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Integration of polycyclic aromatic hydrocarbon (PAH) units into semi-fluorinated polymers affords high thermal stability and excellent processability for potential applications in optoelectronic, gas-separation, and advanced composites. Base-promoted step-growth polycondensation of commercial bisphenols with new triphenylene containing bis-trifluorovinyl ether (TFVE) monomers affords semi-fluorinated arylene vinylene ether (FAVE) polymers in good yields. The solution-processable polymers form tough transparent films and produce substitution dependent blue-light emission in solution with emission quantum yields ranging from 7.2–12% (in dichloromethane). Although predominantly amorphous with high glass transition temperatures ( T g ) ranging from 176–243 °C, powder X-ray diffraction studies show typical molecular diameter and pi-stacking reflections for triphenylene polymers. The polymers exhibited excellent thermal stability, solution photostability, and remarkable thermal oxidative photostability after heating at 250 °C for 24 h in air. Further, a model post-polymerization Scholl coupling afforded a novel semi-fluorinated hexabenzocoronene polymer with new optical properties. Time-dependent density functional theory (TD-DFT) computations were also performed using SMD (dichloromethane)- ω B97XD/BS1 (BS1 = 6-31G(d′) for C, H, O and F). This work demonstrated the synthesis and characterization of processable, blue-light emitting, thermally stable triphenylene enchained semi-fluorinated aryl ether polymers.
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Teaching Old Polymers New Tricks: Improved Synthesis and Anomalous Crystallinity for a Lost Semi‐Fluorinated Polyaryl Ether via Interfacial Polymerization of Hexafluoroacetone Hydrate and Diphenyl Ether
Abstract A practical and direct electrophilic polymerization of hexafluoroacetone hydrate with diphenyl ether toward the preparation of semi‐fluorinated polyaryl ethers (PAE) is reported. Electrophilic aromatic substitution (EAS) polymerization under interfacial conditions with phase transfer catalyst (Aliquat 336) proceeds in trifluoromethanesulfonic anhydride by generation of trifluoromethanesulfonic acid and the protonated hexafluoroacetone (HFA) in situ affording 1,1,1,3,3,3‐hexafluoroisopropylidene (6F) PAE with high regioselectivity (4,4’‐DPE) and high molecular weight (≈60 kDa). Although first reported in a 1966 US Patent by DuPont using harsh conditions, improved synthetic methods or modern characterization has not been disclosed until now. Despite the presence of the 6F group, known to impart disordered morphology, this simple semi‐fluorinated PAE exhibits anomalous crystallinity with polymorphic melting points (Tm) ranging from 230–309 °C, high solubility in common organic solvents, a glass transition (Tg) of 163 °C, and thermo‐oxidative stability above 500 °C. Tough optically clear films prepared from solution give transmittance higher than 90% throughout the visible region. Synthesis, mechanistic aspects, and characterization including surface and dielectric properties are discussed.
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- Award ID(s):
- 2004133
- PAR ID:
- 10397932
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Macromolecular Rapid Communications
- Volume:
- 44
- Issue:
- 4
- ISSN:
- 1022-1336
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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