Aryl Ether Polymers Research Articles

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

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

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

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.

Ring-Forming Polymerization toward Perfluorocyclobutyl and Ortho-Diynylarene-Derived Materials: From Synthesis to Practical Applications.

Many desirable characteristics of polymers arise from the method of polymerization and structural features of their repeat units, which typically are responsible for the polymer’s performance at the cost of processability. While linear alternatives are popular, polymers composed of cyclic repeat units across their backbones have generally been shown to exhibit higher optical transparency, lower water absorption, and higher glass transition temperatures. These specifically include polymers built with either substituted alicyclic structures or aromatic rings, or both. In this review article, we highlight two useful ring-forming polymer groups, perfluorocyclobutyl (PFCB) aryl ether polymers and ortho-diynylarene- (ODA) based thermosets, both demonstrating outstanding thermal stability, chemical resistance, mechanical integrity, and improved processability. Different synthetic routes (with emphasis on ring-forming polymerization) and properties for these polymers are discussed, followed by their relevant applications in a wide range of aspects.

Clickable perfluorocyclobutyl aryl ether polymers bearing azido groups: synthesis and post-functionalization

A novel class of clickable perfluorocyclobutyl (PFCB) aryl ether polymers containing azido groups (APFCB polymers) is reported. The thermal cyclopolymerization reaction of 2-methyl-1,4-bis(1,2,2-trifluorovinyloxy)benzene was first optimized by DSC, GPC and 19F NMR, and the matrix polymer (PFCB-Me) with high average molecular weights (Mw = 13.61 × 104 g/mol) and molecular weight distributions (Mw/Mn = 1.68) was obtained. Then, a series of APFCB polymers with tunable azido contents were successfully prepared from the PFCB-Me polymer by bromination and azidation. Post-functionalization of APFCB polymers with sulfonate functionality was accomplished by Cu(I)-catalyzed azide-alkyne cycloaddition click chemistry. The prepared polymers were characterized by FT-IR and NMR spectra, while the thermal properties and solubility were also investigated. The APFCB polymers exhibit glass transition temperatures in the range of 67 °C to 73 °C and good solubility in common organic solvents. This work suggests that the designed APFCB polymers may be a promising versatile platform for developing new functional PFCB aryl ether polymers.

A Molecular Approach to Control the Morphology and Properties for the Development of Highly Conductive and Stable Anion Exchange Membranes

Anion exchange membrane fuel cells (AEMFCs) have drawn growing interests in the past decade.The inexpensive non-platinum group metal (non-PGM) catalyst and faster oxygen reduction reactions (ORRs) kinetic at high pH are the potential driving force to develop AEM materials.Despite numerous studies, molecular design rules have not yet been fully elucidated for the development of highly conductive and alkaline stable AEMs. Polymer materials that can produce tunable nanoscale and well-developed micro-phase separated morphology hold great promises as highly conductive and alkaline stable AEMs.Understanding the relationship between the structure and electrical/physicochemical properties of the corresponding AEMs are critical to the rational design and development of AEMs.We report herein a systematic approach to develop highly conductive and alkaline stable anion exchange membranes based on the non-(aryl ether) polymer backbone grafted with the pendant quaternary ammonium as an ion-conducting head group and the alkyl chain as a hydrophobic spacer in different ways. The effects of structure on the properties of the corresponding AEMs such as morphology, ion conductivity, physicochemical properties, and fuel cell properties will be investigated in detail.

Semi–fluorinated arylene vinylene ether (FAVE) telechelic polymers from polycyclic aromatic hydrocarbon bisphenols and trifluorovinyl aryl ethers

Semi-fluorinated arylene vinylene ether (FAVE) telechelomers and their chain extended PFCB polymers were synthesized via base catalyzed step-growth polymerization of polycyclic aromatic hydrocarbon (PAH) bisphenols and commercially available 4,4ꞌ-bis(4-trifluorovinyloxy)biphenyl (TFVE-BP) monomer. Soluble polymers were obtained in good yield, gave transparent free-standing films, and were characterized by 19F NMR, TGA, DSC, GPC, water contact angle and AFM. Thermal analysis by differential scanning calorimetry (DSC) revealed Tg values ranging from 150 to 168 °C. The new polycyclic aromatic FAVE polymers possess intact trifluorovinyl ether (TFVE) end groups susceptible to thermal chain extension leading to perfluorocyclobutyl (PFCB) aryl ether polymers with Tg ranging from 149 to 174 °C. Semi-fluorinated telechelic polymers with controlled terminal and enchained unsaturation with latent crosslinking ability may find use in specialty applications such as photonics or gas separation technologies.

