End Group Functionality of 95–99%: Epoxide Functionalization of Polystyryl‐Lithium Evaluated via Solvent Gradient Interaction Chromatography. Issue 23 (17th August 2022)

• Record Type: Journal Article
• Authors: Dreier, Philip; Ahn, Junyoung; Chang, Taihyun; Frey, Holger
• Is Part Of: Macromolecular rapid communications. Volume 43:Issue 23(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-17
• Subjects: carbanionic polymerization -- chain end functionalizations -- epoxides -- polymer characterizations -- solvent gradient interaction chromatography; Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.202200560
• Languages: English
• ISSNs: 1022-1336

Abstract

Abstract: End group functionality is a key parameter of functional polymer chains. The end‐capping efficiency of living polystyryl lithium with various epoxides, namely ethylene oxide (EO), ethoxy ethyl glycidyl ether (EEGE) and isopropylidene glyceryl glycidyl ether (IGG), is investigated with solvent gradient interaction chromatography (SGIC). Generally, end‐capping efficiencies >95% are observed. Hydroxy functional polystyrene (PS–OH, PS–EEGE–OH, and PS–IGG–OH) with molar masses ranging from 13.8 to 15.0 kg mol −1 are obtained, with dispersities of 1.05–1.06. Deprotection of the acetal (PS–EEGE–OH) and ketal protective group (PS–IGG–OH) is investigated. Nearly quantitative deprotection (>99%) resulting in the corresponding multihydroxy functional PS (PS–(OH)2 and PS–(OH)3 ) are observed via SGIC. Esterification of PS–OH with succinic anhydride shows a conversion of 98% to the corresponding ester. A detailed picture of side reactions during the carbanionic polymer synthesis subsequent epoxide termination is obtained, demonstrating 95–99% terminal functionality. Depending on the polarity of the end group, an elution order of PS–OH < PS–(OH)2 < PS–(OH)3 < PS–COOH is obtained in SGIC. The study demonstrates both the analytical power of SGIC and the exceptionally high terminal functionalization efficiency of anionic polymerization methods. Abstract : End‐capping of living polystyryl lithium with a variety of epoxides is investigated via solvent gradient interaction chromatography. Depending on the epoxide structure, end‐capping efficiencies between 95% and 99% are observed, which are in pronounced contrast to previously reported terminal functionalities of merely 84–91% for the controlled radical techniques atom transfer radical polymerization and reversible addition‐fragmentation chain‐transfer polymerization.