N-Alkyl-substituted polyamides and copolyamides having long methylene chain units

N-Alkyl-substituted polyamides and copolyamides have been prepared from N,N′-dialkyl p-xylenediamine and N,N′-dialkyl hexamethylenediamine with long-chain aliphatic dicarboxylic acids. Crystalline N-alkyl polyamides were obtained by the use of dicarboxylic acids higher than C₁₆. The melting point versus composition curves for the crystalline N-alkyl copolyamides which were prepared from a mixture of diamine and the corresponding N-alkyl diamine with α,ω-octadecanedioic acid showed convex type plots. X-ray examination of N-alkyl copolyamides revealed that all the systems behaved in the same basic manner, the second component was always present without dissolving in the lattice of the first. Dilatometric curves showed two inflection points, corresponding to the melting points of the N-alkyl and unsubstituted polyamides respectively. From these results, a block copolymer structure was suggested for the N-alkyl copolyamides. The mechanisms for the formation of the block structure were also discussed.     

Thermal properties of PA 6 and PA 6 modified with copolyamides and layered silicates

This article focuses on the thermal properties of PA 6 and additives, i.e. ternary copolyamides, concentrates consisting of binary or ternary copolyamides + nanoadditive montmorillonite Bentonite 11958 or Cloisite 15A and PA 6 fibres modified with Bentonite, copolyamide and concentrate. The copolyamides are prepared from ε-caprolactam as a major comonomer and nylon salts AN2 from adipic acid + 1-(2-aminoethyl)piperazine and ADETA from adipic acid + diethylenetriamine. All copolyamides and concentrates exhibit lower melting temperatures T _m and lower melting enthalpies ΔH _m compared to neat PA 6. PA 6 fibres modified with 0.25–2.5 wt% MMT exhibit higher melting enthalpies in comparison with unmodified PA 6 fibres. PA 6 fibres modified with 10 wt% of ternary copolyamide containing 21.4 wt% of comonomers AN2 and ADETA have higher melting enthalpy as well. PA 6 fibres modified with 10 and 20 wt% of concentrate containing the same ternary copolyamide + 5 wt% of MMT have higher melting enthalpies and higher tensile strength in comparison with these characteristics of unmodified PA 6 fibres.     

Polyamides having long methylene chain units

Three series of polyamides having long methylene chain units have been prepared from p-xylylenebisethylamine and 2,2′-pphenylenebisethylamine with aliphatic dicarboxylic acids of long methylene chain units; aliphatic diamines of long methylene chain units with terephthalic, p-benzenediacetic, and p-benzenedipropionic acids; and aliphatic diamines with aliphatic dicarboxylic acids, both having long methylene chain units. The effects of the length of the methylene chain units on the melting point, the glass transition temperatures and the densities of these polyamides were investigated. The aromatic polyamides, in which even methylene chains are joined between a phenylene and an amide group generally have higher melting points than the corresponding ones with odd methylene chains. On the plots of the melting points and the densities of the aliphatic series against the amide concentrations, both the melting point and the density extrapolated to the zero amide concentration are found below the values for polymethylene.     

Preparation and properties of aromatic–aliphatic copolyamides from aromatic diisocyanates and dicarboxylic acids

Aromatic–aliphatic random copolyamides of high molecular weights were prepared by the high-temperature solution polycondensation from a combination of aromatic diisocyanates, 4,4′-methylenedi(phenyl isocyanate), and 2,4-tolylene diisocyanate, and a mixture of isophthalic acid and aliphatic dicarboxylic acids with 4–10 methylene groups. Reaction conditions, such as solvent, temperature, time, and catalyst were studied to determine the optimum conditions for the preparation of high molecular weight polymers. Glass transition temperatures of the copolyamides were in the range of 131–244°C and varied with combination and composition of the diisocyanates and dicarboxylic acids used. The copolyamides prepared from 2,4-tolylene diisocyanate had greater solubility and higher glass transition temperatures than those obtained from 4,4′-methylenedi(phenyl isocyanate).     

Synthesis of fluorine-containing graft copolyamides by using condensation-type macromonomers

Fluorine-containing graft copolyamides were prepared from condensation-type macromonomers. Dicarboxyl-terminated poly(perfluoroalkylethyl acrylate) was prepared by radical chain transfer polymerization and copolycondensed with diamines and dicarboxylic acids in the presence of triphenylphosphine and pyridine. Nylon-6 films containing various amounts of the resulting graft copolyamides were obtained by heat pressing. Only 5 wt % of graft copolymers were sufficient to make nylon-6 surfaces water repellent.     

Thermal properties of poly-ε-caprolactam and copolyamides based on ε-caprolactam

The copolyamides consisting of ε-caprolactam and 6.1–24.5 wt.% of nylon salt prepared from adipic acid and 1-(2-aminoethyl) piperazine were synthesized. Physical and thermal characteristics of polyamide 6 and the copolyamides were compared. Nylon salt does not influence the polyreaction equilibrium so it is possible to prepare the copolyamides with high molecular weight and with the content of low-molecular compounds comparable with that of pure PA 6. Melting temperatures of the copolyamides are lower in comparison with PA 6 and decrease proportionally to the amount of the nylon salt. The thermal stability of the copolyamides is good and equal to that of PA 6. The melting enthalpies indicate that the process of crystallization of the copolyamides is influenced by the time of crystallization and the amount of comonomer present. Longer time of the crystallization assures higher degree of crystallization. The kinetics and the level of crystallization are positively influenced by the mobility of copolyamide segments mainly up to 10 wt.% of comonomer.     