Evaluation of carboxylic, phosphonic, and sulfonic acid protogenic moieties on tunable poly(meta‐phenylene oxide) ionomer scaffolds

A tunable, meta-linked aryl ether polymer scaffold enables the introduction of various acid groups for a fundamental comparison of their contributions to proton conduction. Sulfonic acid-functionalized polymers offer the best proton conduction at low temperature and high relative humidity, while phosphonic acid-functionalized polymers outperform sulfonic and carboxylic acid-derived polymers at high temperature or low humidity. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Post-functionalization of perfluorocyclobutyl aryl ether polymers with a novel perfluorosulfonated side chain precursor

To develop a new approach to prepare sulfonated perfluorocylobutyl (PFCB) aryl ether polymers, post-functionalization of PFCB aryl ether polymers with a novel perfluorosulfonated side chain precursor was described in this study. The precursor was firstly designed and synthesized from 4-(2-bromo-1,1,2,2-tetrafluoroethoxy) phenol and hexafluorobenzene via nucleophilic substitution, followed by sulfinatodehalogenation and oxidation. Then a series of novel sulfonated PFCB aryl ether polymers (FS-PFCB-x) was successfully prepared from the precursor by a nucleophilic aromatic substitution reaction. The components of the precursor were investigated by fourier transform infrared spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and high resolution mass spectrometry. The chemical structures of FS-PFCB-x polymers were characterized by NMR spectroscopy. FS-PFCB-xx polymers exhibited good thermal stability with decomposition temperatures up to 200 °C, and good solubility in polar aprotic solvents as dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide.

Design and synthesis of reactive polymers containing perfluorocyclobutyl (PFCB) and hydroxyl moieties for post-functionalization of PFCB aryl ether polymers

A novel class of perfluorocyclobutyl (PFCB)-containing reactive polymer with adjustable phenolic hydroxyl contents (PFCB-OH-xx) has been developed. A serial of PFCB-OH-xx polymers with high molecular weights (Mw > 100,000) and narrow molecular weight distributions (Mw/Mn < 1.15), were facilely prepared from 2-methoxy-1,4-bis(trifluorovinyloxy)phenyl via thermal cyclopolymerization and demethylation reactions. The monomer and polymers were characterized by FT-IR and NMR spectra. PFCB-OH-xx polymers exhibit good thermal stability and excellent solubility in common organic solvents. Initial investigation of the use of PFCB-OH-xx polymers as precursors in post-functionalization of PFCB aryl ether polymers, was successfully accomplished by a nucleophilic ring-opening reaction between the phenolic hydroxyl groups and 1,3-propanesultone. The degree of functionalization can be readily controlled by adjusting the hydroxyl contents of PFCB-OH-xx polymers. This work demonstrates that the designed PFCB-OX-xx polymers could be a class of promising precursor for development of new functional PFCB aryl ether polymers.

Suzuki polycondensation and post-polymerization modification toward electro-optic perfluorocyclobutyl (PFCB) aryl ether polymers: Synthesis and characterization

Abstract Suzuki polycondensation (SPC) as an alternative strategy has been utilized for the first time to readily yield functional perfluorocyclobutyl (PFCB) aryl ether polymers, which are difficult to obtain via the traditional [2+2] thermal cyclopolymerization strategy. Using two reactive PFCB aryl ether molecules as monomers, the biphenyl PFCB aryl ether polymer without any functionality was first prepared and exhibited good thermal stability, up to 450 °C at 8% weight loss (N2). By choosing appropriate functional monomers, aldehyde-functionalized PFCB aryl ether polymer precursor was also successfully prepared. Post-polymerization modification of this polymer precursor via Knoevenagel condensation yielded three distinct PFCB aryl ether polymers containing thermally stable triarylamine-based electro-optic chromophores.

Triarylamine-enchained semifluorinated perfluorocycloalkenyl (PFCA) aryl ether polymers

A variety of perfluorocycloalkenyl (PFCA) aryl ether monomers and polymers with enchained triarylamine units were successfully synthesized, characterized and reported here. These polymers are highly thermally stable and show variable thermal properties. Successful conversion of the newly synthesized TAA enchained perfluorocyclopentenyl (PFCP) aryl ether polymers via formylation and EAS demonstrates the synthetic versatility of TAA moiety and provides an excellent option for application specific post polymerization reactions. The cross-linking behavior of PFCP aryl ether polymers was studied under different reaction conditions. The combination of processability, thermal stabilities, and tailorability makes these polymers suitable for a wide variety of applications including electro-optics, proton exchange membranes and super-hydrophobic applications.

