Dynamic mechanical behavior of poly(ether ether ketone)/poly(ether sulfone) block copolymers

Poly(ether ether ketone) (PEEK)/poly(ether sulfone) (PES) block copolymers were synthesized via condensation reaction between fluorine-terminated PEEK oligomers and hydroxyl-terminated PES oligomers. The dynamic mechanical behavior of a composite sample prepared by compression molding of a glass fibre cloth and the copolymer was investigated by means of a dynamic viscoelastometer. The β relaxation peak and the α′ relaxation peak were observed in the logarithmic decrement curve of the amorphous block copolymer of PEEK/PES. The glass transition temperature (β relaxation peak) is shifted to higher temperature and approaches a constant value as annealing time and degree of crystallinity increase. The glass transition temperature of the copolymer rises more slowly upon annealing with increasing PES content. The α′ relaxation peak becomes smaller upon annealing, and eventually disappears. The α′ relaxation peaks are related to the motion of molecules upon transition from the non-crystalline to the crystalline state. The α′ relaxation occurs for the copolymer with a degree of crystallinity of 0 to 3%.     

The crystal structure and drawing-induced polymorphism in poly(aryl ether ketone)s, 2. Poly(ether ether ketone ketone), PEEKK

The crystal structure, morphology and polymorphism induced by uniaxial drawing of poly(ether ether ketone ketone) [PEEKK] have been studied by transmission electron microscopy (TEM), electron diffraction (ED) and wide angle X-ray diffraction (WAXD). On the basis of WAXD and ED patterns, the crystal structure of unoriented PEEKK is determined to have two-chain orthorhombic packing with unit cell parameters of a = 0.772 nm, b = 0.600 nm, c = 1.004 nm (form I). A stress-induced crystal modification (form II) is identified and found to possess a two-chain orthorhombic lattice with unit cell dimensions of a = 0.461 nm, b = 1.074 nm, c = 1.080 nm. The 7.5% increase in c-axis dimension for form II is attributed to an overextended chain conformation, arising from extensional deformation during uniaxial drawing and fixed “in-situ” through strain-induced crystallization. The average ether-ketone bridge bond angles in form II crystal are determined to be 148.9° by using standard bond lengths. The crystal morphology of PEEKK bears a great similarity to that of PEEK. The crystals grow in the form of spherulites and have the b-axis of unit cell radial. The effects of draw rate on strain-induced crystallization and induction of form II structure are also discussed.     

Analysis and characterization of unusual ternary polymer miscibility in poly(ether diphenyl ether ketone), poly(ether ether ketone), and poly(ether imide)

A rare case of ternary polymer miscibility has been demonstrated in the mixture (in the glassy amorphous domains) comprising three polymers: polyetherimide (PEI), a new semicrystalline meta‐linked poly(ether diphenyl ether ketone) (PEDEKm), and semicrystalline poly(ether ether ketone) (PEEK). The T_g‐composition relationship for the ternary miscible blend system was treated by extension of the conventional models. The narrow T_g breadth also suggests that the scale of mixing was fine. The ternary blend exhibit no cloud point transition within the wide temperature range (50–400°C) studied. The interactions between any pairs among the three polymers were estimated using the Flory‐Huggins theory. The FT‐IR result gave further evidence that no significant specific interactions existed in any of the three binary pairs. The results collectively supported that no significant binary Δχ existed in the ternary polymer blend, which is favorable for leading this rare ternary miscibility.     

Block copolymers from isobutyl vinyl ether and 2-chloroethyl vinyl ether

Scope and limitation of the vinyl ether block copolymerization of isobutyl vinyl ether (IBVE) and 2-chloroethyl vinyl ether (CEVE) initiated by CH₃CHIOR/ZnI₂ were studied. These polymerizations exhibit the characteristics of a living polymerization. Di- and triblock copolymers were synthesized by sequential monomer addition (IBVE, CEVE). The poly(2-chloroethyl vinyl ether) (PCEVE) segment in those block copolymers is of particular interest because of the possibility to modify this segment by nucleophilic substitution of the chlorine. This strategy allows the synthesis of tailor made amphiphilic block copolymers.     

