SuFEx on the Surface: A Flexible Platform for Postpolymerization Modification of Polymer Brushes

Abstract

Polymer brushes present a unique architecture for tailoring surface functionalities due to their distinctive physicochemical properties. However, the polymerization chemistries used to grow brushes place limitations on the monomers that can be grown directly from the surface. Several forms of click chemistry have previously been used to modify polymer brushes by postpolymerization modification with high efficiency, however, it is usually difficult to include the unprotected moieties in the original monomer. We present the use of a new form of click chemistry known as SuFEx (sulfur(VI) fluoride exchange), which allows a silyl ether to be rapidly and quantitatively clicked to a polymer brush grown by free-radical polymerization containing native -SO2F groups with rapid pseudo-first-order rates as high as 0.04 s(-1). Furthermore, we demonstrate the use of SuFEx to facilely add a variety of other chemical functional groups to brush substrates that have highly useful and orthogonal reactivity, including alkynes, thiols, and dienes.

Multifunctional Surface Manipulation Using Orthogonal Click Chemistry

“…Each dye reaction was allowed to stir for 30 min due to the observed kinetics of the reaction of an aryl sulfonyl fluoride and an aryl TBDMS derivative, which has a pseudo-first-order rate (Figures 1A and 3), an order of magnitude slower than the k′ = 0.04 s −1 observed between alkyl sulfonyl fluorides and an alkyl TBDMS derivative in our previous work. 29 Although SPAAC (k′ = 0.0418 s −1 at 25°C ) and aminolysis (k′ = 0.2783 s −1 at 40°C) are faster reactions, to closely mimic the one-pot orthogonal reaction with the trireactive surface, each slide was placed in the respective dye solution for a full 30 min. Since sulfonyl fluorides are known to react with amines at raised temperatures, a PEFABLOC functionalized surface was immersed in an AMP/ TEA solution, where no functionalization with AMP was observed.…”

“…PFPA was synthesized following previously reported methods. 29 It was further purified using a plug of neutral alumina with DCM as eluent to remove any residual acrylic acid. The AIBN-silane initiator was also prepared using previously reported methods and, after synthesis, stored immediately in an inert atmosphere glovebox.…”

Selective and Orthogonal Post-Polymerization Modification using Sulfur(VI) Fluoride Exchange (SuFEx) and Copper-Catalyzed Azide–Alkyne Cycloaddition (CuAAC) Reactions

“…In this work, we exploited the exquisite reactivity of the sulfur(VI) fluoride moiety toward aryl silyl ethers, a facet of sulfur fluoride exchange (SuFEx) chemistry that was first reported by Gembus 19 and further developed by Sharpless and our laboratories eq 1 and 2. 20,21 SuFEx was also recently exploited for the postmodification of polymer brushes on surfaces, 22 work highly related and complementary to our own herein. The SuFEx reactions, in combination with CuAAC eq 3, provide a robust and modular platform for selective modification of polymers and/or other materials.…”

Multidimensional SuFEx Click Chemistry: Sequential Sulfur(VI) Fluoride Exchange Connections of Diverse Modules Launched From An SOF4 Hub

“…Key to SuFEx activation is the requirement for fluoride to transit from a strong covalent bond to a leaving group-a process mediated by 3° amine derived catalysts [8] and thought to involve bifluoride ion and related species. [7,[9][10][11][12][13] Early in the development of SuFEx, we identified sulfuryl fluoride (SO 2 F 2 ) [7,14] as a sulfur(VI) hub for creating diaryl sulfate links between molecules. Under SuFEx conditions the latent reactivity of the otherwise stable S VI -F bond is roused to react with SuFExable substrates.…”

“…Under SuFEx conditions the latent reactivity of the otherwise stable S VI -F bond is roused to react with SuFExable substrates. [7,15] While SuFEx is still an emerging technology it has already found diverse applications including, for example: the synthesis of tosylates [9] and sulfonyl azides;, [10] application in polymer chemistry [11] and post polymerization modification; [12,13] Suzuki coupling of aryl- and heteroaryl-fluorosulfates with boronic acids. [15] Of particular significance, however, is the potential for SuFEx in biochemical applications-we have growing evidence to believe that proteins provide molecular and dynamic electrostatic field environments that sulfur(VI) fluoride linkages are adept at reading and reacting to.…”