Zero Thermal Expansion Polyarylamide Film with Reversible Conformational Change Structure

Interface failure due to thermal mismatch is one of the culprits that shorten life cycle of devices. In this work, we prepared a series of free-standing cross-linked polyarylamide films with tunable thermal responsive behaviors. By incorporating thermal contractile units, s-dibenzocyclooctadiene (DBCOD), which shrink as a result of thermally induced upconversion from twist boat to chair, negative, zero, and positive coefficients of thermal expansion (CTE) have been realized with the values of CTE ranging from -17.7 to 57.1 ppm/K (20-150 degrees C). This wide tunable CTE window allows the as-prepared cross-linked polyarylamide films to match desired thermal performance for specific applications. Zero-expansion polymer film without the need for inorganic dopants has also been obtained. Such a series of free-standing polyarylamide films with tunable thermal responses showed great potential for many practical applications.