Synthesis,optical absorption and fluorescence of new poly(p-phenylene)-related polymers

The synthesis and properties of soluble, conjugated polymers consisting of oligo(p-phenylene) sequences linked by ethylene, vinylene, or ethylene, units are reported. Benzene-, stilbene-, diphenylacetylene- and 1,2-diphenylethane derivatives serve as monomers and are connected by the Suzuki-coupling method. A wide range of poly-(p-phenylene)-related polymers are available by the combination of different AA/BB-type monomers in various concentrations. The optical properties of the resulting polymers can therefore be tailored. Number-average degrees of polymerization of up to X̄_n = 137 were reached under optimized conditions. Photoluminescence quantum yields of these materials in solution are nearly one.     

New synthesis of polyaromatics through oxidative polymerization by using metal complexes with air

The oxidative polymerization provides a new synthetic route to polyaromatics. Poly(p-phenylene sulfide) (PPS) is produced by oxidative polymerization of thiophenol with a vanadyl complex catalyst. The metal complexes act as an efficient catalyst of oxygen oxidative polymerization. The polymerization to yield PPS is discussed especially focusing on the catalytic mechanism of the complexes.     

Synthesis of poly(tert-butoxycarbonyl-p-phenylene): precursor to poly(p-phenylene)

Poly[2-(tert-butoxycarbonyl)-1,4-phenylene] ( 2 ) was prepared by the Ni-catalyzed polymerization of tert-butyl 2,5-dichlorobenzoate ( 1 ). The microstructure of polymer 2 was probably alternating head-to-head and tail-to-tail. This polymer was soluble in dipolar aprotic solvents, chloroform, tetrahydrofuran, and dichloromethane. Polymer 2 was saponified easily by thermal or acid treatment to yield poly[2-carboxy-1,4-phenylene] ( 3 ). Decarboxylation of polymer 3 in quinoline in the presence of copper(II) oxide produced poly(p-phenylene) (PPP) ( 4 ).     

Synthesis and polymerization of novel formamidinium salts: A new pathway to polyamides derived from aromatic diamines

A new polycondensation pathway has been developed for the preparation of polyamides at high temperatures. p-Phenylenediamine was converted to N,N-p-phenylene bis(N′,N′-dimethylformamidine) (I), which formed 1–1 and 2–1 salts with terephthalic and adipic acids, respectively: Dicarboxylate salts were polymerizable by heating in bulk or suspension. Low-molecular-weight poly(p-phenyleneterephthalamide) was obtained from N,N-p-phenylene bis(N',N'-dimethylformamidinium) terephthalate above 225°C. The low degree of polymerization was due to terephthalic acid sublimation as well as to the well-known intractability of poly(p-phenyleneterephthalamide). High-viscosity poly(p-phenyleneadipamide) was obtained from N,N-p-phenylene bis(N′,N′-dimethylformamidinum hydrogen adipate) above 200°C. Both salts liberated dimethylformamide (DMF) during polymerization. The adipate salt also released 1 mole of adipic acid during the high-temperature vacuum stage of polymerization. A polycondensation mechanism was proposed for each salt, based on thermal gravimetric analysis (TGA-MS) and infrared (IR) analyses. The hydrolysis of N,N-p-phenylene bis(N',N'-dimethylformamidine), N,N-p-phenylene bis(N',N'-dimethylformamidinium chloride), and the two dicarboxylate salts of (I) was monitored by nuclear magnetic resonance (NMR) at room temperature. The dihydrochloride salt was most resistant to hydrolysis (k_H 6.9 × 10^?9 sec^?1; relative rate 1.0) followed by (I) 7.1, terephthalate salt, 14.9, and adipate salt, 27.2. Both dicarboxylate salts possessed sufficient hydrolytic stability for use as polycondensation monomers     

The synthesis and solution properties of some rigid-chain,water-soluble polymers: Poly[N,N′-(sulfo-phenylene)phthalamide]s and poly[N,N′-(sulfo-p-phenylene)pyromellitimide]

Poly[N,N′-(sulfo-phenylene)phthalamid]es and poly[N,N′-(sulfo-p-phenylene)pyromellitimide] were prepared in water-soluble form and were found to have unique solution properties, similar in some respects to xanthan. The polymer most investigated, poly[N,N′-(sulfo-p-phenylene)terephthalamide] (PPT-S), is produced as the dimethylacetamide (DMAC) salt by the solution polymerization of 2,5-diaminobenzenesulfonic acid with terephthaloyl chloride in DMAC containing LiCl. The isolated polymer requires heating in water to dissolve; the resulting cooled solutions are viscous or gels at concentrations as low as 0.4%. They are highly birefringent, exhibit circular dichroism properties, and are viscosity-sensitive to salt. Solutions of this polymer mixed with those of guar or hydroxyethyl cellulose give significantly enhanced viscosity. The polymer is relatively low molecular weight, ca. 5000 estimated from viscosity data. Some meta and para isomeric analogs of PPT-S were prepared; these polymers have similar properties except they are more soluble in water, and higher concentrations are required to obtain significant viscosity. Poly[N,N′-(sulfo-p-phenylene) pyromellitimide] (PIM-S) was prepared similarly from 2,5-diaminobenzenesulfonic acid and pyromellitic dianhydride. Its aqueous solution properties are similar to those of PPT-S. It appears that these relatively low-molecular-weight rigid-chain polymers associate in water to form a network that results in viscous solutions at low concentrations.     

Syntheses and properties of polymers from perchloro-p-xylene,perclorobi-p-tolyl,and perchloro-m-xylene with Fe(CO)5 as dechlorinating agent

We describe a new method for the polymerization of perchloroaromatic compounds using Fe(CO)₅ as a dechlorinating agent which allows the syntheses of perchloropoly-1,4-phenylene vinylene ( 8 ), perchloropoly-4,4'-biphenylene vinylene ( 9 ), and perchloropoly-1,3-phenylene vinylene ( 10 ) from perchloro-p-xylene ( 5 ), perchlorobi-p-tolyl ( 6 ), and perchloro-m-xylene ( 7 ), respectively. Polymer 10 , a new macromolecular chlorocarbon, was characterized by elemental analysis and infrared and ultraviolet spectra. The molecular weights (MW's) of the polymers were estimated by osmometry. The XPS spectra of these polymers are discussed. Their thermal properties were studied by thermogravimetry. Electron spin resonance (ESR) studies and some preliminary conductivity measurements, made after doping the polymers with SbF₅, are reported. © 1992 John Wiley & Sons, Inc.     

Polymidines. V. Poly[(3,3-diphenyl-2,6-phthalimidinediyl)-carbonyl(3,3-diphenyl-6,2-phthalimidine)]s

A new diphthalide monomer, bis(3,3-diphenyl-6-phthalidyl) ketone, was polymerized with six diamines: 1,6-diaminohexane, benzidine, p-phenylene diamine, p,p′-diaminodiphenyl ether, p,p′-diaminodiphenylmethane, and 4,4′-diaminodiphenylsulfone. Solution polymerization in benzhydrol, biphenyl, or p-phenylphenol solvents gave low-molecular-weight polymers (inherent viscosity 0.13 dl/g or less) which were soluble in chloroform and dimethylformamide. TGA data showed 10% weight losses at 445–525°C in air and 475–540°C in nitrogen for the aromatic backbones. Yields ranged from 47 to 78%. The application of continuous vacuum to the polymerization allowed the removal of water by-product and resulted in a light-colored polymer.     

Synthesis of rod-coil block copolymers via end-functionalized poly(p-phenylene)s

This paper describes a new way to synthesize rod-coil block copolymers consisting of poly(p-phenylene) (PPP) as rigid rod and either polystyrene (PS) or poly(ethylene oxide) (PEO) as flexible coil. The Suzuki-coupling of the AB-type monomer 4-bromo-2,5-diheptylbenzeneboronic acid (1) under strictly proton-free conditions leads to the control of PPP endgroups and hence allows the synthesis of a variety of differently end-functionalized poly(p-phenylene)s. The poly(2,5-diheptyl-p-phenylene)-block-polystyrene (7) is then prepared via condensation via condensation of anionically polymerized living polystyrene ( 6 ) with α-(4-formylphenyl)-ω-phenyl-poly(2,5diheptyl-p-phenylene) ( 4 ). Toluenesulfonic acid catalyzed condensation of α-methyl-ω-amino-poly(oxyethylene) ( 8 ) with PPP 4 yields poly(2,5-diheptyl-p-phenylene)-block-poly(ethylene oxide) ( 9 ).     

