Triphenylene-Enchained Perfluorocyclobutyl Aryl Ether Polymers: A Modular Synthetic Route to Processable Thermoplastics Approaching Upper Limit T_g and Photostability

Abstract

Triphenylene-containing trifluorovinyl ether monomers prepared from 2,3-disubstituted-bis-1,4-(p-bromophenyl)triphenylene core building blocks undergo thermal step-growth polymerization (Ph 2 O, 180 °C), affording perfluorocyclobutyl polymers with unprecedented glass-transition temperatures (up to 295 °C), excellent high thermal-oxidative stabilities, and solution processability. The modular synthetic route provides access to a series of triphenylene monomers from a common cyclopentadienone derivative and variably substituted alkynes, which polymerize thermally to solution-processable, tough, transparent films with bright blue solid-state photoluminescence (λ em = ∼400−470 nm). Conversion was monitored by 19 F NMR end-group analysis and gel permeation chromatography to reasonably high molecular weights (M n = 45−93 kDa). Remarkably, photoemission persists at 250 °C in air for 24 h with negligible changes in absorbance and emission wavelengths after cooling to room temperature.

Triphenylene containing blue-light emitting semi-fluorinated aryl ether polymers with excellent thermal and photostability

“…† The HR-MS and ATR-FTIR values of intermediates 1-8 and monomers M1 and M2 were previously presented. 54 Base-mediated step-growth polymerization of M1 and M2 (Scheme 1) with commercially available bisphenol A or bisphenol AF produced triphenylene-enchained semi-fluorinated thermoplastic FAVE polymers P1-P4 (using NaH) and P1 0 -P4 0 (using Cs 2 CO 3 ) in 78-95% isolated yields after precipitation into CH 3 OH/H 2 O (50 : 50). The FAVE polymers each contain an all para-substituted pentaphenylene chain structure rarely reported within a soluble polymer.…”

“…The solid-state ATR-FTIR spectra of monomers M1 and M2 exhibited a small characteristic stretching band for the ArO-CFQCF 2 double bond at 1832 cm À1 . 51,54 The polymers P1-P4 and P1 0 -P4 0 were also characterized by ATR-FTIR experiments (Fig. S1 and S2, ESI †) which showed vibrations resembling: Ar/CQC stretching (1650-1500 cm À1 ), C-F stretching (1100-1000 cm À1 ), sp 2 C-O stretching (1350-1200 cm À1 ), and sp 3 C-O stretching (B1000-850 cm À1 ) bands.…”

“…[35][36][37] Unlike fully fluorinated or highly fluorinated polymers, semi-fluorinated polymers generally exhibit better solubility. 49 The enchainment of polycyclic aromatic hydrocarbon (PAH) units (such as hexabenzocoronene, 50 acenaphthenequinone, 51 phenanthrenequinone, 52,53 and triphenylene 54 ) afforded a new class of semi-fluorinated polymers for potential applications in optoelectronic, gas-separation, and advanced composites (Fig. 1).…”

“…Recently, our research group has reported triphenylene-enchained semi-fluorinated polymers as an extension to a general platform to combine property driving PAH core segments within robust and processable fluoropolymers. 54 Perfluorocyclobutyl (PFCB) aromatic ether polymers were obtained via [2+2] radical-mediated thermal cyclopolymerization of triphenylene-enchained monomers containing trifluorovinylether (TFVE) end groups (Fig. 1).…”

Renewable isosorbide‐enchained semi‐fluorinated aromatic ether polymers

“…Our research group has focused on the synthesis and applications of tailored semi‐fluorinated aromatic ether polymers prepared via step‐growth polymerization, as shown in Figure 1. The fluorinated linkages in polymer include perfluorocyclobutyl (PFCB), 8,9 perfluorocycloalkenyl (PFCA), 10 and fluorinated arylene vinylene ether (FAVE) 11 . Varying the spacer ‘R’ group shows tunability in the polymer properties for desired applications (Figure 1).…”