Self-assembly Of Amphiphilic Ionic Salts Containing Polynitrogen Heterocycles And Metal Corrosion Inhibition

In recent years,with the increasing awareness of environmental protection,research on high-efficiency and environmentally-friendly corrosion inhibitors has received more and more attention.Among them,nitrogen-containing heterocyclic corrosion inhibitors have received extensive attention due to their excellent properties.Pyridine is a compound containing a nitrogen-containing heterocyclic structure,pyridine and its derivatives are widely used in the fields of medicine,food,and chemical industry.Pyridine has the potential to act as an excellent corrosion inhibitor due to its interaction with the lone pair of electrons on the heterocycle and the metal's empty d orbital.Pyridine corrosion inhibitor could adsorb on the copper surface tightly and form complexes through the nitrogen heterocycles in the molecular structure and the ions formed on the surface of copper,and forming a layer of organic protective film on the surface of copper,which acts as a barrier to metal and corrosion.In this dissertation,a series of organic inhibitors containing triple pyridine rings were designed and synthesized to increase the adsorption centers in molecule of inhibitor.Besides,the hydrophobic alkylene linker which could form a tight barrier as the waterproof is necessary.In order to solve this two problems,we designed a series of triple pyridine containing aliphatic chain with different chain length BHO1?BHO2.The carbon chain lengths were 4 and 6 respectively.In addition,corresponding mono triple pyridine BBO1?BBO2 were synthesized for the comparisons.Since the synthesized mono triple pyridine and double triple pyridine ring inhibitors are poorly water-soluble,the nitrogen-containing heterocyclic ring on the pyridine ring is protonated,so that the target corrosion inhibitor molecule has high solubility in the solution,thereby making its molecular structure.The C=N and C-N bonds in the middle are more favorable for chemical oxime synthesis bond with copper ions,and the protonated hydrophobic chain can play a hydrophobic role,so the alkyl chain is introduced into the pyridine ring to become a quaternary ammonium salt.A corrosion inhibitor,to study its slow release efficiency.In order to further study the adsorption mechanism,a synthetic corrosion inhibitor molecule was added in the EtOH/0.5 M H₂SO₄?v:v=1:1?mixed system.Since the unshared electron pair on the pyridine nitrogen heterocycle can form a stable hydrogen bond between the EtOH/0.5 M H₂SO₄?v:v=1:1?mixed solution and the H₂O molecule.The body is then immersed in a self-assembled film with a stable aggregate solution to avoid corrosion in a 0.5 M H₂SO₄ solution.Scanning tunneling microscopy?SEM?was used to observe the aggregation of corrosion inhibitor molecules in EtOH/0.5 M H₂SO₄?v:v=1:1?mixed system with time and concentration to further study the stable aggregation of copper electrodes in this class.The self-assembly adsorption film formation effect in the system.Ultraviolet spectroscopy,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and dynamic light scattering?DLS?were used to characterize the morphology and size of corrosion inhibitor aggregates.Further use of scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?,Fourier transform infrared?FT-IR?and total reflection infrared?ATR-IR?,atomic force microscopy?AFM?,X-ray diffraction?XRD?,Raman spectroscopy and isothermal adsorption lines to further study the chemisorption mechanism of corrosion inhibitor molecular aggregates adsorbed on copper samples.Electrochemical test was used to detect and analyze the corrosion inhibition effect of the aggregate corrosion inhibitor on the copper surface after self-assembly into a film in 0.5M H₂SO₄ solution.Ultraviolet spectroscopy,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and dynamic light scattering?DLS?tests showed that the four inhibitors synthesized were capable of EtOH/0.5 M H₂SO₄?v:v=1:1?Self-assembly into a regular aggregate in the mixed system,and can be effectively adsorbed on the surface of the copper sample.It has a very good corrosion inhibition effect on copper in0.5 M H₂SO₄ solution,and the best corrosion inhibition concentration is 0.100 mM.At the same corrosion inhibition concentration,the results measured by electrochemical impedance spectroscopy and polarization curves were consistent,and the inhibition efficiency was BHO2>BHO1>BBO2>BBO1.Studies have shown that the increase of adsorption centers in the molecules of such corrosion inhibitors and the growth of fatty carbon chains will increase the inhibition efficiency of corrosion inhibitor aggregates to some extent.Scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?,Fourier transform infrared?FT-IR?and total reflection infrared?ATR-IR?,atomic force microscopy?AFM?,X-ray diffraction?XRD?,Raman spectroscopy and isothermal adsorption lines reveal that the corrosion inhibitor aggregates mainly form a coordination bond by complexing nitrogen atoms and copper atoms to form an adsorption film on the copper surface to suppress metal corrosion.