Perfluorocyclohexenyl aryl ether polymers via polycondensation of decafluorocyclohexene with bisphenols

ABSTRACTA novel class of semifluorinated perfluorocyclohexenyl (PFCH) aryl ether homo/copolymers was successfully synthesized with high yield through the step‐growth polymerization of commercially available bisphenols and decafluorocyclohexene in the presence of a triethylamine base. The synthesized polymers exhibit variable thermal properties depending on the functional spacer group (R). PFCH aryl ether copolymers with random and alternating architectures were also prepared from versatile bis‐perfluorocyclohexenyl aryl ether monomers. The PFCH polymers show high thermal stabilities with a 5% decomposition temperature ranging from 359 to 444 °C in air and nitrogen atmosphere. These semifluorinated PFCH aromatic ether polymers contain intact enchained PFCH olefin moieties, making further reactions such as crosslinking and application specific functionalization possible. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 232–238

Optimized statically non‐wetting hydrophobic electrospun surface of perfluorocyclobutyl aryl ether polymer

AbstractA statically non‐wetting highly hydrophobic fibrous surface was generated from biphenyl perfluorocyclobutyl aryl ether polymer (BP‐PFCB) by electrospinning. The optimization of solution parameters, which include concentration of the solution and number‐average molecular weight of the polymer, was followed by optimization of the instrumental parameters, which include flow rate, inter‐electrode voltage and inter‐electrode distance. Varying these parameters resulted in different degrees of hydrophobicity on the generated surfaces. The degree of hydrophobicity was determined by measuring static water contact angles. The effects of these variations in electrospinning parameters on the thickness of the fibers constituting the surface were also observed. It was found that the hydrophobic nature of the electrospun fibrous surface of BP‐PFCB depended on two factors: fluorine concentration and thickness of the fibers. During the optimization of the parameters, three different morphological regimes, namely beads, beaded fibers and fibers, were observed. The fine tuning of electrospinning parameters eventually produced a statically non‐wetting, highly hydrophobic surface which predominantly consisted of an intricate network of nanoscale fibers. © 2013 Society of Chemical Industry

Bis-perfluorocycloalkenyl (PFCA) aryl ether monomers towards a versatile class of semi-fluorinated aryl ether polymers

Abstract A unique class of perfluorocycloalkenyl (PFCA) aryl ether monomers was synthesized from commercially available perfluorocycloalkenes (PFCAs) and bisphenols in good yields. This facile one pot reaction of perfluorocycloalkenes, namely, octafluorocyclopentene (OFCP), and decafluorocyclohexene (DFCH), with bisphenols occurs at room temperature via an addition–elimination reaction in the presence of a base. The synthesis of PFCA monomers and their condensation with bisphenols lead to perfluorocycloalkenyl (PFCA) aryl ether homopolymers and copolymers with random and/or alternating polymer architectures.

Ultra low dielectric, self-cleansing and highly oleophobic POSS-PFCP aryl ether polymer composites

Ultra low dielectric constant (k = 1.53) materials with self-cleansing properties were synthesized via incorporation of fluorodecyl-polyhedral oligomeric silsesquioxane (FD-POSS) into recently synthesized perfluorocyclopentenyl (PFCP) aryl ether polymers. Incorporation of fluorine rich, high free volume, and low surface energy POSS into a semifluorinated PFCP polymer matrix at various weight percentages resulted in a dramatic drop in dielectric constant, as well as a significant increase in hydrophobicity and oleophobicity of the system. These ultra-low dielectric self-cleansing materials (θtilt = 38°) were fabricated into electrospun mats from a solvent blend of fluorinated FD-POSS with PFCP polymers.

