We have synthesized a group of functionalized polyethylenes containing precisely placed sulfonic acid moieties. Acyclic Diene Metathesis (ADMET) polymerization was conducted to yield a sulfonic acid functionality on every ninth, fifteenth, and twenty-first carbon of the backbone. Ester protected prepolymers were necessarily synthesized first, followed by a novel deprotection procedure to achieve the desired sulfonic acid functionality without poisoning the catalyst. Protected symmetrical diene monomers were afforded by the alkylation of ethyl methanesulfonate. Weight-average molecular weights up to 40,000 g/mol were achieved. Subsequent hydrogenation of the ester protected prepolymers yielded saturated polyethylene backbones. Complete deprotection of the ester moieties is required to retain the precision, or else a random placement of esters and acids would exist throughout the polymers. We have developed a new methodology for quantitative ester deprotection of polymers by suspending the polymer in nonsolvent and beginning a hydrolysis reaction, for which the product is soluble in the solvent. This deprotection procedure ensures that the polymer is quantitatively deprotected by continuing the reaction in solution. Ester hydrolysis was confirmed by 1HNMR and 13CNMR. Future studies will comprise thermal and morphological data development (e.g., DSC, TGA, x-ray diffraction). These sulfonic acid-containing polymers will add to the library of precise acid-containing polymers our group has already developed, including precision boronic, carboxylic, and phosphonic acids. Sulfonic acids are the most interesting due to their greater acidity (pKa<0) potentially leading to applications.

Functionalized polyethylene containing precisely placed sulfonic acid groups synthesized via ADMET polymerization

246th National Meeting (2013)

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