Phenothiaphosphine-containing polyamides and polyesters

Phosphorus-containing polyamides and polyesters, which had tricyclic fused rings (phenothia-phosphine rings) in the main chain, were prepared and the properties of the resulting polymers were examined. These polymers were obtained at highly reduced viscosities in satisfactory yields by the polycondensation of 2,8-dichloroformyl-10-phenylphenothiaphosphine 5,5,10-trioxide with aromatic diamines or bisphenols. The polyamides and polyesters were soluble in polar aprotic solvents such as dimethylacetamide and N-methyl-2-pyrrolidone; the polyesters were also soluble in chloroform. The polymers exhibited good heat resistance. The phenothiaphosphine-containing polyamides and polyesters self-extinguished immediately when flame was removed and were highly flame-resistant. The polyester obtained from bisphenol A showed a limiting oxygen index value of 43.5.     

Poly(1,3,4-oxadiazole-amide)s containing pendent imide groups

A series of new poly(1,3,4-oxadiazole-amide)s containing pendent imide groups has been synthesized by solution polycondensation of aromatic diamines containing preformed 1,3,4-oxadiazole rings with two diacid chlorides containing imide rings. These polymers were also prepared by the reaction of the same diacid chlorides with p-aminobenzhydrazide which were subsequently cyclodehydrated in solid state. The polymers were soluble in polar amidic solvents and some of them gave transparent flexible films by casting from solutions. They showed high thermal stability with decomposition temperatures above 400°C and glass transition temperatures in the range of 245–327°C. They had low dielectric constants, in the range of 3.32–3.94, and good tensile properties.     

Aromatic polymers with side oxadiazole rings as luminescent materials in LEDs

Aromatic polyamides and polyazomethines with side oxadiazole rings have been synthesized by using aromatic diamines containing pendent substituted oxadiazole groups and a diacid chloride having diphenylsilane or hexafluoroisopropylidene, or an aromatic dialdehyde with fluorene unit, respectively. These polymers were easily soluble in amidic solvents. Very thin films which were deposited from polymer solutions onto silicon wafers exhibited smooth, pinhole-free surface in atomic force microscopy investigations. The polymers showed high thermal stability with decomposition temperature being above 400°C. Some of them exhibited blue photoluminescence, in the range of 450-480 nm, making them promising candidates for future use as high performance materials in the construction of light emitting devices.     

Synthesis and evaluation of properties of novel poly(benzimidazole‐amide)s

Novel aromatic polyamides have been prepared by a combination of diacids containing preformed benzimidazole rings and aromatic diamines. By the phosphorylation method of polycondensation, polymers of high molecular weight (inherent viscosities between 0.81 and 2.13 dL/g) were obtained, which showed good solubility in polar aprotic solvents. The combination of aromatic amide linkages and benzimidazole rings along the polymer chain endowed the polymers with high thermal resistance and excellent mechanical properties. Glass transition temperatures fell in the range of 290–330 °C as measured by differential scanning calorimetry, and initial decomposition temperatures under nitrogen were over 480 °C as measured by thermogravimetric analysis. Some polymer films showed outstanding tensile strength (over 150 MPa) and moduli (up to 5 GPa). The presence of benzimidazole rings in the current polyamides greatly enhanced their hydrophilicity in comparison with classical wholly aromatic polyamides; thus, although aromatic polyamide films normally show water sorption values of only 4–8%, some of the current poly(benzimidazole amide)s show water sorption up to 19% in a 65% relative humidity atmosphere. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7566–7577, 2008     

New silicon-containing heterocyclic polyimides

New aromatic polyimides and polyamide-imides with phenylquinoxaline rings and dimethylsilane units have been synthesized by solution polycondensation reaction of aromatic diamines containing phenylquinoxaline units with bis(3,4-dicarboxyphenyl)-dimethylsilane dianhydride, or with a diacid chloride resulting from the reaction of this dianhydride with p-aminobenzoic acid. These polymers were easily soluble in organic solvents, such as N-methylpyrrolidinone and dimethylacetamide, and showed high thermal stability with decomposition temperature being above 440°C and glass transition temperature in the range of 245-285°C. Very thin coatings were deposited from polymer solutions onto silicon wafers and exhibited smooth, pinhole-free surface in atomic force microscopy investigations. Some of these polymers showed blue fluorescence in solution and films, with a maximum in the range of 415-425 nm.     

New methods of C-C and C-O bond formation in the synthesis of conjugated polymers

New synthetic developments towards polymers containing aromatic building blocks in the polymer backbone are described. The synthesis of polyphenylene-related systems with an improved solubility due to their alkyl substitution is discussed. Via bridging of the phenylene rings a twisting of the aromatic subunits is avoided and the conjugation improved. This concept is extended to ribbon-type polymers containing 6- or 6- and 5- membered rings. It is demonstrated that during a polycondensation process anthracene can be incorporated into various polymers via C-O bond formation as well as via C-C connection. Cycloaddition reactions are presented, allowing for modification and grafting of these polymers. Additionally, the use of anthracene derivatives as initiators in homo and block copolymerisation is shown.     

Polyphenylquinoxalines with high glass transition temperatures via highly fused aromatic tetraamines

A series of polyphenylquinoxalines has been synthesized by the reaction of p,p′-oxydibenzil with aromatic tetraamines containing varying numbers of fused rings. It was found that the glass transition temperatures of the resultant polymers increased as the the number of adjacent fused rings in the polymers was increased. This provided the basis for achieving glass transition temperatures for the polymers in excess of 400°C, substantially higher than the state-of-the art polyphenylquinoxalines. All of the polymers displayed both the good thermal stability and the solubility in m-cresol characteristic of the polyphenylquinoxaline family of polymers.     

COMPARED PROPERTIES OF FLUORINATED HETEROCYCLIC COPOLYIMIDES

Various new fluorinated heterocyclic copolyimides have been synthesized by a polycondensation reaction of a diacid chloride containing imide, hexafluoroisopropylidene and methylene groups with aromatic or heteroaromatic diamines containing preformed phenylquinoxaline or 1,3,4-oxadiazole rings. Other fluorinated heterocyclic copolyimides have been prepared by a polycondensation reaction of the same diacid chloride with aromatic dihydrazides, bis(o-hydroxy-amine)s or a bis(o-carboxy-amine), resulting in intermediate polyhydrazides, poly(o-hydroxy-amide)s or poly(o-carboxy-amide), respectively, which were futher cyclodehydrated to the corresponding polyoxadia zole-imide, polybenzoxazole-imide or polybenzoxazinone-imide structure. These polymers showed good solubility in polar amidic solvents, such as N-methylpyrrolidinone (NMP) and dimethylformamide (DMF), and even in less polar liquids, like tetrahydrofurane or pyridine, except for those compounds containing benzoxazole rings which were less soluble, only on heating in NMP or DMF. The weight average molecular weight measured for tetrahydrofurane-fully-soluble polymers are in the range of 12800–26700 and the polydispersity is in the range of 2–5. All these polymers exhibited good thermal stability, with decomposition temperature being above 350°C, although somewhat lower than that of related polymers prepared by using fully aromatic diacid chlorides instead of the present ones containing methylene units. The glass transition temperature is in the range of 200–300°C. The dielectric constant measured for polymer films is in the range of 3.3–3.7. Tensile strength is in the range of 35–70 MPa, elongation to break between 30–40% and tensile modulus in the range of 170–330 MPa. A study of the relation between conformational parameters and properties of some of these polymers has been carried out by using the Monte Carlo method with an allowance for hindered rotation, and the values were compared with the experimental data and discussed in relation with the rigidity of the chains. The present polymers are potential candidates for use as high performance materials.     

侧链对聚对苯撑乙炔溶解性和光谱性能的影响

利用钯催化反应合成了一类侧链含不同烷氧取代基(甲氧基，辛烷氧基，十二烷氧基)的聚时苯撑乙炔，讨论了侧链烷氧取代基对聚对苯撑乙炔的分子量和溶解性的影响，比较了聚合物的紫外吸收光谱和荧光光谱特征。     

Synthesis and characterization of soluble fluorine‐containing polyimides based on 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene

The synthesis and properties of a class of soluble fluorine‐containing aromatic polyimides are described. Substituents of trifluoromethyl groups on the aromatic rings of paralinked aromatic ether diamine conferred the polymer prepared thereof with enhanced solubility, low‐moisture absorption, and low dielectric constants. The polyimides also exhibited exceptional thermal stability, good mechanical properties, and excellent hygrothermal resistance. These outstanding combined features ensure the polymers are desirable candidate materials for advanced microelectronics applications. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2581–2590, 2001     

