A polymer comprises at least two types of monomer units selected from: (1) diethynyl benzene units, (2) triethynyl benzene units, and (3) ester units. After curing, the polymer may form a condensed polyaromatic dielectric having a dielectric constant of at most 2.0 at 1 MHz, an elastic modulus of at least 7.7 GPa, and a hardness of at least 2.0 GPa.