Alcohol-carboxylate transport in phenyl-based membranes of varying chain length transport

Abstract

As global climate change is a major concern which is accelerated by CO2 emissions, we need to reduce CO2 emissions from the environment. In order to do that, researchers conceptualized CO2 reduction cells which electrochemically convert CO2 to other chemicals such as CO or methanol. A major problem faced by such devices is the crossover of the CO2 reduction products (i.e. methanol (MeOH), formate (OFm-), and acetate (OAc-)) through ion exchange membranes (IEM) which reduces the efficiency of the cell. Therefore, it is critical to design IEMs that suppress the transport of CO2 reduction products. Towards this goal, our group has been investigating the transport behavior of these products in crosslinked PEGDA-based IEMs, where we observed the diffusivities of cation exchange membranes to OFm- and OAc- increased in co-diffusion with MeOH, which is a concerning behavior. Here, we prepared analogous films with a series of phenyl- containing comonomers of different chain lengths [i.e. phenyl acrylate (PA, n = 0), phenyl ether acrylate (PEA, n = 1), and poly(ethylene glycol) phenyl ether acrylate (PEGPEA, n = 3)]. We then measured the permeabilities of these films toto OFm- and OAc-, where we observed the permeabilities of films with the shorter chain length [PEGDA-PA (n = 0)] to be lower than films with longer comonomer chain lengths. This work lays the foundation for further understanding of transport in these films, where in the future we will measure permeabilities to MeOH, cotransport MeOH-OFm-, and MeOH-OAc- as well as the solubilities of these species within the films.