Low-temperature mechanical relaxations in polymers containing aromatic groups

Studies have been made of the secondary relaxation processes in the solid state of a number of polymers containing aromatic groups in the polymer chain. The polymers investigated include one, polystyrene, with the aromatic group in side-chain positions, and six high polymers in which phenylene rings lie in the main backbone chain. In polystyrene, wagging and torsional motions of the side chain phenyl rings give rise to a low-temperature δ-relaxation which is centered at 33°K (1.7 Hz) and which has an activation energy of about 2.3 kcal/mol. Most of the polymers with phenylene rings in the main chain exhibit a low-temperature relaxation in the temperature region from 100°–200°K. This relaxation process is centered at 159°K (0.54 Hz) in poly-p-xylylene, at 162°K (0.67 Hz) in polysulfone, and at 165°K (1.24 Hz) in poly(diancarbonate). In poly(2,6-dimethyl-p-phenylene oxide), two overlapping low-temperature relaxations are found, one in the range 125–140°K and the other near 277°K (ca. 1 Hz). The low-temperature secondary relaxation process in all of these polymers is believed to be associated with local reorientational motion of the phenylene, or substituted phenylene, rings or with combined motion of the phenylene rings and nearby chain units. For these low temperature relaxation processes, the activation energy is about 10 kcal/-mole. The temperature location of the relaxation appears to depend on the specific units to which the phenylene rings are attached and on steric and polar effects caused by substituents on the ring. In the poly-p-xylylenes the relaxation is shifted to much higher temperatures by a single Cl substitution on the ring but remains at essentially the same temperature position when dichlorosubstitution is made. The effects of water on the magnitude and temperature location of the observed low temperature relaxations, as well as the implications of the study for other polymers containing aromatic groups in their backbone chains, are discussed.     

Monolayers of methacrylic polymers containing aromatic groups

Monolayers of poly-methacrylates containing either aromatic or linear side groups were studied at the air-water interface. The aim of the work is to define the role of the aromatic group in determining the interfacial distribution and orientation of these polymers. Surface pressure measurements show that all the polymers give stable expanded monomolecular films between 288 K and 308 K temperature range.Surface potential and ellipsometric measurements show that both aromatic and aliphatic polymers are in an almost horizontal conformation at the liquid-air interface. From a comparison of the experimental isotherms with Huggins' theory, it was deduced that no preferential interactions exist between benzene rings in the film. In contrast, preferential attractive energies are observed for n-alkylmethacrylates.Further information on the state of the collapsed film was obtained from electron scanning micrographs.     

Aromatic polyimide-co-amides. I

A series of aromatic polyimide-co-amides of high thermal stability were synthesized. Low-temperature solution condensation involving aromatic diamines of varying basicity and bifunctional carboxylic acid chlorides containing performed imide rings was empolyed. This approach offers several advantages over the conventional polyamic acid route. The final polymers obtained are linear, soluble, and of high molecular weight. Solution of the final polymers are stable in contrast to polyamic acid solutions, which depolymerize hydrolytically due to the neighboring-group effect. Tough, flexible films were cast from solution and required no heat cure. The properties of one polymer made by the preformed ring approach were compared to its structurally related amide and imide homologs.     

Structure and substitution effects on the thermotropicity of some polyesters and model compounds

Abstract

The variations which occur in the thermal stability of the nematic mesophase as a function of the structure of the mesogenic moiety are considered here for the role played by three types of modifications. These are changes in the chemical nature of the mesogenic group, variation of the axial ratio of the rigid core and the presence of lateral substituents on the aromatic rings. Low molecular weight and polymeric liquid crystals of similar chemical nature have been investigated in order to see if parallel structure—property relationships exist between the two groups of compounds. In particular, starting from a mesogenic group built up of three aromatic rings connected by ester bonds, we have introduced the following modifications: (i) substitution of the central —COOC₆H₄OOC—with the—CH[dbnd]N—N[dbnd]CH— group; (ii) addition of two oxybenzoic end units to increase the length of the mesogenic moiety; (iii) introduction of two or more lateral methoxy substituents on the aromatic rings. The compounds were obtained by low temperature solution esterification between acyl chlorides and phenolic derivatives in the presence of a tertiary amine. Syntheses generally took place through the preliminary preparation of suitable intermediates. The thermal stability and the nature of the mesophases have been examined by different techniques. An interpretation of the results on the basis of the axial ratio and the strength of orientation dependent mutual attractions is attempted for model compounds. As far as polymers are concerned thermodynamic parameters follow the expected trend, if compared with those of low molecular weight analogues. Qualitatively models and polymers exhibit a similar dependence of mesophase stability on geometrical and electronic effects.     

Structure and substitution effects on the thermotropicity of some polyesters and model compounds

The variations which occur in the thermal stability of the nematic mesophase as a function of the structure of the mesogenic moiety are considered here for the role played by three types of modifications. These are changes in the chemical nature of the mesogenic group, variation of the axial ratio of the rigid core and the presence of lateral substituents on the aromatic rings. Low molecular weight and polymeric liquid crystals of similar chemical nature have been investigated in order to see if parallel structure—property relationships exist between the two groups of compounds. In particular, starting from a mesogenic group built up of three aromatic rings connected by ester bonds, we have introduced the following modifications: (i) substitution of the central —COOC₆H₄OOC—with the—CH=N—N=CH— group; (ii) addition of two oxybenzoic end units to increase the length of the mesogenic moiety; (iii) introduction of two or more lateral methoxy substituents on the aromatic rings. The compounds were obtained by low temperature solution esterification between acyl chlorides and phenolic derivatives in the presence of a tertiary amine. Syntheses generally took place through the preliminary preparation of suitable intermediates. The thermal stability and the nature of the mesophases have been examined by different techniques. An interpretation of the results on the basis of the axial ratio and the strength of orientation dependent mutual attractions is attempted for model compounds. As far as polymers are concerned thermodynamic parameters follow the expected trend, if compared with those of low molecular weight analogues. Qualitatively models and polymers exhibit a similar dependence of mesophase stability on geometrical and electronic effects.     

