Журнал "Макрогетероциклы"

Kirill V. Zuev,^a,b@ Valery P. Perevalov,^a Evgeny G. Vinokurov,^a Fedor N. Zhigunov,^a and Tatiana Yu. Koldaeva^a

^aD.I. Mendeleev University of Chemical Technology of Russia, 125047 Moscow, Russia

^bA.N. Frumkin Institute of Physical Chemistry and Electrochemistry RAS, 119071 Moscow, Russia

^@Corresponding author E-mail: zuev.kirill@inbox.ru

DOI: 10.6060/mhc160212z
Macroheterocycles 2016 9(3) 250-256

Recently, the possibility of using phthalocyanine derivatives in the preparation of metal composite coatings was studied. To do this, the soluble phthalocyanine derivatives were used, which provide creating the brilliant coatings with high microhardness. It is also possible to obtain the composite coatings with nanodispersed metal-phthalocyanines (MPc) with a view to their use as anti-friction systems. The main difficulty for creation of such coatings is the instability of aqueous suspensions with MPc particles, which are not wetted by water. There are several methods to stabilize suspensions of water-insoluble phthalocyanine depending on their applications. For the use of MPc as additives to solutions for plating the composite coatings it seems to be appropriate a chemical modification of either the individual MPc molecules, or the surface of molecule aggregates. This method provides the sustained change in the physical-chemical properties of the material. This paper presents the results of studying the method of chemical modification of copper-phthalocyanine (CuPc) particle’s surface by reaction with benzenediazonium salts containing ionic or bulky functional fragments in the aromatic ring. For this, there were synthesized the modifiers with hydroxyl functional fragments: 4-((2-(bis(2-hydroxyethyl)amino)ethoxycarbonyl)benzenediazonium chloride and 4-(bis(2-hydroxyethyl)carbamoyl)benzenediazonium chloride. These compounds were prepared by reacting the 4-nitrobenzoyl chloride with di- and triethanolamines followed by reduction of the nitro-group to the diazotizable amino-group. In addition, the 4-benzenediazonium-carboxylate and the 4-benzenediazonium-sulfonate were used as modifiers. The process of modification involves three steps: 1) catalyzed by acetate-ion formation of aryl radicals from benzenediazonium salts; 2) mechanical activation of the surface by forming a large number of nanoparticles CuPc with excess of surface energy; this process was realized in ball mill; 3) arylation of the aromatic fragments of CuPc followed by fixing the new functional groups on the particle’s surface of phthalocyanine (Gomberg-Bachmann reaction in heterophase conditions). Due to the analysis of the electronic light absorption spectra of modified CuPc aqueous suspensions it was defined optimal amount of modifier - about 3 % by weight of the material being processed. Analysis of surface area MPc particles (by BET adsorption method) and TEM results show that the modification process does not substantially affect the characteristics of powdery CuPc. By results of dynamic light scattering (DLS-method) it was shown that the average size of the modified CuPc aggregates in aqueous dispersions reduces from ~500 nm to ~250 nm. This provided the significant increase of colloidal stability and color intensity of MPc aqueous suspensions. At the same time, for modified CuPc does not appear water solubility. There was a significant change in the electrokinetic (ζ-) potential aqueous suspensions of modified CuPc. For anionic sulfophenyl- and carboxyphenyl- groups the largest absolute value of the ζ-potential was observed at the pH>7. The value of ζ-potential provides the stability for the modified CuPc aqueous dispersions (|ζ|>30 mV). Non-ionic hydroxyl fragments don’t have a significant importance on the value of the ζ-potential and can’t provide electrostatic stabilization of CuPc aqueous dispersions. However, these fragments are capable of forming hydrogen bonds with the molecules of the medium, and their three-dimensional structure making steric factor stability of CuPc suspensions. The position of the isoelectric point (pH at ζ=0) for the initial and modified CuPc aqueous suspensions is changing in accordance to ability of surface functional groups to ionization. Aqueous dispersions of CuPc, stabilized by using described method, can be used as a basis for the deposition of composite metallic coatings with anti-friction properties.

References: