Synthesis and surface properties of novel fluorinated polyurethane base on F‐containing chain extender

A novel fluorinated chain extender, (1‐(ethyl(2‐hydroxyethyl)amino)‐3‐ ((3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctyl)oxy)propan‐2‐ol) (FPO), was synthesized and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and elemental analysis. Poly (ether urethane)s containing various amounts of the chain extender with fluorinated side chains (FPUs) were prepared by isophorone diisocyanate (IPDI), polytetra‐methylene‐ether‐glycol (PTMG), 3‐aminopropyltriethoxysilane (KH‐550), and 1,4‐butandiol (BDO). Films of FPUs were investigated by water absorption, contact angle, pencil hardness, adhesive force, and thermal analysis. Coating FPUs on micro‐nano concave‐convex structure plate realizes superhydrophobic performance. Scanning electron microscope (SEM) and atomic force microscopy (AFM) demonstrated that there is a lot of irregular concave‐convex structure, which forms a typical air cushion model. X‐ray photoelectron spectroscopy (XPS) analysis showed that surface fluorine content is 165% more than that of film average fluorine content. The superhydrophobic plate with 10% or higher F‐containing FPUs coating is of outstanding chemical corrosion resistance, excellent solvent resistance, and wear resistance.     

Preparation,characterization, and properties of fluorinated polyurethanes

Novel fluorinated polyurethanes (FPUs) were prepared by living radical polymerization of polyurethanes and hexafluorobutyl acrylate. The structures of the FPUs were characterized by FTIR, ¹H NMR, GPC, DSC, and XPS. The fluorinated polyurethane polymerization was investigated and showed monomer conversion, and molecular weight increased with increasing reaction time. In this way, the fluorine content in polyurethane could be easily adjusted by controlling the content of the fluorinated acrylate monomer. The mechanical evaluation shows that FPUs exhibit good mechanical properties. Morphology of FPU films was observed by scanning electron spectroscopy. The effects of the fluorine content on the surface properties and oxidative stability of FPUs were investigated. FPUs films were devoid of significant surface degradation after immersion in 20% H₂O₂ and 0.1 M CoCl₂ at 37 °C for 5 weeks. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3248–3256, 2009     

Preparation of an environmentally friendly antifouling degradable polyurethane coating material based on medium-length fluorinated diols

A novel medium-length fluorinated diols and poly(L-lactide) (PLLA) were synthesized via Michael addition reaction and ring-opening polymerization, respectively. Subsequently, Synthetic medium-length fluorinated diols and PLLA were combined to prepare new polyurethane composites with degradability and low surface energy. The compositional analysis and structural characterization of synthetic materials were characterized by using fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectra (¹HNMR). Thermogravimetric analysis(TGA) indicated that the introduction of medium-length fluorinated diols improved the thermal stability of the polyurethane. The biodegradation and low surface energy of the polyurethane were investigated by static hydrolysis experiment and water contact angle test. It was found that the degradation rate of the polyurethane increased as measurement time went on when the PLLA content was under 40%, and the water contact angle increased from 71.12° to 108.24° with the increase of fluorine content, which indicated that the degradable and low surface energy polyurethane has a potential as a coating material for a marine antifouling coating application.     

Angle‐resolved XPS of fluorinated and semi‐fluorinated side‐chain polymers

Angle‐resolved XPS data (elemental quantification and high‐energy‐resolution C 1s) are presented for ten polymers with side‐chains of the form ? OCO(CF₂)_yF, ? COO(CH₂)₂OCO(CF₂)_yF (y = 1, 2, 3) and ? COO(CH₂)_x(CF₂)_yF (x = 1, y = 1, 2, 3; x = 2, y = 8). Particular attention was paid to charge compensation and speed of data acquisition, with co‐addition from multiple fresh samples to give spectra with good energy resolution and good signal‐to‐noise ratio free from the effects of x‐ray‐induced degradation. Water contact angles for the polymers are also reported. The XPS data demonstrate preferential surface segregation of fluorine‐containing groups for all but the shortest side‐chain polymer, where the ? OCOCF₃ side‐chain either does not surface segregate or is too short for surface segregation to be detectable by angle‐resolved XPS. In the other polymers studied the relative positions of functional groups in the side‐chains correlate with the angle‐resolved behaviour of the corresponding C 1s components. This shows that the surface side‐chains are oriented towards the polymer surface. For the ? COO(CH₂)₂OCO(CF₂)_yF (y = 1) side‐chain, the angle‐resolved C 1s data suggest reduced ordering and linearity compared with y = 2 and 3. For any particular series of polymers, e.g. ? COO(CH₂)_x(CF₂)_yF, the water contact angles increase with y, consistent with burying of the hydrophilic ester groups as y increases. For any particular value of y the sequence of water contact angles is ? COO(CH₂)_x(CF₂)_yF > ? OCO(CF₂)_yF ～ ? COO(CH₂)₂OCO(CF₂)_yF, suggesting greater ordering and density of fluorocarbon species at the surface of the ? COO(CH₂)_x(CF₂)_yF side‐chain polymers compared with the other polymers studied. For the ? COO(CH₂)₂(CF₂)₈F polymer a water contact angle of 124° is measured, which is greater than that of poly(tetrafluoroethene). The ? COO(CH₂)₂OCO(CF₂)F polymer is unusual in that it shows a particularly low water contact angle (83° ), suggesting that the probe fluid is able to sense both ester groups, consistent with the reduced ordering of the side‐chain detected by angle‐resolved XPS. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis,surface property,micellization and pH responsivity of fluorinated gradient copolymers

In this work, fluorinated nonamphiphilic gradient copolymers of tert‐butyl acrylate (tBA) and 2,2,3,3,4,4,4‐heptafluorobutyl methacrylate (HFBMA) [poly(tBA‐grad‐HFBMA)] were first synthesized by semibatch atom transfer radical copolymerization of tBA and HFBMA. Their hydrolysis at acidic conditions led to amphiphilic poly(acrylic acid‐grad‐HFBMA). The chemical compositions and structures of these copolymers were characterized by proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography. Their surface properties were evaluated with water contact angle measurement and x‐ray photoelectron spectroscopy. The micellization behaviors of amphiphilic copolymer were also studied by transmission electron microscopy and dynamic light scattering. The results showed that the fluorinated and amphiphilic gradient copolymers could self‐assemble in a dilute solution to form aggregates of morphologies. Furthermore, the effect of pH on the aggregates was investigated to verify that the resulting gradient copolymers were to some extent pH sensitive. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and properties of fluorine-containing polyurethane based on long chain fluorinated polyacrylate

For the first time, a novel fluorine-containing polyurethane (FPU) was prepared by introducing long chain fluorinated polyacrylate into PU. The FPU was prepared from dodecafluoroheptyl methacrylate (DFMA), β-mercaptoethanol (β-ME), methacryloyloxyethyl isocyanate(MOI), hydroxyethyl methylacrylate (HEMA), iso-butyl acrylate(I-BA), polyether diol (N220) and toluene diisocyanate (TDI). The structure of product for every step was confirmed by Fourier transform infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance (¹H-NMR) spectra. It was found that when the DFMA content increased from 0 to 12%, thermal stability was improved in some degree; the hardness, the adhesion and the tensile strength increased; the swelling degree in water, NaOH solution and HCl solution decreased; the solvent resistance in hexane and butanone improved to some degree; the contact angle of water and ethylene glycol increased; the surface free energy decreased. XPS tests indicated fluorine migrated to surface.     

Miscibility and surface properties of fluorinated copolymer blends involving hydrogen‐bonding interactions

The miscibility and underlying hydrogen‐bonding interactions of blends of a fluorinated copolymer containing pyridine and a nonfluorinated copolymer containing methacrylic acid were studied with differential scanning calorimetry (DSC), transmission Fourier transform infrared (TX‐FTIR) spectroscopy, and X‐ray photoelectron spectroscopy (XPS), whereas the surface properties of the blends were investigated with contact‐angle measurements, time‐of‐flight secondary‐ion mass spectroscopy, XPS, and attenuated total reflectance Fourier transform infrared spectroscopy. DSC studies showed that the presence of a sufficient amount of 4‐vinylpyridine units in the fluorinated copolymer produced miscible blends with the nonfluorinated copolymer containing methacrylic acid. TX‐FTIR and XPS showed the existence of pyridine–acid interpolymer hydrogen‐bonding interactions. Even though the anchoring effect of hydrogen bonding hindered the migration of the fluorinated component to the blend surface, it could not completely eliminate the surface enrichment of the fluorinated component and the surface rearrangement of the fluorinated pendant chain. The air–blend interface was mainly occupied by the fluorinated pendant chain, and the surface energies of the blends were extremely low, even with only 1.5 wt % of the fluorinated component in the blends. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1145–1154, 2004     

Preparation and properties of well‐defined waterborne polyurethaneurea with fluorinated siloxane units in hard or soft segments

Two series of well‐defined polyurethaneurea (PUU) aqueous dispersions consisting of fluorinated siloxane units in the hard and the soft segments, respectively, were prepared from polyester polyol, α,ω‐dihydroxypoly[(3,3,3‐trifluoropropyl) methylsiloxane] (PTFPMS), dimethylolpropionic acid, isophorone diisocyanate, and ethylenediamine. These anionic aqueous dispersions were stable at the ambient temperature for more than 6 months. The experimental results showed that the water‐resistance performance of the PUU films prepared with the insertion of PTFPMS units into the hard segments (HFS series) were better than those prepared with the insertion of PTFPMS units into the soft segments (SFS series). The film prepared from the PUU aqueous dispersion incorporating 5 wt % PTFPMS in the hard segments exhibited the lowest water absorption amount (2.3 wt %) with the contact angle of water on the film surface greater than 90°. In comparison with the PUU film without adding PTFPMS, the waterproof performance and the mechanical properties of both HFS and SFS series were enhanced markedly. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5005–5016, 2007     

Synthesis and characterization of novel fluorinated polyimides derived from 4,4′‐[2,2,2‐trifluoro‐1‐(3‐trifluoromethylphenyl)ethylidene]diphthalic anhydride and aromatic diamines

A novel fluorinated aromatic dianhydride, 4,4′‐[2,2,2‐trifluoro‐1‐(3‐trifluoromethyl‐phenyl)ethylidene]diphthalic anhydride (TFDA) was synthesized by coupling of 3′‐trifluoromethyl‐2,2,2‐trifluoroacetophenone with o‐xylene under the catalysis of trifluoromethanesulfonic acid, followed by oxidation of KMnO₄ and dehydration. A series of fluorinated aromatic polyimides derived from the novel fluorinated aromatic dianhydride TFDA with various aromatic diamines, such as p‐phenylenediamine (p‐PDA), 4,4′‐oxydianiline (ODA), 1,4‐bis(4‐aminophenoxy)benzene (p‐APB), 1,3‐bis(4‐amino‐phenoxy)benzene (m‐APB), 4‐(4‐aminophenoxy)‐3‐trifluoromethylphenylamine (3FODA) and 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene (6FAPB), were prepared by polycondensation procedure. All the fluorinated polyimides were soluble in many polar organic solvents such as NMP, DMAc, DMF, and m‐cresol, as well as some of low boiling point organic solvents such as CHCl₃, THF, and acetone. Homogeneous and stable polyimide solutions with solid content as high as 35–40 wt % could be achieved, which were prepared by strong and flexible polyimide films or coatings. The polymer films have good thermal stability with the glass transition temperature of 232–322 °C, the temperature at 5% weight loss of 500–530 °C in nitrogen, and have outstanding mechanical properties with the tensile strengths of 80.5–133.2 MPa as well as elongations at breakage of 7.1–12.6%. It was also found that the polyimide films derived from TFDA and fluorinated aromatic diamines possess low dielectric constants of 2.75–3.02, a low dissipation factor in the range of 1.27–4.50 × 10^?3, and low moisture absorptions <1.3%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4143–4152, 2004     

Synthesis of crosslinkable fluorinated polyesters for optical waveguide devices

A series of novel crosslinkable, highly fluorinated polyesters were synthesized by copolycondensation reactions of terephthaloyl chloride with 4, 4′‐(hexafluoroisopropy‐lidene)‐diphenol and 2,2,3,3,4,4,5,5,6,6,7,7‐dodecafluoro‐octane‐1,8‐diol, followed by reaction with 2‐hydroxyethyl methacrylate. The resulting polyesters with the molecular weights (M_n: 12,100–20,000 g mol^?1) and polydispersities (1.49–2.25) were useful for the fabrication of polymer optical devices because of their good solubility in common organic solvent and the processable flexibility. The ratios of the components of the polyesters were characterized by FTIR and NMR. The polyesters had high glass transition temperature (T_g,: up to 170 °C) and good thermal stabilities (T_d: up to 470 °C). The refractive index of the polyester film was tuned and controlled in the range of 1.447–1.576 at 1550 nm by monitoring the component fractions during the preparation procedures. Low‐loss optical waveguides were fabricated from the resulting polyesters and the propagation loss of the channel waveguides was measured to be around 0.56 dB/cm at 1550 nm. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5923–5931, 2007     

Novel Biomembrane‐Mimicking Polymer Surface with Environmental Responsiveness

Summary: In this article, we designed and synthesized novel segmented poly(carbonate urethane)s containing both hydrophobic fluorinated alkyl group and hydrophilic phosphatidylcholine polar head groups on the side chain. The contact angle measurement, XPS, together with ATR‐IR investigation indicated a reversible overturn of the phosphatidylcholine groups with the movement of the hydrophobic fluorinated alkyl groups when the samples were treated in dry air or water. The change in environment from air to water induced a reorganization of the surface in order to minimize the interfacial free energy, resulting in a macroscopic change of surface wettability. The good environmental responsiveness of such biomembrane‐mimicking films may find successful applications as biomaterials.

Environmentally responsive surface using FPCPCU50 as an example; FPCPCU50 coated on aligned carbon nanotube film and dried in vacuum at 50 °C for 7 h and sample c treated in hot water at 80 °C for 1 h.     

Pyrolysis study of fluorinated sol-gel silica

Fluorinated silica gels at various fluorine content were prepared via sol-gel by hydrolysis of 3,3,3-trifluoropropyltrimethoxysilane and tetraethoxysilane mixtures. The gels, of nominal stoichiometry Si(CH₂CH₂CF₃)_XO_(2-X/2)(X=0.1-1), were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS) and N₂ adsorption analysis. The thermal stability of the fluorinated samples was investigated by coupling thermogravimetric measurements with mass spectrometric and gas chromatographic analyses of the evolved gaseous species. The chemical reactions occurring in the gel matrices during heating were siloxane chain rearrangements involving condensation between residual hydroxyl and ethoxyl groups in the 100-350°C temperature range, whereas the thermal decomposition of the fluoroalkyl groups were observed at higher temperatures (450-600°C). The release of the fluoroalkyl moieties also involved C-F/Si-O bond exchanges inside the siloxane chains, with gas-phase evolution of different fluorinated silicon units. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dispersion of silica nanoparticles bearing perfluorohexyl units into fluorinated copolymers

This study aims at determining the compatibility behavior of nanoparticles surface with fluorinated matrices to obtain a homogenous dispersion and better composites properties. First, modified silica nanoparticles by C₆F₁₃I and C₆F₁₃‐C₂H₄‐SH led to various fluorinated silica of different massic concentrations and grafting rates. The dispersion of these nanoparticles (in 5 wt %) into molten poly(VDF‐co‐HFP) and poly(TFE‐co‐HFP) matrices were studied as well as the hydrophobic, mechanical, and thermal properties of both fluorinated copolymers and resulting composites. In both series, the storage modulus of nanocomposites increased while the melting (T_m) and decomposition (T_10%) temperatures varied with the polymer matrix. They increased for poly(VDF‐co‐HFP) composites (T_m= 134 to 144 °C and T_10%= 441 to 464 °C) but decreased for poly(TFE‐co‐HFP) nanocomposites (T_m= 276 to 268 °C and T_10%= 488 to 477 °C). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1512–1522     

Synthesis and characterization of novel fluorinated polyurethane elastomers based on 2,2‐bis[4‐(4‐amino‐2‐trifluoromehyloxyphenyl) phenyl]propane

2,2‐Bis[4‐(4‐amino‐2‐trifluoromehyloxyphenyl) phenyl]propane (BAFPP) was synthesized based on 2‐chlorobenzotrifluoride and bisphenol A and characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance. BAFPP was used as a chain extender to prepare a series of fluorine‐containing polyurethane elastomers (FPUEs) with different fluorine contents by changing the soft segments and isocyanate index (R). The FPUEs were investigated by water absorption, contact angle, X‐ray photoelectron spectroscopy, thermogravimetric analysis, and microscale combustion calorimetry. The results show that the FPUEs prepared from BAFPP were elastomers that have low surface tension, low water absorption, and good thermal stability. Furthermore, FPUEs also exhibit good flame resistance, and the peak heat release rate of FPUE based on BAFPP (282.9 W/g) is much lower than that of polyurethane elastomer without the F element (537.2 W/g). Copyright © 2011 John Wiley & Sons, Ltd.     

