SuFEx-Based Polysulfonate Formation from Ethenesulfonyl Fluoride-Amine Adducts

Abstract

The SuFEx-based polycondensation between bisalkylsulfonyl fluorides (AA monomers) and bisphenol bis(t-butyldimethylsilyl) ethers (BB monomers) using [Ph₃ P=N-PPh₃ ]⁺ [HF₂ ]^- as the catalyst is described. The AA monomers were prepared via the highly reliable Michael addition of ethenesulfonyl fluoride and amines/anilines while the BB monomers were obtained from silylation of bisphenols by t-butyldimethylsilyl chloride. With these reactions, a remarkable diversity of monomeric building blocks was achieved by exploiting readily available amines, anilines, and bisphenols as starting materials. The SuFEx-based polysulfonate formation reaction exhibited excellent efficiency and functional group tolerance, producing polysulfonates with a variety of side chain functionalities in >99 % conversion within 10 min to 1 h. When bearing an orthogonal group on the side chain, the polysulfonates can be further functionalized via click-chemistry-based post-polymerization modification.

Keywords: SuFEx reaction; bifluoride salt; click chemistry; ethenesulfonyl fluoride; polysulfonate formation.

Figure 1

Bifluoride promoted polysulfonate formation between bisalkylsulfonyl fluorides and bisphenol bis(t-butyldimethylsilyl) ethers.

Figure 2

Polysulfonate 8a formation under different catalytic conditions. a) Workup conditions: After the reaction went to completion, the solution was diluted with same volume of DMF followed by precipitation from methanol). b) No solid precipitation was observed after workup c) Catalyst loading was calculated based on the functional groups. d) M_n^ps values were M_n in reference to polystyrene standards.

Figure 3

Preparation of polysulfonate polymers from aniline ESF adducts 6 and bisphenol A bis(t-butyldimethylsilyl) ether 7a. a) The reactions were conducted with 0.5 mmol of each monomer for 10 min. b) The catalyst loading was calculated based on the functional groups. c) The products were isolated by precipitation from methanol and analyzed by Gel permeation chromatography (GPC). d) M_n^ps values were M_n in reference to polystyrene standards. e) M_n^MALLS values were determined by multi-angle laser light scattering. f) T_i = 5% weight loss temperature.

Figure 4

Preparation of polysulfonates from amine ESF adducts. a) The reactions were conducted with 0.5 mmol of each monomer. The catalyst loading was calculated based on the functional groups. The products were isolated by precipitation from methanol and analysed by GPC. M_n^ps values were in reference to polystyrene standards. b) T_i = 5% weight loss temperature.

Figure 5

Large scale synthesis of polysulfonate 8a.

Figure 6

Post-polymerization modification of polysulfonate 9a, 9b, and 9c.