Polycarbonates and polyesters containing oxadiazole rings

Two new bisphenols containing an oxadiazole ring, 2,5-bis(p-hydroxyphenyl)-1,3,4-oxadiazole and 2,5-bis(m-hydroxyphenyl)-1,3,4-oxadiazole, were synthesized starting from p- and m-hydroxybenzoic acid and hydrazine. Polycarbonates having an inherent viscosity up to 0.5 were obtained by transesterification of the bisphenols with diphenyl carbonate. Similarly, aromatic polyesters were prepared from the corresponding diphenyl esters. These polycarbonates and polyesters were insoluble in all organic solvents, and indicated a high degree of crystallinity. The melting point of all the polymers containing oxadiazole rings were much higher than that of the polymers derived from bisphenol A.     

Aliphatic polyamides containing tricyclic fused rings

A series of polyamides containing thianthrene, phenoxathiin, and dibenzo-p-dioxin units were synthesized from the corresponding tricyclic fused ring diamines and aliphatic diacid chlorides by solution polycondensation at low temperature. These polyamides showed improved thermal stability, while maintaining the good solubility of aliphatic polyamides. The thermal stability of the series of polyamides increased in the order of the thianthrene containing polymers < phenoxathiin containing polymers < dibenzo-p-dioxin containing polymers. Glass transition temperatures of these polymers were estimated by thermomechanical analysis as well as by temperature-resistivity curves. Polyamides derived from 2,8-oriented tricyclic diamines showed somewhat lower glass transition temperatures than those from 2,7-oriented diamines.     

Synthesis and properties of new semifluoroalkylene-containing aromatic-aliphatic polyamides derived from aromatic diamines and semifluoroaliphatic dicarboxylic acids

New semifluoroalkylene-containing aromatic-aliphatic polyamides having number-average molecular weights of 30 000–119 000 were prepared by the direct polycondensation of various aromatic diamines with octafluorodecanedioic and dodecafluorododecanedioic acids in NMP using the triphenyl phosphite-pyridine system as a condensing agent. All the fluorine-containing polyamides are highly soluble in a variety of organic solvents including NMP and DMAc, compared with the fluorine-free counterpart polymers. Most of the polyamides are crystalline and have melting temperatures of 195–272°C, which are lower than those of the corresponding fluorine-free polymers. These fluorine-bearing polyamides have glass transition temperatures of 134–178°C, and begin to lose weight at about 320–340°C in nitrogen. The contact angles of film surfaces of the fluorine-containing polyamides to water are in the range of 77–103°, which are higher than those of the fluorine-free polyamides.     

Synthesis and properties of polyamides derived from anhydro- and dianhydroalditols

The three isomeric 1,4:3,6-dianhydroalditols with D -gluco- ( 2 ), D -manno- ( 11 ) and L -ido ( 17 ) configuration and both 1,4-anhydroalditols with threo ( 22 ) and erythro ( 27 ) configuration were efficiently transformed into the corresponding diamino derivatives. Interfacial polycondensation of these chiral heterocyclic diamines with purchasable aromatic and aliphatic carboxylic acid chlorides gave polyamides 35 and 36a–f, 37, 38 and 39a–d . The polymers were characterized using IR and ¹H/¹³C NMR spectroscopy. Number-average molecular weights were obtained from gel-permeation chromatography to be M?_n ≈ 5000–25000 corresponding to a number-average degree of polymerization up to P?_n ≈ 100. Inherent viscosities were measured, and differential scanning calorimetry gave information on the thermal properties of the polymers.     

Synthesis and properties of aromatic polyamides derived from 2,7-bis(4-aminophenoxy)napthalene and aromatic dicarboxylic acids

2,7-Bis(4-aminophenoxy)naphthalene, a new polymer-forming diamine, was synthesized in two steps by the preparation of 2,7-bis(4-nitrophenoxy)naphthalene from 2,7-dihydroxynaphthalene and p-chloronitrobenzene and subsequent reduction with a 10% Pd-C catalys and hydrazine hydrate. Aromatic polyamides and copolyamides having an inherent viscosity in the range of 0,76–1,16 dL/g were prepared by the direct polycondensation of the diamine with various aromatic dicarboxylic acids or with mixed dicarboxylic acids in 1-methyl-2-pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Most of the polymers were soluble in aprotic solvents such as NMP and N,N-dimethylacetamide (DMAc), and afforded transparent, flexible and tough films upon casting from DMAc solutions. Glass transition temperatures of the polymers were in the range of 246–327°C, and 10% weight loss temperatures were above 501°C in nitrogen and 476°C in air, respectively.     

