The improvement of gas and ion transport in fuel cells, flow battery, electrodialysis, and gas purification technologies can help provide for future demands in the transportation and water sectors.One class of materials that is integral for these processes is ionomers. Specifically, ionomers have exhibited their potential by excelling in key properties such as gas permeability and selectivity, mech. robustness, ionic conductivity, and thermal transitions. The industry standard for many electrochem. based processes is Nafion by Dupont. However, the bicontinous morphol. of Nafion has led to selectivity issues. To overcome this issue while retaining functionality thin film ionomers like homogeneously sulfonated Diels-Alder poly(phenylene) (DAPP) have been created. The homogeneous sulfonation is limited in DAPP as the mech. stability has been shown to be compromised at an ionic exchange capacity greater than 2.2 as a direct result of swelling effects due to sulfonated pendant Ph groups. As an alternative direct post sulfonation completed by a heterogeneous solid-state reaction initially showed promising thermal, mech. and gas transport properties. The aim of the present study is to optimize direct sulfonation effects on DAPP. Current TGA data of a monovalent salt form shows unique thermal behavior leading to the conclusion that various extents of reaction occurred throughout the polymer, i.e., a sulfonation gradient (see figure). Addnl., unique solubility behavior has provided further evidence of a gradient like functionality through visible sheet separation of the polymer in solution Future studies for both acid and salt forms of the polymer include annealing studies in a custom-built inert furnace followed by DMA, DSC, ionic conductivity via EIS, and gas permeation studies in a custom-built system. The morphol. and chem. composition will be done via FTIR and titration studies.