Preparation, release and anticorrosion behavior of a multi-corrosion inhibitors-halloysite nanocomposite

Sodium Lignosulfonate-Loaded Halloysite Nanotubes/Epoxy Composites for Corrosion Resistance Coating

Corrosion resistance coating applied on Q235 carbon steel in a chloride-rich environment was explored in our research. The coating as a barrier inhibits the penetration of the corrosion medium and provides active corrosion protection for Q235 carbon steel. Halloysite nanotubes (HNTs) were loaded with sodium lignosulfonate (SLS) under vacuum conditions. 4.53% of loading efficiency was validated by thermogravimetric analysis (TGA). The deposition of polyelectrolyte layers including poly(dimethyl diallyl ammonium chloride) (PDDA) and poly(styrenesulfonate) (PSS) not only resulted in controlling the release rate of SLS but also enabled the HNTs to possess pH-responsive release property. The modified HNTs were defined as "PSS/PDDA/SLS/HNTs", which were characterized by SEM, TEM, FTIR, and zeta potential analyses. TGA elucidates that PSS/PDDA/SLS/HNTs exhibit superior thermal stability. The results of UV-vis spectroscopic analysis confirm that HNTs exhibit a higher release amount in an alkaline medium than in neutral and acidic conditions. Afterward, PSS/PDDA/SLS/HNTs were mixed with the epoxy coating, which was applied on Q235 carbon steel immersed in 3.5 wt % NaCl solution. Electrochemical measurements illustrate the excellent corrosion resistance of the epoxy coating with the addition of PSS/PDDA/SLS/HNTs. Also, water contact angle analysis demonstrates the modification of the epoxy coating with decent hydrophobicity.

Poly(Methyl Methacrylate) Coatings Containing Flame Retardant Additives from Suspensions in Water-2-Propanol

A dip-coating technique is designed for deposition of poly(methyl methacrylate) (PMMA) from water/2-propanol mixture, avoiding the use of traditional toxic solvents. Solutions of PMMA macromolecules with high molecular weight (MW) are obtained for a water/2-propanol ratio of 0.15-0.33 and the solubilization mechanism is discussed. The ability to use concentrated PMMA solutions and high MW of the polymer are the key factors for the successful dip coating deposition. The coating mass for 10 g L-1 polymer solutions shows a maximum at a water/2-propanol ratio of 0.25. The deposition yield increases with the polymer concentration increase and with an increasing number of the deposited layers. PMMA deposits protect stainless steel from aqueous corrosion. The coating technique allows for the fabrication of composite coatings, containing flame-retardant materials (FRMs), such as commercial halloysite, huntite, hydrotalcite, and synthesized Al(OH)3, in the PMMA matrix. The FRM content in the coatings is modified by variation of the FRM content in colloidal suspensions. A fundamentally new method is developed, which is based on the salting out aided dispersive extraction of Al(OH)3 from the aqueous synthesis medium to 2-propanol. It is based on the use of hexadecylphosphonic acid molecules as extractors. The method offers advantages of reduced agglomeration.