Syntheses of polyamides containing theophylline and thymine

2-(1,3-Dimethyl-2,6-dioxo-2,6-dihydropurin-7-yl)methylsuccinic acid ( 2a ) and 2-(5-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)methylsuccinic acid ( 2b ) were synthesized via the addition reaction of theophylline and thymine, respectively, to dimethyl methylenesuccinate, followed by hydrolysis of the resulting ester. The dicarboxylic acid derivatives 2a and 2b were further converted to their di-p-nitrophenyl esters 3a and 3b , which were allowed to polycondense with diamines such as 1,6-diaminohexane, 1,2-diaminoethane, 3-aminomethylbenzylamine, and piperazine in solutions. The resulting polyamides are white powders with molecular weights in the range of about 2000–6000. The DP of the polyamides varies with the kind of diamines and solvent used. All polyamides are soluble in DMSO and formic acid, the polyamides deriving from esters 3a and 3b and 1,2-diaminoethane and piperazine are also soluble in water.     

Syntheses of polyamides containing uracil and adenine

2-(2,4-Dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)methylsuccinic acid ( 2a ) and 2-(6-aminopurin-9-yl)methylsuccinic acid ( 2b ) were synthesized through the addition reaction of uracil and adenine, respectively, to dimethyl methylenesuccinate, followed by hydrolysis of the resulting dimethyl esters. Dicarboxylic acid 2a was further converted to the corresponding di-p-nitrophenyl ester 3a and dicarboxylic acid 2b was converted to the di(cyanomethyl) ester 3b . The active esters 3a and 3b were polycondensed with diamines such as 1,2-diaminoethane, 1,6-diaminohexane, 4-aminomethylbenzylamine, and piperazine in solution, giving polyamides containing uracil and adenine as the side group. The polyamides were found to have molecular weights in the range of about 1000–5000. The polyamides derived from 1,2-diaminoethane and piperazine were soluble in water.     

Synthesis of polyamides containing cytosine and hypoxanthine

The di(cyanomethyl) methylsuccinate derivative of cytosine and di(p-nitrophenyl) methyl-succinate derivative of hypoxanthine were prepared and polycondensed with a variety of diamines to provide powdery polyamides with molecular weights in the range of 1000–3100. The polyamides are soluble in DMSO and formic acid, but insoluble in ordinary organic solvents.     

New polymer syntheses, 65. New terephthalic acids with aromatic substituents and thermotropic polyesters derived from them

New terephthalic acids with aromatic substituents were prepared in two different ways. A first attempt was made by nucleophilic substitution of dimethyl nitroterephthalate with phenoxide ions. The formation of phenyl methyl ethers is a significant side reaction in this procedure. The second method consists in the arylation of dimethyl 2-(4′-hydroxyphenylthio) terephthalate with activated fluoroaromatics. Insufficient electrophilicity of the fluoro compound is here the limiting factor. Thermotropic polyesters were prepared from 4,4′-biphenyldiol and various arylthioterephthalic acids. It was found that increasing length of the aromatic side chain improve both solubility and meltability. All polyesters form a nematic phase above their melting point (T_m).     

Preparation of polyamides containing α-diketone moieties and their transformation into 1,2,4-triazine rings with amidrazones

Polyamides 3–5 containing 1,2,4-triazine rings in the main chain were prepared by condensation of amidrazones 2 with polyamides 1 containing α-diketone moieties, with conversions between 10 and 87%. The thermal stabilities and the solubilities of the resulting polymers 3–5 were enhanced by the introduction of the 1,2,4-triazine rings in the main chain.     

Asymmetrically substituted liquid-crystalline phthalocyanines and side-chain polymers derived from them

Asymmetrically substituted, liquid-crystalline phthalocyanines were synthesized. They contain one methoxy, six dodecyloxy and one acryloyloxy- or methacryloyloxydodecyloxy groups. The latter functions were polymerized under free radical conditions to give polymers with molecular weights between 9000 and 47000. The aggregation behaviour of the phthalocyanines in the polymer side chains was studied in solution by absorption and fluorescence spectroscopy. An enhanced intramolecular interaction between the phthalocyanines was observed. In the solid state this interaction is reflected in the spontaneous formation of a columnar structure. The polymers, however, do not display liquid-crystalline behaviour. Temperature-dependent luminescence measurements (at 4,2 – 300 K) were performed and the results are explained by the presence of an efficient energy migration process through the stacked phthalocyanine units.     