Thermal properties and crystallization behavior of poly(ether ether ketone ketone)/poly(ether biphenyl ether ketone ketone) copolymers

Thermal properties of poly(ether ether ketone ketone) (PEEKK)/poly(ether biphenyl ether ketone ketone) (PEDEKK) copolymers were investigated by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The glass transition temperature (T_g) increases from 154°C to 183°C as the content of PEDEKK units increases. The melting point (T_m) of the copolymers varied in the range between 314°C and 409°C and showed the behavior of eutectic type copolymer. From the investigation of the crystallization behavior of the copolymers, it was found that the cold-crystallization temperature (T_c′) of the amorphous copolymers assumes a maximum value for the copolymer with a mole fraction of the PEDEKK segment (n_B) of about 0.6, isothermally crystallized PEEKK and the PEEKK/PEDEKK copolymer exhibit double-melting behavior.     

Cation-binding ability of tactic poly(crown ether)s

Cation-binding ability of tactic poly(crown ether)s was evaluated by solvent extraction of alkali metal picrates. It was found that isotactic poly(crown ether)s bind particular cations, which can be easily sandwiched by two neighboring crown ether units, a little more effectively than syndiotactic ones. No difference of cation-binding ability was, however, observed between the corresponding d,l- and meso-bis(crown ether)s. This suggests that the rigidity of the poly(crown ether)s, in combination with the tactic configurations, causes the difference in the cation-binding ability.     

Sodium sulfonate-functionalized poly(ether ether ketone)s

A new monomer, sodium 5,5′-carbonylbis(2-fluorobenzenesulfonate) ( 1 ), was synthesized by sulfonation of 4,4′-difluorobenzophenone ( 2 ) with fuming sulfuric acid. Poly(ether ether ketone)s containing sodium sulfonate groups were synthesized directly via aromatic nucleophilic substitution from the sodium sulfonate-functionalized monomer 1 and Bisphenol A ( 3 ) in the presence of potassium carbonate in dimethyl sulfoxide. The polycondensation proceeds without any side reactions. The differential scanning calorimetry measurement indicated that the polymers are amorphous and the glass transition temperatures increase with the content of sodium sulfonate groups in the polymer chain. The degree of substitution with sodium sulfonate groups has strong influence on their thermal stability and solubility.     

Polymerizable monolayers derived from crown ether surfactants

Starting from dibenzo-18-crown-6, 1,10-diaza-18-crown-6 and 1,7-diaza-15-crown-5, several crown ether surfactants were synthesized. They all form stable monolayers on water. The methacryloyloxy derivative of 1,10-bis(3-dodecyloxy-2-hydroxypropyl)-1,10-diaza-18-crown-6, 2c , could be polymerized in the monolayer by UV irradiation. This polymerizable crown ether surfactant also forms synthetic vesicles by sonication in water.     

Concise synthesis and characterization of 30-membered macrocyclic monomer for poly(ether ether ketone)

A 30-membered macrocyclic arylene ether ketone monomer for poly(ether ether ketone) was synthesized by a two-step method. The first step involves synthesis of a long bisphenol from hydroquinone and 4,4′-difluorobenzophenone. The second step is the cyclization of the bisphenol with 4,4′-difluorobenzophenone. The pure macrocycle was isolated and characterized by IR, NMR, MS, TGA and DSC techniques. The X-ray structure of the macrocycle was also determined.     

Short latency induction of lordosis by ether in estrogen-primed female rats

Brief ether exposure induced high quality sexual receptivity in ovariectomized, estrogen-treated rats, presumably by increasing the secretion of adrenal progestins. Adrenalectomy completely blocked the effects of ether on this behavior. The onset of receptivity occurred 30--60 min following ether exposure; latencies much shorter than those previously reported necessary for adrenal mediation of female sexual behavior. The rapid onset and high quality of female behavior induced by adrenal secretions indicate that the adrenal glands can be sources of artifact when attempting to identify nonadrenal factors controlling receptivity.     

Living cationic polymerization of cyclohexyl vinyl ether

The cationic polymerization of cyclohexyl vinyl ether (CHVE) initiated by α-halogeno ethers in the presence of a Lewis acid activator has been investigated first. In conditions leading to a living polymerization of alkyl vinyl ethers (ethyl, isobutyl, etc.), an extremely fast polymerization, accompanied by chain transfer reactions, is observed with CHVE. In fact, we have shown that the polymerization of this monomer may be directly initiated by the HI and HCl adducts of CHVE, in the absence of any electrophilic activator. However, even in these conditions, the polymerization cannot be controlled. A “living” polymerization of CHVE was finally obtained by addition of ammonium salts (NBu₄X; X = Cl, Br, I) to the systems free of electrophilic activators. The added salts stabilize the α-halogeno ether chain ends and reduce the overall reactivity. Using this procedure, we have synthesized poly(CHVE)s with M?_n's ranging from 6 · 10³ to 4 · 10⁴ g · mol^?1 (in good agreement with the predicted values assuming the formation of one polymer chain per initiator molecule) and narrow molecular weight distributions (M?_w/M?_n < 1,2). Though most of poly(alkyl vinyl ether)s exhibit glass transition temperatures far below 0°C, the glass transition temperature of the poly(CHVE) is close to +50°C, indicating that this monomer can be used as a precursor to rigid poly(vinyl ether) blocks.     

Synthesis of amphiphilic block copolymers by polymer analogous modification of poly(2-chloroethyl vinyl ether)-block-poly(isobutyl vinyl ether)

Amphiphilic block copolymers were prepared starting from poly(2-chloroethyl vinyl ether)-block-poly(isobutyl vinyl ether) (PCEVE-b-PIBVE) via polymer analogous reaction. The chlorine function in the hydrophobic poly(2-chloroethyl vinyl ether) segment was substituted by polar groups to achieve block copolymers containing a hydrophilic poly(vinyl ether) segment. This procedure allows the synthesis of tailor made amphiphilic block copolymers.     

The solid state 13C NMR studies of intermolecular hydrogen bonding formation in a blend of phenolic resin and poly(hydroxyl ether) of bisphenol A

The formation of intermolecular hydrogen bonds in blends of novolac type phenolic and poly(hydroxyl ether) of bisphenol A was investigated by studying its T_g behavior, excess volume, and solid state ¹³C NMR spectra. The T_g and parameters of solid state ¹³C NMR, such as the T_CH and spin‐lattice relaxation time in the rotating frame T^H_1ρ, indicate that the London dispersion force (entropically favored) significantly affects the intermolecular hydrogen bonding of the blend. The phenoxy chain forces opening of the intra‐association of phenolic and thus creates more free OHs. This strong entropic effect reduces the total hydrogen bonding of the system, especially when one of the polymer is the minor component. This also results in the reduction of T_g and free volume expansion, reflecting in the increase of cross‐polarization (C—H) time and molecular mobility within the phenolic/phenoxy blend.     

Cytotoxicity of ester and ether lysophospholipids on Leishmania donovani promastigotes

The cytotoxic activity of four ester lysophospholipids, three ether lysophospholipids, and two radylglycerols on Leishmania donovani promastigotes was determined by measuring the inhibition of cell growth. The 1-acyl lysophospholipids reduced cell growth to 50% of controls at concentrations of 6.4-10.9 microM. In contrast, 1-O-alkenyl-sn-glycero-3-phosphoethanolamine, 1-O-hexadecyl-sn-glycero-3-phosphocholine, and 1-O-hexadecyl-sn-glycerol already showed a 50% inhibition of growth at concentrations between 2.1 and 2.8 microM. Moreover, the unnatural alkyl lysophospholipid analogue 1-O-octadecyl-2-methoxy-sn-glycero-3-phosphocholine was even 10-fold more toxic. Incubations of L. donovani promastigotes with radioactively labelled ether lysophospholipids revealed a rapid uptake of these compounds and their incorporation into cellular lipids at a non-toxic concentration of 1.0 microM. An accumulation of the lysophospholipids in the cell due to insufficient metabolism may be the cause of its cytotoxic effect. The sensitivity of L. donovani cells towards ether lysophospholipids was found to be similar to that reported for tumor cells.     

