Azide–para-Fluoro Substitution on Polymers: Multipurpose Precursors for Efficient Sequential Postpolymerization Modification

Abstract

The 2,3,4,5,6-pentafluorobenzyl group has become a popular reactive functionality in polymer chemistry because of its high susceptibility to para-fluoro substitution with thiols. Herein, it is demonstrated postpolymerization that the para-fluoride can be substituted using sodium azide and that the resulting 4-azido-2,3,5,6tetrafluorobenzyl-functional polymers are versatile precursors for a multitude of onward modifications with click-like efficiencies. Quantitative azide−para-fluoro substitution was found for poly-(2,3,4,5,6-pentafluorobenzyl methacrylate) and the related Passerini ester−amide (meth)acrylic (co)polymers when heated in DMF with sodium azide to 80 °C for 60−90 min. Conversely, the azidation of poly(2,3,4,5,6-pentafluorostyrene) under similar conditions resulted in ∼90% substitution efficiency. Azidefunctional (co-)polymers were thermally stable below 100 °C and were subsequently modified with (i) four different alkynes (CuBr, triethylamine, DMF, 55 °C, overnight) to give 1,4-substituted 1,2,3-triazoles in >95% conversions; (ii) potassium thioacetate (DMF, RT, 15 min) with quantitative amidation to the acetanilide derivative; and (iii) DL-dithiothreitol (methanol/ DMF, RT, 90 min), resulting in complete reduction of the azides to primary amines, which were subsequently acylated with two different acyl chlorides. Products were characterized by 1 H NMR, 19 F NMR, Fourier transform infrared spectroscopies, and size exclusion chromatography. Given their adaptability, perfluorophenylazides have huge potential as multipurpose intermediates in polymer and materials chemistry.

Light-intensity switch enabled nonsynchronous growth of fluorinated raspberry-like nanoparticles

“…An advantage of PPFS is the ease in post-synthetic modication by nucleophilic aromatic substitution on the -C 6 F 5 group, facilitating the preparation of functional polymers. 53,54 In our studies, when RB particles were treated with 1,2-ethanedithiol, cross-linked colloids were generated without a clear morphological change (Fig. 5a and b).…”

“…1d, spheres of hydration diameter ¼ 90 AE 10 nm were obtained using strong-light irradiation. Similarly, when other ratios of [PFS]/[PDMA 54 -CTA] (from 100/1 to 500/1) were employed to provide copolymers of different lengths of the uorinated segment, only a spherical morphology was observed (diameter ¼ 83 to 119 nm, M p ¼ 24.3-123 kDa, Fig. S6, S7 and Table S4 †), which is different from the morphology evolution trend detected in other photo-PISA processes.…”

“…At the beginning of our study, poly(dimethylacrylamide) (PDMA 54 , M n ¼ 5.64 Â 10 3 Da, Đ ¼ 1.06) terminated with a trithiocarbonate group was prepared as a chain-transfer agent (CTA), and employed in the photo-RDRP of PFS using tris(2phenylpyridine)iridium as a photocatalyst (PC) ([PFS]/ [PDMA 54 -CTA]/[PC] ¼ 300/1/0.1) under visible-light irradiation (400-750 nm, Fig. S1 †) at room temperature.…”

Fluorinated Polymers via Para‐Fluoro‐Thiol and Thiol‐Bromo Click Step Growth Polymerization

“…[26] PFTR and thiolbromo reactions are both base-activated coupling reactions with triethylamine (TEA) and 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU) frequently employed to initiate the reaction. [26,[29][30][31] These two types of click reactions have been well investigated and reported for post-polymerization modification (PPM), [8,25,26,28,29,[31][32][33][34] yet only a handful of reports demonstrated the preparation of step-growth polymers. [35][36][37][38][39] The fluorinated poly (aryl thioester) structures obtained from PFTR have great potential due to their remarkable physical properties [39] such as high refractive index (RI) values, [29] and low optical loss.…”

A new cardo bisphenol monomer containing pendant azido group and the resulting aromatic polyesters

“…Polymers containing azido functionality either at the chain end(s) or as pendant groups have attracted a great deal of attention as azido group is capable of undergoing the celebrated CuAAC click reaction, thus allowing access to modified polymers . With regard to step‐growth polymers, both postfunctionalization and functional monomer approaches have been put to use to obtain a range of azido‐functionalized aliphatic and aromatic polymers.…”