Synthesis and sulfonation of poly(arylene ether)s containing tetraphenyl methane moieties

Novel poly(arylene ether)s with sulfonic acid containing pendent groups were successfully synthesized by the nucleophilic displacement of aromatic dihalides with bisphenols in an aprotic solvent in the presence of excess potassium carbonate followed by sulfonation with chlorosulfonic acid. The sulfonation took place only at the controlled positions on the phenyl rings due to the novel bisphenol structures designed. The sulfonic acid group containing polymers were very soluble in common organic solvents, such as dimethyl sulfoxide, N,N′‐dimethylacetamide, and dimethylformamide, but swelled only slightly in water. These sulfonic acid group containing polymers were readily cast into tough and smooth films from organic solvents. The synthesized polymers had high glass‐transition temperatures of 171.0–240.7 °C and high molecular weights of 15,600–33,000 Da. These films could potentially be used as proton‐exchange membranes for fuel cells. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1779–1788, 2004     

Compared properties of related aromatic poly(1,3,4-oxadiazole-amide)s

Two series of aromatic poly(1,3,4-oxadiazole-amide)s have been synthesized by low-temperature solution polycondensation reaction of equimolar amounts of aromatic diamines containing preformed oxadiazole rings with diacid chlorides having silicon or hexafluoroisopropylidene groups. These polymers are soluble in polar aprotic solvents and show high thermal stability with decomposition temperature being above 400 °C and glass transition temperature in the range of 250-350 °C. The polyoxadiazole-amides have weight- and number-average molecular weights in the range of 207 000-330 000 and 77 000-131 000, respectively. Conformational parameters of these polymers were calculated by Monte Carlo method with allowance for hindered rotation and discussed in relation with thermal properties. Polymer solutions in NMP were processed into thin free-standing films that showed good mechanical properties with tensile strength in the range of 50-100 MPa, tensile modulus in the range of 2.25-3.56 GPa and elongation to break in the range of 1.65-8.58%.     

SYNTHESIS AND CHARACTERIZATION OF AROMATIC LIQUID CRYSTALLINE COPOLYESTERS WITH REGULAR SEQUENCE STRUCTURE

Several novel aromatic liquid crystalline copolyesters with regular sequence structure were prepared by melt Sehotten-Baumann polycondensation via complex monomer. Polarizing microscope with hot stage, thermal analysis and X-ray diffraction were used to investigate the structure and properties of the copolyesters. The effects of structural units, such as flexible spacer, noncolinear meta-linked phenylene unit, crankshaft unit, kink with flexible bridging unit and various substituted benzene rings on melting temperature of aromatic copolyesters were studied and discussed on the basis of crystalline structure of the polymers.     

Polythioamides aromatiques: Synthese et etude des comportements thermique et ensolution

Aromatic polythioamides are obtained by polycondensation of alkyl and/or carboxymethyl bis(dithioesters) with aromatic or aliphatic diamines in aqueous or organic solvents. We have identified the effect of aromatic rings on the behaviour of polymer in solution and thermal features on these condensation polymers. Their thermal stability is improved over that of aliphatic compounds, especially when the ring and the functional groups are conjugated.     

Molecular structure parameters in certain semiconducting polymers

The condensation polymers formed by condensing aromatic hydrocarbons or their derivatives with aromatic acids are quite conductive. The room temperature resistivities of 42 polymers studied here range from 10² to 10¹² ohm-cm. It is found that the resistivities are inversely related to the number of fused rings in the hydrocarbon portion of the monomer for either the homopolymers or copolymers. The resistivities are strongly dependent, inversely, upon the acid strength of the acid monomer reactants. For all the polymers studied, the conductivity σ depended upon the pressure P as ln(σ/σ₀) = (b^*/k)P^1/2 where b^* is seen to be an inverse function of the number of fused rings in the monomer in accord with theory. The resistivity ρ varied with absolute temperature T, as ln ρ ∞ (1/T) for all polymers. Thermoelectric powers were determined, and the various relationships established among energy interval, resistivity at “infinite temperature,” carrier concentrations and mobility ratios, number of fused rings, and pressure coefficients are discussed. The polymers are p-type. Doping by Be⁺⁺ or Cu⁺⁺ has a small effect, increasing the conductivity slightly. Electron spin concentrations and carrier concentrations are directly related among the polymers, being found nearly equal for the most conductive but differing by up to nine orders of magnitude in the least conductive polymers.