Precision Sulfonic Acid Polyolefins via Heterogenous to Homogenous Deprotection

Polyolefins containing precisely spaced sulfonic acid functionality are made. First, precision ethyl sulfonate ester diene monomers are synthesized, which then are converted to acyclic diene metathesis polymers using Grubbs' catalysis. Subsequently, the poly(ethyl sulfonate esters) are deprotected post‐polymerization via two successful routes, both using a concept of “heterogenous to homogenous deprotection.” The resulting poly(sodium sulfonate) salts are then converted to precise poly(sulfonic acids), where the sulfonic acid functionality is placed either at every ninth or 21st carbon. For comparison, random versions of poly(sulfonates), their salts, and sulfonic acid polymers are synthesized via copolymerization of the “9” sulfonate monomer with 1,9‐decadiene. Precision placement of sulfonic acid functionality could lead to materials of potential utility. Precision sulfonic acid polymers are possible through acyclic diene metathesis (ADMET) and a unique deprotection strategy: “Heterogenous to Homogenous Deprotection,” required to produce a true precision sulfonic acid material. Deprotection is achieved by suspending the polymer in a non‐solvent and reacting the polymer into solution where the reaction is completed. This enabling technique is key to synthesizing these highly tunable acid‐functionalized materials.