Organic electrochemical transistors (OECTs) have emerged as artificial synaptic devices that can realize biological synapses through the polymer channels that can transport both ions and charges. Most studies have focused on conjugated polymers as suitable channel materials due to their ability to control ion transport. In particular, the incorporation of glycol-based side chains can improve both packing efficiency and ionic accessibility, enhancing the non-volatile properties of neuromorphic devices. However, conjugated backbone modulation, which plays a crucial role in both charge transport and ion doping, has not been systematically addressed. In this work, we present a strategy to control both ion transport and doping properties via conjugated polymer backbone modulation. This approach suggests potential for the development of non-volatile artificial synapses in OECTs.