Synthesis of Resorcinol-Based Phosphazene-Containing Epoxy Oligomers.

Igor A. Sarychev,Irina B. Sokolskaya,Roman S. Borisov,Sergey N. Filatov,Vyacheslav V. Kireev,Jianxin Mu,Julya V. Bilichenko,Igor S. Sirotin

doi:10.3390/polym11040614

Igor A. Sarychev, Irina B. Sokolskaya + Show 6 more

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https://doi.org/10.3390/polym11040614

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Abstract

Phosphazene-containing epoxy-resorcinol oligomers (PERO) are synthesized in one stage with the direct interaction of hexachlorocyclotriphosphazene (HCP), resorcinol, and epichlorohydrin in the presence of solid NaOH. Depending on the initial ratio of HCP:resorcinol, PERO contains from 20 to 50 wt.% phosphazene component (2.0–4.8% of phosphorus) and have an epoxy group content up to 30 %. Products are characterized using 1H and 31P NMR spectroscopy, MALDI-TOF mass spectrometry, and elemental analysis. According to mass spectrometry, the phosphazene fractions of PERO include up to 30 individual compounds with a predominance of cyclotriphosphazenes with one unsubstituted chlorine atom and four or five glycidyl groups. PERO has a lower viscosity in comparison with similar resins based on bisphenol A, which can simplify their use as a binder for polymer composites, adhesives, and paints.

Highlights

Epoxy resins have won a special place in industry and everyday life—though not so much in terms of production, but in their specific role [1]
Classic bisphenol A based epoxy resins have many advantages, including good mechanical and adhesive properties [1,2], which have led to their indispensability as the basis of adhesives, coatings and binding polymer composites [1,3]
Regarding materials based on brominated epoxy resins, as well as other halogen-containing compounds, they contribute to the reduction of flammability, they can emit toxic gases when in contact with a flame, limiting their use for environmental reasons [5,6]

Summary

Introduction

Epoxy resins have won a special place in industry and everyday life—though not so much in terms of production, but in their specific role [1]. Polymers based on neat epoxy oligomers often have detracting characteristics, in particular, flammability and relatively low heat resistance [3]. A rather effective way to increase the heat resistance of epoxy matrices is their structural modification, in particular, with compatible oligomers with higher functionality, which can be incorporated into the three-dimensional network structure formed during curing [3,4]. Regarding materials based on brominated epoxy resins, as well as other halogen-containing compounds, they contribute to the reduction of flammability, they can emit toxic gases when in contact with a flame, limiting their use for environmental reasons [5,6]. One of the most promising methods of modifying epoxy polymers in order to impart heat and fire resistance is the introduction of phosphorus compounds, Polymers 2019, 11, 614; doi:10.3390/polym11040614 www.mdpi.com/journal/polymers

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