Tetraarylphosphonium perfluorocyclobutyl polyelectrolyte with low critical surface energy, high thermal stability, and high alkaline resistance

Abstract

Two tetraarylphosphonium polyelectrolytes having perfluorocyclobutyl units in their backbones have been prepared in which the counteranion is either bromide (PFP·Br) or bis(trifluoromethyl)sulfonimide (PFP·NTf2). These polymers exhibit high thermal stability as assessed by thermogravimetric analysis, with a decomposition temperature of 460 °C for PFP·NTf2. Even after heating at 300 °C for 72 h, PFP·NTf2 shows no signs of degradation detectable by nuclear magnetic resonance spectrometry. As is typical for many tetraarylphosphonium species, films of these polymers can be quite resistant to degradation by alkaline solution. Upon alkaline challenge by exposure to 6 M NaOH at 65 °C for 24 h, for example, only 16% of the phosphonium centers in PFP·NTf2 are degraded, making PFP·NTf2 one of the most alkaline‐stable phosphonium polymers to date. Despite having ionic backbones, PFP·Br and PFP·NTf2 exhibit very low critical surface energies of 26.1 and 22.9 mJ m−1, respectively. These values are on par with the values for poly(vinylene fluoride) and dimethylsiloxane. Such low surface energy polycations capable of high alkaline stability may find application as components of alkaline fuel cell membranes. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2267–2272

Low-Dielectric Polymers Derived From Biomass

“…Over the past few decades, researchers have developed a lot of low- k polymer materials, including epoxy resins, , polyimides, − cyanate ester resins, , benzoxazine resins, − benzocyclobutene resins, ,, and perfluorocyclobutyl-based resins. , However, most of those resins are produced through the petroleum-based feedstock, and the consumption of petroleum may lead the potential resource crisis. Therefore, developing the high-performance materials from renewable biomass to replace petroleum-based materials is very desirable. − Biobased feedstock can be easily prepared from nature, and it displays renewability, low pollution, and wide distribution .…”