Shaken Not Stirred: Perfluoropyridine-Polyalkylether Prepolymers

Abstract

The purpose of this work was to employ perfluoropolyalkylethers (PFPAEs) with perfluoropyridines (PFPs) to form telechelic oligomers for use in low-temperature materials. Since perfluoropyridines are very regioselective, various nucleophiles were utilized, starting with an arsenal of PFPAEs such as oligo(hexafluoropropylene oxide) methylene alcohol (Krytox Methylene alcohols), Mach I perfluoroether diol, and Fluorolink E10H. Each reaction was completely successful with PFP using bases such as sodium hydride or the preferred cesium carbonate. Various solvents could be utilized (tetrahydrofuran (THF) or acetonitrile), but dimethylformamide (DMF) was the favored option. Further exploration was accomplished with mechanochemical synthesis, and the majority of the reactions were shortened from their 48 to 72 h reactions to approximately 1 min in good to moderate yields. Finally, Fluorolink E10-H-based bis(perfluoropyridine)-PFPAE was then copolymerized with Bisphenol A, Bisphenol AF, 1,1,1-tris(4hydroxyphenyl) ethane, and PEG 2000 forming novel materials, which were further characterized with thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS).

Fluorinated Pyridine Aryl Ether Polymers with Defined Microstructures, Diverse Architectures, and Tunable Thermal Properties

“…At 45 and 65 °C, DMSO-soluble fractions before gelation showed calculated M n values of 8195 and 7600 g/mol, respectively, with a monomer conversion of 94% at both temperatures, albeit revealing competitive oversubstitution of the 2,6-TFP position of the TFP BPAF monomer producing a mild degree of cross-linking. These results are consistent with recent work whereby segmented TFP perfluoropolyalkylethers (PFPAEs) were used to prepare elastomers from a series of bisphenols at 65 °C under similar base-catalyzed additions . The upper temperature limit at 80 °C produced an entirely gelled, insoluble material within 5 min, and no measurable degree of conversion was obtained.…”

“…These results are consistent with recent work whereby segmented TFP perfluoropolyalkylethers (PFPAEs) were used to prepare elastomers from a series of bisphenols at 65 °C under similar base-catalyzed additions. 37 The upper temperature limit at 80 °C produced an entirely gelled, insoluble material within 5 min, and no measurable degree of conversion was obtained. Therefore, given the observations of the model reactions as well as soluble NMR fractions at higher temperatures, it is presumed that the gelation is a combination of physical and more likely covalent cross-linking due to oversubstitution of F 2,6 on the TFP.…”

2,3,5,6-Tetrafluoro-[N-(3-aminopropyl)-ε-caprolactam]-4-pyridine

“…These unique polymeric materials have shown marked improvement over conventional state-of-the-art polymers in terms of their processability, mechanical strength, and compatibility with hybrid composites while retaining high temperature resistance. More recently, PFP was used for the mechanochemical synthesis of perfluoropolyalkylether (PFPAE) oligomers, which expands its utility for solvent-free polymerizations [12]. As an extension of this work, we report the detailed synthesis and structural characterization of a 2,3,5,6tetrafluoro-[N-(3-aminopropyl)-ε-caprolactam]-4-pyridine (1), as a new type of monomer for SNAr polymerizations.…”

High-performance polyimine vitrimers from an aromatic bio-based scaffold

“…51–53 Additionally, the nucleophilic phenol can be leveraged to construct monomers of highly aromatic nature from the nucleophilic aromatic substitution (S N AR) of scaffolds such as trichlorotriazine (TCT) and perfluoropyridine (PFP), which have been demonstrated as valuable building blocks for polymer functionalization and high-performance materials. 54–59…”