Synthesis of Resorcinol-Based Phosphazene-Containing Epoxy Oligomers

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.

Benzoxazine monomers based on aromatic diamines and investigation of their polymerization by rheological and thermal methods

“…It can be explained by bisphenol A and resorcinol spacers in the structure of P‐bapp and P‐tper correspondingly. For example, resorcinol‐based epoxy oligomers are known to have lower viscosity compared to bisphenol A‐based epoxides 48 . Similarly, P‐tper monomer has about five times lower viscosity compared to P‐bapp monomer.…”

Synthesis and Application of Arylaminophosphazene as a Flame Retardant and Catalyst for the Polymerization of Benzoxazines

“…The other example is hexaphenoxycyclotriphosphazene, which is used as a highly effective flame retardant for a large number of synthetic polymers. A number of effective flame-retarded functional epoxy resins, amine curing agents and benzoxazines with a phosphazene core have been proposed [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Carboxyl-containing epoxyphosphazenes and their use as a catalyst for the polymerization of benzoxazines have also been reported [ 22 ].…”

Isothermal Kinetics of Epoxyphosphazene Cure

“…Different types of product, whether resins, flame retardants or curing agents that can be easily obtained on the basis of universal halophosphazenes, are responsible for the undying interest of researchers in phosphazenes [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. Arylphosphazenes compared with other organophosphorus compounds, have, as a rule, higher thermal stability and chemical resistance and are promising fire retardants [ 4 , 6 , 13 , 14 ], characterized by the synergistic effect of phosphorus and nitrogen [ 15 ]. Thus, phenoxycyclophosphazenes were commercialized as a flame retardant by Otsuka Chemical et al Recently it was shown that epoxy-amine matrices modified with epoxycyclophosphazene [ 16 ] are characterized by enhanced mechanical properties [ 17 ].…”

“…Therefore, epoxy resins modified with epoxycyclophosphazenes appear to be a promising base for halogen-free binders for critical use. Recently, scalable methods for epoxycyclophosphazene synthesis have appeared [ 6 , 16 , 18 ], which make it possible to believe that they may become available starting components in the market for composite manufacture.…”