Abstract: A copolymer composition including a copolymer having repeat units of structural formula I: where X is selected from —CH2—, —CH2—CH2— and O; m is an integer from 0 to 5; and each occurrence of R1-R4 are independently selected from H; C1 to C25 linear, branched, and cyclic alkyl, aryl, aralkyl, alkaryl, alkenyl and alkynyl that can include one or more hetero atoms selected from O, N, and Si; a group that contains an epoxy functionality; —(CH2)nC(O)OR5; —(CH2)nC(O)OR; —(CH2)nOR6; —(CH2)nOC(O)R6; —(CH2)nC(O)R6; —(CH2)nOC(O)OR6; and any combination of two of R1, R2, R3, and R4 linked together by a linking group. A portion of the repeat units having structural formula I contain at least one epoxy functional pendant group. The copolymer composition can be included with a material that photonically forms a catalyst in a photodefinable dielectric composition, which can be used to form a photodefinable layer on a substrate.