Synthesis and controlled release kinetics of pH-sensitive hollow polyaniline microspheres encapsuled with the corrosion inhibitor

Abstract

It has long been a question of great interest in a wide range of fields including smart organic coatings to develop environmentally sensitive drug-loaded micro-storage system and to study its controlled release law. Herein, we first report a novel one-step approach for the synthesis of inhibitor-encapsuled polyaniline hollow microspheres (MBT@PANI) with pH sensitive response and controlled release function based on supramolecular in situ interfacial polymerization technique. An accurate and reliable HPLC method for quantitative determination of the corrosion inhibitor MBT has been established. The pH sensitive controlled release behavior and kinetic mechanism of MBT in 3.5% NaCl solutions were systematically investigated. It was found that the average particle size of the synthesized MBT@PANI microspheres was 1.7 μm and the encapsulation efficiency and the loading of corrosion inhibitor MBT was above 99% and 23.5% (wt.), respectively. The MBT@PANI microspheres exhibited an outstanding feature of long-term sustainable controlled release in 3.5% NaCl solutions with different pH values, and as the pH of the release medium increased, the release rate and cumulative release amount of MBT gradually increased. With the prolonging of the release time, the release process of the inhibitor MBT had three stages and sequentially obeyed the Elovich, first-order and zero-order kinetics. The possible mechanism of pH sensitive controlled release was discussed.