Effect of structure on the thermal stability of polyimides

Polyimides with different proportions of m-phenylene and p-phenylene (or p,p′-biphenylene) were prepared by polymerizing different molar ratios of m-phenylene diamine and p-phenylene diamine (or p,p′-diaminobiphenyl) with pyromellitic dianhydride in dimethylformamide at 0°C. Chemical cyclodehydration of polyamic acids resulted in the corresponding polyimides. Polymers were characterized by infrared (IR), viscosity, and density measurements. Viscosity and density of polymers decreased with an increase on m-phenylene groups in the backbone. The thermal and thermooxidative stabilities were investigated by dynamic thermogravimetry. Stability decreased when m-phenylene groups were introduced in the backbone.     

Preparation of poly(phenylene vinylene) from cycloalkylene sulfonium salt monomers and polymers

Two new types of p-xylene bis-sulfonium chloride monomers were prepared from cycloalkylene sulfides. The polymerization characteristics of these monomers to form poly(p-xylene sulfonium chlorides), and the thermal elimination reactions of their polymers to poly(p-phenylene vinylene), were compared with those of two monomers prepared from dialkyl sulfides. The cycloalkylene sulfonium chloride monomer polymerized to higher yields and to higher molecular weight polymers, which showed more efficient elimination reactions.     

Preparation and thermal behavior of poly-p-phenylene diacrylic acid dimethyl ester

The photopolymerization behavior of p-phenylene diacrylic acid dimethyl ester (p-PDA Me) crystal and the thermal behavior of the resultant poly-p-PDA Me were investigated. From the kinetic study of polymerization at various temperatures a topochemical process via a stepwise mechanism was observed. Continuous change from monomer to polymer crystals was demonstrated by x-ray diffraction pattern and DSC analysis. Crystallinity of the reacting phase was maintained at an extremely high degree during the polymerization process in support of monomer crystal lattice control. Thermal study on as-polymerized poly-p-PDA Me crystal confirmed that the thermal reaction was a polymer crystal lattice-controlled depolymerization, which was followed by miscellaneous processes that involved vaporization, sublimation, and deterioration of the oligomeric or monomeric units of p-PDA Me. Thermal stability was dependent on the molecular weight. All the results are compared with those of four-center-type photopolymerization in the crystalline state.     

Preparation of soluble and fusible poly(2,5-dimethoxy-1,4-phenylene)

Poly(2,5-dimethoxy-1,4-phenylene) was prepared by oxidative polymerization of p-dimethoxybenzene with aluminum chloride and copper(II) chloride in nitrobenzene under reduced pressure. The polymers obtained were soluble in sulfuric acid and fusible at 320°C. The intrinsic viscosity of the polymer was ca. 0.07 in sulfuric acid. Demethylation of methoxy groups did not occur during the polymerization.     

Synthesis and solution properties of rodlike polyelectrolytes

The synthesis and the solution behavior of rigid, rodlike cationic polyelectrolytes having (i) poly(p-phenylene) backbones and (ii) main chains composed of 4,4“-bis(2,2′:6′,2”-terpyridine)2′,5′-dihexyl-p-terphenyl moieties and ruthenium(II) centers are presented. All these polymers are shown to have a homogeneous constitution and degrees of polymerization of up to P_n ≈ 70. Their solution properties were analyzed using viscosimetry, small-angle X-ray scattering (SAXS) and osmometry. Pronounced polyelectrolyte effects were found in salt-free solutions using viscosimetry. Small-angle X-ray scattering demonstrated directly the strong correlation of the counterions and the macroions. The osmotic coefficients measured in salt-free solution as function of polyelectrolyte concentration were found to be lower than predicted by the cell model.     