Effect of ether and Ca++ on infectivity of poliovirus RNA

Summary Using conventional procedures of extraction with diethyl ether to remove phenol, the infective poliovirus RNA titer was found to be 5 to 100 times greater when the virus stock was diluted about one-hundredfold into certain diluents prior to treatment with phenol (560 mM) than when undiluted stock was treated. Diluents giving this result were calcium-free, magnesium-free, mildly alkaline (pH 7–11) solutions, notably, e. g., 10 mM NaHCO₃. The milieu afforded by such diluents was not necessary for the treatment with phenol but was necessary primarily to prevent inactivation of the poliovirus RNA by the ether; however, even without exposure to ether and with no extractions to remove phenol, mildly acid conditions or a moderate concentration of Ca⁺⁺ resulted in some loss of infective RNA titer. Assay of ethereal phase detected no infectivity. Even with added base and chelating agent, extractions of phenol-treated essentially undiluted virus stocks with ether resulted in large loss of infective RNA titer. Extractions with benzene in place of ether had little or no effect on RNA titer using diluted systems; but with undiluted systems, a large titer loss was found. Treatment with ether without extractions with ether also inactivated RNA. Using heat shock (70° C, 20 seconds) in place of phenol to obtain infective RNA, the nature of the diluent required to give high infective RNA titer was very different from that required for the prephenol dilution when the conventional extractions with ether were employed.Aided by a grant from the National Foundation. Part of these results were presented on August 25, 1964, at a meeting of the Genetics Society of America at the University of Colorado, Boulder.     

A technique to anesthetize turtles with ether.

A technique to anesthetize turtles with ether is presented, in which a plastic cannula is passed through the glottis into the trachea. This procedure avoids apnea and allows ether vapours obtained from a chamber to be introduced, by the animal respiratory movements or by means of a pump, into the animal lungs. The anesthesia is rapidly obtained and lasts from 45-90 minutes. The time of recovery from anesthesia ranged from 60-90 minutes. With this technique no deaths were observed and the same animal could be anesthetized repeatedly.     

Crystallographic Equivalence of Ether and Ketone Groups in Poly(aryl ether ketone)s

Crystallographic equivalence of ether and ketone in all para‐substituted PAEKs crystallized in Form I was discussed in this paper. In a word, crystallographic equivalence between ether and ketone groups is tenable when the polymer contains only phenyl rings in the repeat unit. If the polymer contains a diphenyl group in the repeat unit, two cases should be distinguished. In the case of PEDEKK and PEEKDK, crystallographic equivalence between ether and ketone linkages is untenable. However, in the case of PEDK and PEDEKDK, crystallographic equivalence between ether and ketone linkages is still tenable.     

Solid state behaviour and properties of compression moulded poly(ether ether ketone)/polysulfone blends

Poly(ether ether ketone) (PEEK)/polysulfone (PSF) blends were obtained by kneading and compression moulding over the whole composition range. The blends were then both quenched and slowly cooled. Both cooling procedures provided blends with two practically pure phases and good small strain properties. Ductility was worsened, as expected, in slowly cooled blends. However, in quenched blends, which provided less phase-separated fracture surfaces and no very different free volume, ductility showed unexpected good values which are tentatively attributed to common features of the chemical structure of both blend components.     

NMR investigation of UV‐cured vinyl ether networks

The structure of the networks obtained by UV curing of the triethylene‐glycol divinyl ether (DVE3) and its mixtures with diethylene‐glycol monovinyl ether (HDVE2) was investigated by high resolution ¹H and ¹³C NMR spectroscopy. By working in swelled systems, signals with good resolution were obtained and were assigned to the different structures. The signals attributable to the CH₃ end groups of the poly(vinyl ether) together with the CH₂ and CH groups of the chain could be distinguished. The CH₃ groups signal is stronger in the case of the DVE3/HDVE2 mixture as a consequence of the chain transfer reaction. Hydrolysis reactions occur in the systems giving rise to the formation of acetaldehyde and aldehydic end groups.