Statically non-wetting electrospun perfluorocyclobutyl (PFCB) aryl ether polymer doped with room temperature ionic liquid (RTIL)

A statically non-wetting, electrospun surface of non volatile room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate, (BMIM-PF6), hosted in a solution-processable, semi-fluorinated perfluorocyclobutyl (BP-PFCB) aryl ether polymer was successfully prepared by electrospinning and compared with a surface prepared by spin casting. The surface properties of undoped and BMIM-PF6 doped systems were analyzed by water contact angle (WCA) and atomic force microscopy (AFM). BMIM-PF6 doped BP-PFCB surfaces prepared by spin casting showed a WCA of 90° while non-woven electrospun surfaces with the same BMIM-PF6 concentration showed high degree of hydrophobicity with a WCA greater than 150°. Morphologies of the electrospun surfaces were characterized by scanning electron microscopy (SEM). The surface composition was analyzed by energy-dispersive X-ray spectroscopy (EDXS) and attenuated total reflectance infrared spectroscopy (ATR-IR). Thermal analysis of the electrospun, non-woven surfaces of the doped and the undoped system of BP-PFCB were done by TGA.

Perfluorinated polymer colloids: Controlling the size, shape, and surface charge

The first report of perfluorocyclobutyl (PFCB) aryl ether polymer colloids is presented herein. The biphenyl rings were post-functionalized with chlorosulfonic acid modification in the backbone of the perfluoropolymer, thereby changing the zeta potential (ζ) of the colloids across the pH range (2–12). Self-assembly of the colloids was observed by scanning electron microscopy (SEM) on four separate surfaces which led to different morphological changes for each surface; spherical on Al substrate, clover-like on Cr substrate, flower-like on carbon substrate, and “squalloid” on Si substrate.

Perfluorocyclopentenyl (PFCP) Aryl Ether Polymers via Polycondensation of Octafluorocyclopentene with Bisphenols

A unique class of aromatic ether polymers containing perfluorocyclopentenyl (PFCP) enchainment was prepared from the simple step growth polycondensation of commercial bisphenols and octafluorocyclopentene (OFCP) in the presence of triethylamine. Model studies indicate that the second addition/elimination on OFCP is fast and polycondensation results in linear homopolymers and copolymers without side products. The synthesis of bis(heptafluorocyclopentenyl) aryl ether monomers and their condensation with bisphenols further led to PFCP copolymers with alternating structures. This new class of semifluorinated polymers exhibit surprisingly high crystallinity in some cases and excellent thermal stability.

Facile one-pot synthesis and thermal cyclopolymerization of aryl bistrifluorovinyl ether monomers bearing reactive pendant groups

A diverse pool of aryl bistrifluorovinyl ether (BTFVE) compounds with reactive pendant groups were prepared in a facile, high yielding three step “one-pot” synthesis from commercial 4-bromo(trifluorovinyloxy)benzene. Monomers were confirmed from ATR–FTIR, 1H, 13C, and 19F NMR, and HRMS analysis. Aryl BTFVE compounds were thermally polymerized to afford perfluorocyclobutyl (PFCB) aryl ether polymers with high number–average molecular weight (Mn) for homopolymers (17,050–27,090) and copolymers with 4,4′-bis(trifluorovinyloxy)biphenyl monomers (27,860–56,500). The PFCB aryl ether homo- and copolymers collectively possess high thermal stability (>299 °C in N2) and are readily solution processable producing optically transparent films. The thermal polymerization was achieved and reactive moieties remained intact, aside from those functionalized with acrylates. In the case with acrylate functionalized polymers, orthogonal polymerization was achieved by first photopolymerizing the acrylates followed by thermal curing of the aryl trifluorovinyl ether endgroups. Preliminary results in this study produced the successful preparation of photodefinable PFCB aryl ether material. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1887–1893, 2010

Preparation of composite fluoropolymers with enhanced dewetting using fluorinated silsesquioxanes as drop-in modifiers

Composite fluoropolymers were prepared by solvent blending fluorinated POSS (F-POSS) with perfluorocyclobutyl (PFCB) aryl ether polymers. The semifluorinated PFCB aryl ether polymers were shown to be hydrophobic, but demonstrated complete wetting by hydrocarbon-based liquids. Upon the incorporation of F-POSS as a drop-in modifier at low weight percent loadings, the composite fluoropolymer spin cast films exhibited increased water in addition to hydrocarbon repellency as determined by contact angle analysis. Composite film surface characterization included SEM and AFM analyses which showed excellent F-POSS dispersion and increased surface roughness. Thermal properties of the blended films were analysed using DSC and this demonstrated that the incorporation of F-POSS did not affect the bulk matrix properties inherent of PFCB aryl ether polymers. This work demonstrated that optimized F-POSS PFCB aryl ether polymer blend formulations have potential use as hydro- and oleophobic materials for seals, fibers, and coatings.