Alkyne-Substituted Deoxybenzoins As Precursors to Cycloaddition Chemistry and the Preparation of Low-Flammability Polymers and Blends

We report the synthesis and characterization of novel alkyne-substituted deoxybenzoins that are setup for azide-alkyne cycloaddition chemistry to yield oligomeric and polymeric structures that exhibit useful thermal properties, both on their own and as components of blends with commodity polymers. Low-flammability molecules and macromolecules of the type described here, which are devoid of halogen or phosphorus components, are of growing interest for achieving sustainable solutions to the inherent flammability problem associated with organic polymers. These newly synthesized deoxybenzoin-containing structures were found to possess exceptionally low heat release capacity (HRC) values, below 100 J/g-K, as determined by microscale combustion calorimetry (MCC), while thermogravimetric analysis (TGA) revealed an impressive combination of thermal stability and a high char residue. Utilizing alkyne-substituted deoxybenzoins in azide-alkyne cycloaddition reactions gave access to deoxybenzoin-based polymers with improved solubility and processability relative to prior versions of linear deoxybenzoin-based polymers. Moreover, the triazole units resulting from the cycloaddition reactions further contribute to their low flammability. Overall, this triazole-rich polymer design is envisaged to generate an attractive new category of halogen-free flame-retardant materials with potential for effective use as additives, coatings, fillers, and the like.