Experimental investigation of the feasibility of electro-optic (EO) polymeric devices is reported. A 2 times 2 latch-type EO multimode interference switch is shown to operate at 3.8 V with cross-talk 15 dB and switching time 6 ns. By introducing a macrocyclic polyether in the core for ion-trapping, thermal phase-drift of less than 1 radian for both 25degC and 70degC, after 500 hours of continuous operation, is achieved. This level of phase-drift suggests that EO polymers are attractive material platforms for practical photonic devices.