J.E. McIntyre

Ionic conductivities of poly(methoxy polyethylene glycol monomethacrylate) complexes with LiSO3CH3

Abstract Ionic conductivity values for LiSO3CF3 complexes with two amorphous poly(methoxy polyethylene glycol monomethacrylates) (PEM) were determined and values as high as ∼6 × 10 −4 Ω −1 cm −1 at 373 K and ∼2 × 10 −5 Ω −1 cm −1 at 293 K were achieved. These values are compared with those obtained for a poly(ethylene oxide) (PEO)-LiSO3CF3 complex of similar salt concentration with an ether oxygen to Li+ ion ratio of 18. The conductivity results for the complexes are similar at temperatures >343 K but at 293 K the values for the conductivities of the PEM-LiSO3CF3 complexes are approximately two orders of magnitude higher than those for the PEO-LiSO3CF3 complex. This difference is believed to be due at least in part to the presence of a large amount of crystalline material in the PEO-LiSO3CF3 complex below 323 K.

Ionic conductivities for poly(ethylene oxide) complexes with lithium salts of monobasic and dibasic acids and blends of poly(ethylene oxide) with lithium salts of anionic polymers

Abstract Lithium salts of two polyanionic addition polymers containing alkyl sulphonic acid and perfluoroalkyl carboxylic acid side groups were prepared. Blends of these polymers were formed with poly(ethylene oxide) (PEO). The blend containing alkyl sulphonate units showed some phase separation but this was not observed for the blend containing perfluoroalkyl carboxylate groups. In the latter case a comparatively high conductivity of ∼10 −5 Ω −1 cm−1 at 374 K was obtained. The anionic units in these blends are expected to be virtually immobile. Complexes formed from PEO and the Li-salt of hexafluoroglutaric acid had similar high ionic conductivities and there are grounds for supposing that the anions in these complexes may also be substantially immobilized. In addition, conductivity values were obtained for some PEO complexes containing lithium salts of some monobasic acids and it was found that the complex formed from the Li-salt of the strongest acid gave the highest conductivity ( ∼4 × 10 −4 Ω −1 cm−1 at 373 K for a PEO-LiSO3CF3 complex).

Ionic conductivity and viscosity correlations in liquid electrolytes for incorporation into PVDF gel electrolytes

The correlation between ionic conductivity and viscosity in liquid electrolytes formed by the dissolution of lithium triflate in N,N-dimethyl formamide and tetraethylene glycol dimethyl ether has been investigated. These liquid electrolytes may be incorporated in polymer gel electrolytes based on poly(vinylidene fluoride). The use of the Walden product to investigate ionic interactions is discussed.

Polybiguanides: synthesis and characterization of polybiguanides containing hexamethylene groups

Abstract A series of polymeric biguanide hydrochlorides containing hexamethylene groups has been synthesized by developing methods for melt and solution polymerization, based on the reaction of cyano groups with amine hydrochlorides. These polymers were characterized by solution viscometry, gel permeation chromatography, 1H n.m.r. and i.r. spectroscopy and thermal analyses (d.s.c. and t.g.a.). The presence of some melamine groups in the polymers made by melt polymerization was noticed and identified based on i.r. spectroscopy. The polymer salts obtained were generally hygroscopic and water soluble and lacked crystallinity. The hygroscopicity of the polymers varied with the hydrocarbon groups contained in the chains and the extent and nature of salt formation. The polybiguanide salts in both aqueous and polar non-aqueous solutions showed typical solution viscosity features of polyelectrolytes. The polybiguanides readily formed coloured complexes with copper ions.

Thermotropic polyesters: fibres and mouldings from poly(chloro-1,4-phenylene terephthalate-co-4,4′-oxybisbenzoate)s

Abstract Fibres melt-spun from nematic mesophases of poly(chloro-1,4-phenylene terephthalate- co -4,4′-oxybisbenzoate)s ( 50 50 and 60 40 ) contain ordered crystalline regions and are highly oriented. Although heat treatments of the ‘as-made’ fibres do not affect their orientation or crystallinity, they result in increased tensile strength and extension at break. These improvements in tensile properties are ascribed to a rise of the molecular weight due to a solid-phase post-polycondensation. Mouldings produced from the 50 50 copolymer exhibit distinct anisotropy with a complex distribution of molecular orientation. Their tensile modulus in the flow direction is satisfactory at room temperature (∼ 13 GPa), but at elevated temperatures there is a pronounced drop in stiffness due to a loss process associated with the glass transition.

Thermotropic polyesters: Synthesis and properties of poly(chloro-1,4-phenylene terephthalate-co-4,4′-oxybisbenzoate)s

Abstract Poly(chloro-1,4-phenylene terephthalate), poly(chloro-1,4-phenylene 4,4′-oxybisbenzoate), and their copolymers are synthesized and the effect of composition on thermal transitions is evaluated. All the materials are nematogenic; copolymer compositions from 75 25 to 25 75 display a nematic temperature range in excess of 100°C which is sufficient for melt processing. The crystal-nematic transition temperature of the 50 50 copolymer is strongly affected by the molecular weight, but the glass transition, although low, is molecular weight independent. Brief annealing at temperatures below the crystal-nematic transition does not reduce the nematic temperature range of this copolymer.

Thermotropic polyesters: controlled decomposition of poly(1,4-phenylene terephthalate-co-t-butyl-1,4-phenylene terephthalate)

Abstract The elimination of t-butyl substituents from poly(1,4-phenylene terephthalate-co-t-butyl-1,4-phenylene terephthalate) and from a model compound, t-butylhydroquinone dibenzoate, was investigated. Thin-layer chromatography showed that the t-butyl groups could be thermally eliminated from the model compound at 320°C or at lower temperatures using Friedel-Crafts catalysts. The t-butyl substituents were not found to be removable from the polymer by thermal means, but the cleavage was achieved under the influence of trifluoromethanesulphonic acid, for which the best treatment temperature was below 25°C. Side reactions were also detected.

Ionic conduction in sequentially ordered thermotropic liquid-crystalline polymers

Abstract Main-chain liquid-crystalline polymers containing triad aromatic ester mesogenic blocks together with flexible ion-complexing oligo-oxyethylene blocks have been synthesized. A range of polyoxyethylene precursor polymers was employed with two different triad units to produce mechanically robust polymers exhibiting liquid-crystalline behaviour in the general range 100–200°C. Films were formed consisting of complexes with lithium trifluoromethane sulphonate. Useful ionic conductivities were obtained.

Factors affecting the formation of high molecular weight aromatic polyesteramides by solution polycondensation

Abstract Fully aromatic polyesteramides from aminophenols and benzenedicarbonyl chlorides are synthesized by low temperature solution polycondensation. The optimum conditions for the polycondensation reaction are established through systematic study of the factors affecting the molecular weight of the resulting polymers, which are reaction temperature, LiCl concentration, nature and concentration of the tertiary amine catalyst, water content in the solvent, concentration of the monomers, nature of solvent, rate of stirring and state of the acid chloride added.

Thermotropic polyesters: synthesis and properties of highly disordered copolymers

Abstract Sixteen nematogenic copolyesters were synthesized from four to seven different aromatic reactants, with the objective of suppressing crystallization. The constituent units contained rod-like 1,4-phenylene and 4,4′-biphenylene groups, crankshaft 2,6-naphthylene group and rigid angular 1,3-phenylene group. Wide-angle X-ray diffraction, differential scanning calorimetry and hot-stage optical microscopy showed that five of the copolyesters could be classified as lacking three-dimensional order. Within the range of compositions studied, a large number of different units of different types is conducive to suppressing crystallization.