Biodegradable polymers derived from amino acids

This report describes general methods for the synthesis of biodegradable poly(amide anhydrides) and poly(amide esters) based on naturally occurring amino acids. The polymers were synthesized from dicarboxylic acids prepared by amidation of the amino group of an amino acid with a cyclic anhydride, or by amide coupling of two amino acids with a diacid chloride. This approach was demonstrated by the synthesis of polymers based on alanine and proline. Homo- and copolyanhydrides with sebacic acid of β-alanyl succinamide, and N,N'-bis(β-alanine)-1,3-benzene dicarboxamide, were synthesized by melt or solution polymerization. The copolymers prepared in solution had molecular weights up to 4500, while the copolymers prepared by melt condensation had higher molecular weights of about 30 000. Polymers were also prepared directly from the reaction of an amino acid and a diacid chloride. These polymers were soluble in dichloromethane and had molecular weights in the range 800–4800. A polyester of -prolyl succinamide was prepared by melt condensation of the methyl ester derivative of the diacid and propylene glycol with acid catalysis. The polymer was transparent and pliable, and had a weight average molecular weight of 33 000. The poly(amide anhydrides) based on alanine and sebacic acid display a nearly linear degradation pattern with complete degradation in vitro after 5–10 d (phosphate buffer, pH 7.4 at 37°C).     

Preparation of polyamides having 1,2,4-triazine rings in the main chain

Polyamides having 1,2,4-triazine rings in the main chain ( 6 and 7 ) were prepared from 3-substituted 4,4′-(1,2,4-triazine-5,6-diyl)dibenzoic acids ( 5 ) and aromatic diamines. The thermal stability and the solubility of polyamides 6 and 7 were compared with those of structurally identical polyamides (polymers 3 and 4 ) obtained by polymer homologous reaction of polyamides having α-diketone moieties with amidrazones. The effects of introduction of 1,2,4-triazine-5,6-diyl unit in the main chain on the thermal stability and solubility of the polymers are discussed.     

Preparation and properties of polyamides containing dibenzothiphenediyl and 5,5-dioxodibenzothiophenediyl units

Several new polyamides ( 3a–d , 6a–d , 7a and 7b ) containing dibenzothiophenediyl units were prepared by low temperature solution polycondensation of dibenzothiophenediamines ( 1a, b ) with aromatic diacyl dichlorides ( 2a, b ) or of aromatic diamines ( 5a, b ) with dibenzothiophenediacyl dichlorides ( 4a, b ). Some of the polymers were soluble in polar amide solvents or DMSO. All the polymers possess inherent viscosities in the range of 0,6 to 1 dl/g. Thermal stability and crystallinity were determined. The resulting polyamides were found to be much more stable than the corresponding polymers having open-chain linkages.     

Synthesis and characterization of some novel polyamides containing diacetylene side groups

A series of novel polyamides containing diacetylene groups as side chains were prepared by Cadiot-Chodkiewcz-coupling of polymer precursors bearing 2-propynyloxy side groups with 4-bromo-3-butyn-1-ol. The conversion of the acetylenic groups was in the range of 87.5–96.5% depending on the chemical structure of the polymer backbone. The polymers are highly amorphous and undergo random cross-linking on heating. Thermally treated polymer films show third-order nonlinear optical susceptibility χ(3) of the order of 10⁻¹⁰ esu (= 10⁻¹⁸m⁵/V²).     

Pasty injectable biodegradable polymers derived from natural acids

Pasty biodegradable polymers that can be mixed with drugs at room temperature and injected to tissue as neat composition are advantageous as they allow simple preparation and delivery of drugs, particularly for heat sensitive drugs. A series of biodegradable pasty poly (ester-anhydride)s were prepared from alkanedicarboxylic acids and ricinoleic acid and its oligomers by transesterification-repolymerization method. The polymers were characterized by common spectroscopic, chromatography, and thermal methods. Polymers containing 70% ricinoleic acid and 30% linear dicarboxylic acids with 4-10 methylene groups were synthesized. The melting point of these poly (ester-anhydride)s increased as the number of methylenes in the alkanedicarboxylic acid increased. Use of short oligomers of ricinoleic acid instead of ricinoleic acid itself increased the melting point and decreased the softness of the resulting polymers. The polymers released model drugs for a few weeks while being degraded to their fatty acid counterparts. Copolymerization of alkanedicarboxylic acids with ricinoleic acid resulted in pasty biodegradable polymers useful as injectable carriers for drugs.     

Synthesis of polyamides containing 4,4′-azodibenzamido units

Four coloured polyamides containing azo-p-phenylene units were synthesised from 4,4′-azodibenzoic acid and four aromatic diamines employing both interfacial and solution polymerization procedures. The polymers were characterized by their UV and IR spectra, by inherent viscosity measurements and by solubility data. The stability in conc. sulfuric acid and the thermal behaviour are discussed.     

Synthesis of polyamides from esteramide-diamines

Diamines containing ester and amide linkages were obtained by the addition reaction of p-aminobenzoic acid with arylenebis(2-oxazolines) in N,N-dimethylformamide. These diamines were subjected to polycondensation with various diacid dichlorides to obtain polyamides containing regular ester and amide sequences in the polymer chain.