Emulsion copolymerization of fluorinated acrylate in the presence of a polymerizable emulsifier

An emulsifier-free fluorinated polyarcylate emulsion was synthesized by a seed emulsion polymerization method from methyl methacrylate (MMA), butyl acrylate (BA) and hexafluorobutyl methacrylate (HFMA) in the presence of a polymerizable emulsifier—ammonium allyloxtmethylate nonylphenol ethoxylates sulfate (DNS-86). Influences of the DNS-86 level on electrolyte stability of the emulsifier-free emulsion were discussed. In addition, the emulsion and the films were characterized by Fourier transformed infrared (FT-IR) spectrometry, nuclear magnetic resonance (¹H NMR) spectrometry, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), thermogravimetry (TG), and contact angle (CA) analysis, respectively. The FT-IR spectra and ¹H NMR spectrum showed that HFMA was effectively involved in the emulsion copolymerization and monomers formed the fluorine-containing acrylate copolymer. The resulted emulsion particles had a core–shell structure and a narrow particle size distribution. XPS and CA analysis revealed that a gradient concentration of fluorine existed along the depth profile of the fluorine-containing emulsion film. One side of the film was richer in fluorine and more hydrophobic than the other side. The film formed from the fluorine-containing emulsion showed higher thermal stability than that of the fluorine-free emulsion.     

Synthesis of new fluorinated aromatic poly (ether ketone amide)s containing cardo structures by a heterogeneous palladium‐catalyzed carbonylative polycondensation

New fluorinated aromatic poly (ether ketone amide)s containing cardo structures were prepared by a heterogeneous palladium‐catalyzed polycondensation of fluorinated aromatic diiodides with ether ketone units, aromatic diamines containing cardo groups, and CO. Polymerizations were conducted in N,N‐dimethylacetamide at 120°C using 6 mol% of magnetic nanoparticles‐supported bidentate phosphine palladium (II) complex [Fe₃O₄@SiO₂‐2P‐PdCl₂] as catalyst and 1,8‐diazabicyclo[5,4,0]‐7‐undecene as base and resulted in fluorinated cardo poly (ether ketone amide)s with inherent viscosities up to 0.75 dL/g. All the polymers were readily soluble in many organic solvents and could afford transparent, flexible, and strong films by solution casting. These polymers showed good thermal stability with the glass transition temperature of 237°C–258°C, the temperature at 5% weight loss of 462°C–477°C in nitrogen. These polymer films also exhibited good mechanical properties, excellent electrical and dielectric performance, and high optical transparency. The incorporation of bulky fluorinated groups and cardo structures into polymer backbone has played an important role in the improvement of solubility, dielectric performance, and optical properties. Importantly, the heterogeneous palladium catalyst can easily be recovered from the reaction mixture by simply applying an external magnet and recycled up to 7 times without significant loss of catalytic activity.     

Synthesis of fluorinated polybenzoxazoles with low dielectric constants

Two fluorinated aromatic bis(o‐aminophenol)s, 1,1‐bis(3′‐amino‐4′‐hydroxyphenyl)‐1‐(3′‐trifluoromethylphenyl)‐2,2,2‐trifluoroethane (6FAP) and 1,1‐bis(3′‐amino‐4′‐hydroxyphenyl)‐1‐(3′,5′‐ditrifluoromethylphenyl)‐2,2,2‐trifluoroethane (9FAP) were synthesized, which were allowed to polycondense with aromatic diacyl chlorides to afford the fluorinated aromatic polybenzoxazoles (PBOs) via a conventional two‐step procedure in which the low‐temperature solution polycondensation process was first performed to yield poly(o‐hydroxyamide)s (PHAs) followed by the thermal cyclodehydration to give the PBOs. Experimental results indicated that the PHAs had inherent viscosities in the range of 0.29–0.68 dL/g, showing excellent solubility in organic solvents. The PHAs could be thermally cyclodehydrated into the corresponding PBOs at 260–370 °C. The obtained PBOs exhibited enhanced glass‐transition temperature but decreased solubility with respect to the PHAs. The PBOs showed glass‐transition temperatures in the range of 315–337 °C and excellent thermal stabilities with 5% original weight‐loss temperatures (T₅) of >513 °C. Additionally, the PBO films had average refractive index of 1.5298–1.5656, birefringence of 0.0051–0.0092, and low dielectric constants of 2.57–2.70. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and characterization of block and random POSS/fluorinated PAES tricopolymers