Studies on the thermotropic liquid-crystalline polymer. VIII. Synthesis and properties of fully aromatic poly(ester)s and poly(amide-ester)s containing p-phenylene diacrylic group

Three series of polymers containing p-phenylene diacrylic group were prepared by direct polycondensation in the presence of diphenylchlorophosphate and pyridine. Series I was prepared from p-phenylene bis(acrylic acid) with various hydroquinones. Series II was prepared from p-phenylene bis (β-cyano acrylic acid) with methylhydroquinone. Series III was prepared from 3-methyl-4-aminophenol with p-phenylene bis(acrylic acid) or p-phenylene bis(β-cyano acrylic acid), respectively. The phase behavior of these polymers was studied by differential scanning calorimetry (DSC), optical polarizing microscopy equipped with a heating stage, and wide-angle x-ray diffraction (WAXD). It was found that these polymers, except IIIb , exhibit thermotropic liquid-crystalline properties and show threaded or Schlieren texture under the optical polarizing microscopic observation. Furthermore, the melting temperatures of these polymers were decreased in the range of 254–354°C by incorporating with p-phenylene diacrylic group into the main chain. © 1993 John Wiley & Sons, Inc.     

Oxidative polymerization of p-phenylenediamine

Oxidative polymerization of p-phenylenediamine in a hydrochloric acid solution yields not a polyquinoxaline polymer as described in the literature but a modified poly(1,4-benzoquinonediimine-N,N′-diyl-1,4-phenylene) analogous to polyaniline known as pernigraniline. A new scheme of oxidative polymerization of p-phenylenediamine was suggested.     

Electrochemical preparation of poly(<Emphasis Type="Italic">p</Emphasis>-phenylene) thin films

We report the electrochemical preparation of poly(p-phenylene) (PPP) thin films with a polymerization degree of approximately 20 using biphenyl as starting material. The PPP films are prepared directly on a tin oxide electrode, presenting a positive charge carrier mobility of 5×10⁻⁷ cm² V⁻¹ s⁻¹.     

Structural studies of poly(paraphenylene), poly(2,5-thienylene) and their derivatives by solid-state NMR of 1H and 13C

Transient techniques in NMR of ¹H and ¹³C were used to study the chemical and physical structures of solid poly(p-phenylene) (PPP), poly(2,6-dimethyl-p-phenylene oxide) (PDMPO), poly(p-phenylene sulfide) (PPS), poly(p-biphenylene sulfide) (PPBS), poly(p-phenylene selenide) (PPSe), poly(p-biphenylene selenide) (PPBSe), poly(2,5-thienylene) (PT), poly(3-methyl-2,5-thienylene) (PMT), and poly(p-phenylene-co-2,5-thienlyene) (PPPT) of different monomer ratios. ¹³C NMR confirmed the expected chemical structure for homopolymers, and indicated a random distribution of monomer units in PPPT. Relative fractions of crystalline and interfacial regions were determined by measurements of ¹H magnetic relaxation, ¹³C CP/MAS NMR, and XRD. © 1994 John Wiley & Sons, Inc.     

Soluble substituted poly-p-phenylenes—A new material for application in light-emitting diodes

Poly-p-phenylenes have attracted a great deal of attention with respect to their applications in displays, light-emitting devices, and batteries. However, the polymer poly-p-phenylene obtained by the Kovacic method is insoluble and intractable. The present study reports the preparation of soluble poly(p-phenylenes) by polymerization of derivatives of benzene in the presence of a specific aromatic nuclei. The resultant copolymer so obtained is soluble in common organic solvents such as chloroform and toluene. Preliminary studies have indicated that the polymer shows orange photoluminescence and electroluminescence when a potential of 7–10 V is applied to the device.     

A novel scalable synthesis process of PPTA by coupling n-pentane evaporation for polymerization heat removal

In this study,we compared the effect of n-pentane and ice-water bath on removing the thermal effect in the poly（p-phenylene terephthalamide）（PPTA） polymerization process.The results indicate that the n-pentane can help to transfer the reaction heat faster and better.Adding suitable amount of n-pentanes into the PPTA preparation process not only improve the heat transfer,but also reduce the motor power in the polymerization process.Moreover,the introduction of n-pentane properly does not result in decrease of the inherent viscosity(η_inh) of polymer.Instead,it leads to increased viscosity of polymer during the PPTA preparation process.The results indicate that n-pentane can effectively transfer the reaction heat and avoid overheating during the polymerization of PPTA.