(462c) Novel Spirocyclic Polymers for Membrane-Based Organic Solvent Separations

Solution-processable microporous polymers have the potential to outperform traditional polymeric membranes in the area of organic solvent separations. In this work, novel spirocyclic polymers were incorporated into thin-film composite membranes with the aim of improving solute rejection when compared against current spirocylic polymers such as PIM-1. The separation system of interest is a complex mixture of hydrocarbon solvents that are typically found in the light fractions of crude oil. These compounds were utilized not only to create a molecular weight cut-off (MWCO) curve, but also to assess the performance of this class of membranes in the fractionation (as opposed to purification) of complex mixtures. We find that the novel spirocyclic polymers have higher rejections than PIM-1 membranes, although the permeances are lower using our non-optimized thin film composite fabrication techniques. A MWCO of ~ 250 Da can be obtained, which is accompanied by high selectivities amongst different classes of hydrocarbons of a similar size. Moreover, high selectivities are also observed amongst molecules within the same class with only sub-nm difference in size. Such size- and shape-selective separation enables the use of these polymeric membranes in a wide range of applications.