A regioselective route to negative coefficient of thermal expansion materials for tuning epoxy thermomechanics

Thermoset polymers are widely used due to their low cost and versatile high-performance material properties. These materials have found primary applications as heterogenous mixtures (composites) in adhesives, encapsulants, and more. However, thermosets and composites are known to have large coefficients of thermal expansion (CTE), which differ from the CTE of the substrates they are often applied to. A large CTE mismatch results in localized stress and sometimes cracking of the substrate, precluding utility of such thermosets/composites in certain applications, such as optoelectronics where adhesives and encapsulants would be highly beneficial. Remedies for this problem include using fillers such as silica or inorganic metals to lower the CTE of the composites, but these solutions can increase the mass and materials cost and shorten device lifetime. The incorporation of negative coefficient of thermal expansion (NTE) materials into the polymer backbone as a tunable handle has emerged as a promising alternative. The following thesis will describe a six-step regiospecific synthesis to obtain a diepoxy-substituted dibenzocyclooctene (DBCO) derivative that is anticipated to exhibit improved NTE behavior relative to state-of-the-art materials