Block and random polyhedral oligomeric silsesquioxane (POSS)/fluorinated poly aryl ether sulfone tricopolymers were synthesized using different synthetic strategies to investigate the effect of sequence distribution on their thermal, dielectric, and surface properties. Analyses indicated that all block and random copolymers showed similar growth tendency of water contact angles and T_g values, downward tendency of k values with increased content of POSS. The block copolymer displayed higher T_g values up to 187°C than random copolymers (173°C) under the same POSS molar percentage, which were highly related to their different sequence distribution. The dielectric constants of the tricopolymers were drastically reduced because of the presence of POSS and fluorine, and the dielectric constant could achieve as low as 2.71 (1 MHz). Besides, sequence distribution has no obvious influence on its surface properties and properties. Meanwhile, the yields of degradation residues of the tricopolymers were significantly improved by the ceramic formation from POSS moieties during thermal decomposition. Copyright © 2016 John Wiley & Sons, Ltd.     

Sorption of carbon dioxide in fluorinated poyimides

Sorption isotherms of CO₂ for ten fluorinated polyimides measured at 35°C and up to about 25 atm are analyzed according to the dual-mode sorption model. Sorption properties for these polyimides are compared with those for other glassy Polymers including unfluorinated polyimides. The glassy polymers with higher glass transition temperatures T_g tend to show greater CO₂ sorption. Introduction of a ? C (CF₃)₂? linkage into the repeat unit of the main chain increases the sorption by 20–80%. For glassy polymers, including the fluorinated and unfluorinated polyimides, the Langmuir affinity constant b and Henry's law solubility constant k_D are correlated with the content of functional (carbonyl or sulfonyl) groups [FG], and composite parameter reflecting the magnitude of both [FG] and free-space fraction V_F, respectively, with some exceptions. The Langmuir capacity constant C′_H is correlated with T_g, but there are two correlation lines; one for unfluorinated polyimides and a different one for other glassy polymers including fluorinated polyimides. The slope of the former group is smaller probably because of smaller differences in thermal probably because of smaller differences in thermal expansion coefficients in rubbery and glassy states. Most fluorinated polyimides show greater solubility of CO₂ than unfluorinated polyimides and other glassy polymers, because of their larger C′_H and k_D. © 1993 John Wiley & Sons, Inc.     

Poly(bis‐2,2,2‐trifluoroethoxymethyl oxetane): Multiple crystal phases,crystallization‐induced surface topological complexity and enhanced hydrophobicity

Semicrystalline poly(bis‐trifluoroethoxymethyl)oxetane, P(B‐3FOx), was prepared by cationic ring‐opening polymerization at ?5 °C with M_n up to 21 kDa. Differences in cooling rates from the melt have substantial effects on crystal phase, percent crystallinity, surface topography, and wetting behavior. DSC and WAXD show that cooling from the melt at slow rates (<5 °C/min) gives α‐P(B‐3FOx) with ΔH_f = 22–27 J/g. Quenching from the melt results in β‐P(B‐3FOx) for which a mesophase structure is suggested. β‐P(B‐3FOx) melts at 53 °C followed by recrystallization to α‐P(B‐3FOx). Solution casting from THF results in third phase, γ‐P(B‐3FOx). TM‐AFM and SEM imaging for α‐P(B‐3FOx) showed that cold crystallization at 25 °C brought about increased crystallinity and surface topologies characterized by sharp asperities and lath‐shaped crystals. Spontaneous surface roughening of α‐P(B‐3FOx) results in a discontinuous three‐phase contact line with water and an increase in water sessile drop contact angle from 106° to 136°. The ～30° increase in water contact angle was attributed primarily to a topological change from a relatively smooth surface (Wenzel state) to an asperity‐rich surface yielding a discontinuous three‐phase contact line (composite of Wenzel and Cassie‐Baxter state). The oleophobicity for this polymer, which contains only a single ? CF₃ end group on each side chain, compares favorably with more highly fluorinated acrylates. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1022–1034, 2010