniline is one of promising materials for nanocontainers because of its low cost, easy preparation and controllable morphology. To combine advantages of mesoporous silica and polyaniline, a novel container based on polyaniline encapsulated mesoporous silica core(p-SP/PANI or container) has been firstly prepared via in-situ polymerization and surface-protected etching. FTIR, XRD, SEM, TEM and TGA have been used to characterize the structure, crystallization, morphology and thermostability of as-prepared materials. Moreover, BET was used to characterize thepore-size distribution of container before and after loading BTA. UV-Vis was applied to study the release of BTA. Five types of coatings systems(Ep, pS-Ep, Con-Ep, BTA-pS-Ep and BTA-Con-Ep) have been prepared. The self-healing anticorrosion performances of them were estimated by EIS and polarization curves in 3.5 wt% NaCl solution.The results show that the optimum etching time is 110 min and the new type container based on polyaniline encapsulated mesoporous silica core has been successfully prepared. TGA curves indicate that the thermostability of p-SP/PANI is better than solid SP/PANI. EIS and polarization curves show that Con-Ep system performs better than Ep and pS-Ep systems. Additionally, Con-Ep system shows ability of self-repaired anticorrosion. Results of XRD demonstrate the BTA is encapsulated in container with shape of little crystalline granular. UV-Vis shows that BTA releases very fast from containers in water, which means the BTA in container is able to response the penetrative H2 O in coatings in process of immersion. Pore-size distribution of container before and after loading BTA suggests BTA has taken up the most room of container. The possible self-healing anticorrosion performances are evaluated by EIS and polarization curves indicate that the coating including BTA-loaded containers performs better thanthat of BTA–pS–Ep. To sum it up: the strategy of modifying pS by PANI is effective and successful.