Organic mixed ionic electronic conductors (OMIECs) are conjugated polymer systems that conduct both ions and electrons. They are promising materials for biosensors, neuromorphic computing platforms, and energy storage devices. An obstacle for these new materials is the lack of understanding of the fundamental processes that underlie operation, namely the coupled dynamics of ion motion, electron transport, and structural changes. This work presents the electropolymerization and characterization of thiophene-based polymers and copolymers. One advantage of electropolymerized materials is that they do not require bulky side chains to dissolve in organic solvents, allowing them to hold more charge per volume. Using electropolymerization, we synthesize several polythiophenes with different side chain chemistries. We investigate ion injection kinetics in these materials using spectroelectrochemistry and find that injection kinetics depend on the identity of the electrolyte. We also characterize their morphology with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electropolymerized OMIECs may play an important role in the advancement of OMIEC-based technologies due to their unique morphologies and ease of synthesis.