COMMITTEE CHAIR: Dr. Matthew Minus

TITLE: THE TWO TALES OF ONE STUDENT: BORON-SILICON-FLUORINE EXCHANGE, AND THE QUEST FOR RECYCLABLE VITIRIMERS

ABSTRACT: Vitrimers are a class of dynamic covalent polymer networks that combine the mechanical robustness of thermosets with the reprocessability, and self-healing capabilities enabled by associative bond exchange. Here, we report a new vitrimer system based on dynamic acyl hydrazone linkages formed through condensation of readily accessible aldehyde and hydrazide building blocks. The resulting materials exhibit tunable mechanical properties, self-healing behavior, and thermal responsiveness, while maintaining structural integrity characteristic of crosslinked networks. The system is synthesized under mild conditions without the need for external catalysts and utilizes inexpensive, commercially available components, enabling straightforward and scalable preparation. The influence of processing parameters on network formation, homogeneity, and material performance is examined, establishing key structure–property relationships. This work introduces an accessible platform for acyl hydrazone-based vitrimer materials and highlights their potential for sustainable, reprocessable polymer applications. As the most abundant metalloids on earth boron and silicon play important roles in chemistry, allowing for the synthesis of a wide array of useful small molecules and materials. Fluoride is known to react with boron and silicon atoms. Fluoride etching of silicates is a common reaction with glass materials. Fluorides readily react with aryl boronic acids to yield aryltrifluoroborates that are commonly used in aromatic cross-coupling reactions. Herein, we explore fluoride exchange between potassium aryltrifluoroborates and triethoxyphenylsilane. We further explore the fluorine exchange between different phenyl boronic acids and trifluorophenylsilane. NMR analysis allows us to conclude that fluoride favors the formation of bonds to boron while silicon preferentially bonds to oxides over fluoride. Finally, we demonstrate that this fluorine exchange can be used as a molecular template to cross-couple aromatic rings in air at room temperature.

Keywords: Vitirmer, recycling, fluoride, boron, silicon, cross coupling

Room Location:  EE O’Banion Science Building, RM 203.