Association through hydrogen bonding of benzoic acid-terminated poly(dimethylsiloxane) 1 in low-polarity solvents has been studied by FTIR spectroscopy and viscosimetry. At high concentrations, chain extension leads to high viscosity values, whereas at low concentrations, intramolecular hydrogen bonding is responsible for the formation of low-viscosity cyclic species. A quantitative model based on Jacobson-Stockmayer theory and describing the competition between chain extension and macrocyclization is presented. On the basis of this model, the molecular weight distributions of ring and chain fractions has been calculated as a function of concentration in three different solvents. The length of the siloxane backbone has been shown to have a large influence on the cyclic weight fraction and on the average molecular weight.

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Purpose This paper aims to prepare a new modified poly(ester amide) (PEA) resins and use it as a binder for anticorrosive and antimicrobial coatings. Design/methodology/approach New modified PEA compositions were prepared based on 4-amino-N, N-bis(2-hydroxyethyl) benzamide (AHEB) as the ingredient source of the polyol used and evaluated as vehicles for surface coating. The structure of the modifier and PEA resin was confirmed by FT-IR, H¹-NMR, MW, thermogravimetric analysis and scanning electron microscope studies. Coatings of 50±5 µm thickness were applied to the surface of glass panels and mild steel strips by means of a brush. The coating performance of the resins was evaluated using international standard test methods and involved the measurement of phyisco-mechanical properties and chemical resistance. Findings The tests carried out revealed that the modified PEA based on AHEB enhanced both phyisco-mechanical and chemical properties. Also, the resins were incorporated within primer formulations and evaluated as anti-corrosive and antimicrobial single coatings. The results illustrate that the introduction of AHEB, within the resin structure, improved the film performance and enhances the corrosion resistance and antimicrobial activity performance of PEA resins. Practical implications The modified PEA compounds can be used as binders in paint formulations to improve the chemical, physical, corrosion resistance and antimicrobial activity properties. Originality/value Modified PEA resins are cheaper and can be used to replace other more expensive binders. These modified PEA resins can compensate successfully for the presence of many the anticorrosive and antimicrobial paint formulations, and thus, lower the costs. The main advantage of these binders is that they combine the properties of both polyester and polyamide resins based on nitrogenous compound, are of lower cost and they also overcome the disadvantages of both its counterparts. Also, they can be applied in other industrial applications.

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