Core/Shell Pigments with Polyaniline Shell: Optical and Physical–Technical Properties

Core/shell pigments allow for the combination of the active anti-corrosion effect of the shell and the barrier effect of the core. This makes it possible to obtain anti-corrosion pigments, with a high—protective effect and low toxicity. Thus, the need for a comprehensive study of the properties of these pigments grows more urgent, before their application to paints and varnishes. The hiding power of core/shell pigments comes close to the one of pure polyaniline (PANi), when the PANi content in the pigment reaches 50 wt.%, with sulfuric and phosphoric acids used as dopants. This paper, also, shows that the blackness value of core/shell pigments with 10 wt.% PANi is around 35 and constant; for pure PANi, their blackness value is 40. When PANi content is 5 wt.%, kaolin-based pigment shows the lowest blackness, which happens due to a generally higher whiteness of kaolin. However, when the PANi content surpasses 10 wt.%, there seems to be no influence on the blackness of the core/shell pigments. The core/shell pigment with a 20 wt.% PANi is, optically, identical to a black-iron-oxide pigment. An increase in the PANi content of the core/shell pigment leads to an increase in the oil absorption of the samples. It was found that the dispersion process would be the most energy efficient for core/shell pigments, containing kaolin and talc as a core

One-Pot Synthesis of Hyperbranched Polyurethane-Triazoles with Controlled Structural, Molecular Weight and Hydrodynamic Characteristics

We report a simple and convenient approach to the one-pot synthesis of hyperbranched polyurethane-triazoles with desirable properties. This method is based on in situ generation of an AB2 + A2 + B4 azide-acetylene monomer mixture of known composition, due to quantitative reactions of urethane formation between isophorone diisocyanate (IPDI), 1,3-diazidopropanol-2 (DAPOL) (in the first stage) and propargyl alcohol (in the second stage). The obtained monomer mixture can be involved in step-growth polymerization by azide-alkyne cycloaddition without additional purification (in the third stage). The properties of the resulting polymers should depend on the composition of the monomer mixture. Therefore, first the model revealing the correlation between the monomer composition and the ratio and reactivity of the IPDI and DAPOL active groups is developed and proven. In addition, the newly developed structural kinetic model considering the substitution effect at polyaddition of the complex mixture of monomers allows the prediction of the degree of branching of the target polymer. Based on our calculations, the hyperbranched polyurethane-triazoles were synthesized under found conditions. All products were characterized by 1H NMR, FTIR, SEC, DLS, DSC, TGA and viscometry methods. It was shown that the degree of branching, molecular weight, intrinsic viscosity, and hydrodynamic radius of the final hyperbranched polymers can be specified at the first stage of one-pot synthesis. The obtained hyperbranched polyurethane-triazoles showed a degree of branching from 0.21 to 0.44 (calculated DB-0.25 and 0.45, respectively)

Synthesis, Antibacterial Activity, and Cytotoxicity of Azido-Propargyloxy 1,3,5-Triazine Derivatives and Hyperbranched Polymers

A new method for the synthesis of azido-propargyloxy derivatives of 1,3,5-triazine has been developed utilizing the nitrosation of hydrazyno-1,3,5-triazines. New hydrazines (2-hydrazino-4,6-bis(propargyloxy)-1,3,5-triazine and 2,4-dihydrazino-6-propargyloxy-1,3,5-triazine) were synthesized and characterized via FTIR, NMR spectroscopy and elemental analysis. The hyperbranched polymers with azide (diazide monomer) and propargyloxy terminal groups were obtained via the azide-alkyne polycycloaddition reaction of diazide and monoazide AB2-type monomers. The antibacterial activity against Escherichia coli bacteria of 2,4,6-trispropargyloxy-1,3,5-triazine, 2-azido-4,6-bispropargyloxy-1,3,5-triazine, and 2,4-diazido-6-propargyloxy-1,3,5-triazine and their hyperbranched polymers was studied. Only 2,4-diazido-6-propargyloxy-1,3,5-triazine has weak antibacterial activity in comparison with ampicillin. The cytotoxicity of these compounds against M-HeLa, FetMSC, and Vero cell lines was also studied. 2,4,6-trispropargyloxy-1,3,5-triazine does not show any cytotoxic effect (IC50 ≥ 280 µM). It was shown that the presence of an azide group in the compound directly affects the cytotoxic effect. Hyperbranched polymers have a less cytotoxic effect against M-HeLa (IC50 > 100) in comparison with monomers (IC50 = 90–99 µM). This makes it possible to use these polymers as the basis for biocompatible materials in biomedical applications

Curing of Poly(styrene-co-methyl methacrylate-co-2-hydroxyethyl methacrylate) Terpolymers in the Presence of Amino Compounds of Different Structures

The process of curing the acrylic oligomers for rapid thermal curing coatings in the presence of hexa(methoxymethyl)melamine (HMMM), tetra(butoxymethyl)glycoluril (TBMG), and tetra(methoxymethyl)glycoluril (TMMG) has been studied. When HMMM is used as a hardener, the content of hydroxyl groups in the terpolymer and also the crosslinking agent concentration have little effect on the initial cure rate. It has been established that during the curing of the TMMG composition, the amount of the network polymer and the initial curing rate decrease at short curing times only. It has also been revealed that the use of butoxy groups instead of methoxy groups as blocking agents leads both to a decrease in the initial cure rate and the gel fraction limiting value from 98 to 80%. When it comes to TBMG-containing compositions, a decrease in the part of hydroxyl groups in the copolymer leads to a significant fall in the initial curing rate and also in the gel fraction content. Regardless of the crosslinking agent used, an acceleration of the curing process is observed with an increase in the catalyst content in the compositions