Quick analysis of composition of semi-aromatic copolyamide via 13C NMR study

Standard high resolution ¹³C NMR spectra of PA10T, PA6T, PA106, and PA66 were obtained by a nonacidic solvent mixture of HFIP and CDCl₃. Several chemical shifts were found extremely sensitive to the polyamide type. According to the standard spectra, semi-aromatic copolyamides comprising PA10T, PA6T, PA106, and PA66 units could be distinguished. The ratio of each polyamide component in the copolyamide was determined through the integration of the methylene carbon peak associated with the amine group. ¹³C NMR analysis results were consistent with the theoretical values and copolyamide hydrolysis test results, making ¹³C NMR analysis quite reliable on the quick composition analysis of semi-aromatic copolyamides. Based on this technique, several commercial semi-aromatic copolyamides were further examined and their compositions were easily determined.     

Thermotropic copolyamides from triethyleneglycol bis (4-carboxyphenyl) ether,aromatic diamines,and p-aminobenzoic acid

It is proposed that depression of the transition temperatures, especially the melting point (T_m), can be achieved by the introduction of a different amide bond structure into the copolyamides of dicarboxylic acids and diamines by copolymerization of aminocarboxylic acids, such as p-aminobenzoic acid. The effect was examined by the amount and distribution of the structure in the copolylamindes. Copolycondensations of PEG₃, p-aminobenzoic acid, and diamines with different chain lengths showed that the structural change of the amide bond in the copolymers, especially its distribution, was more important than its total amount in them. Several types of aminocarboxylic acids were briefly examined to study the effect. © 1994 John Wiley & Sons, Inc.     

Chain Multiplication of Fatty Acids to Precise Telechelic Polyethylene

Starting from common monounsaturated fatty acids, a strategy is revealed that provides ultra‐long aliphatic α,ω‐difunctional building blocks by a sequence of two scalable catalytic steps that virtually double the chain length of the starting materials. The central double bond of the α,ω‐dicarboxylic fatty acid self‐metathesis products is shifted selectively to the statistically much‐disfavored α,β‐position in a catalytic dynamic isomerizing crystallization approach. “Chain doubling” by a subsequent catalytic olefin metathesis step, which overcomes the low reactivity of this substrates by using waste internal olefins as recyclable co‐reagents, yields ultra‐long‐chain α,ω‐difunctional building blocks of a precise chain length, as demonstrated up to a C₄₈ chain. The unique nature of these structures is reflected by unrivaled melting points (T _m=120 °C) of aliphatic polyesters generated from these telechelic monomers, and by their self‐assembly to polyethylene‐like single crystals.     

Synthesis of multifunctional copolyamides with both cyclobutane ring and conjugated double bond in the main chain

Copolyamides 1,9 , and 10 containing both cyclobutane rings and conjugated double bonds in the main chain were synthesized by polycondensation of 1,3-di(4-piperidyl)propane (DPP) with β-truxinate (β-BNPT), with di(p-nitrophenyl) p-phenylenebis(acrylate) (p-NPDA), with di(p-nitrophenyl) p-phenylenebis (α-cyanoacrylate) (p-NPDC), and with di(p-nitrophenyl) p-phenylenebis (α-cyanobutadienecarboxylate) (p-NPDCB) in aprotic polar solvents at room temperature, respectively. Reduced viscosity of copolyamide 1 was strongly affected by the reaction process, the molar ratio of two ester monomers, and reaction time. The copolyamide 1 with the highest viscosity was prepared by the reaction of DPP with 70–50 mol % of β-BNPT for 24 h followed by the polycondensation of the resulting precursor with 30–50 mol % of p-NPDA for 24–96 h. Although copolyamide 9 with high viscosity was not obtained by the polycondensation with β-BNPT and p-NPDC, copolyamide 10 with relatively high viscosity was obtained by the reaction with β-BNPT and p-NPDCB under the same conditions applied for the synthesis of copolyamide 1 . The solubility of copolyamides 1,9 , and 10 decreased gradually with increasing p-NPDA, p-NPDC, and p-NPDCB units in the copolymers. Furthermore, it was found that copolyamides 1,9 , and 10 crosslinked upon irradiation with 313 or 365 nm light, and these copolyamides also decomposed upon irradiation with 254 nm light. That is, the photochemical property of these copolyamides can be controlled by the selection of wavelength of the photoirradiation.     

Colloid-chemical properties of sodium and calcium salts of α-alkyl-substituted dicarboxylic acids

Surface activity and micelle formation ability in aqueous solutions of Na and Ca salts of α-alkyl-substituted dicarboxylic acids was studied in relation to the length of the hydrocarbon radical, total length of the hydrocarbon chain of the molecule, and mutual position of carboxy groups. The results obtained are compared with properties of saturated monocarboxylic and unsaturated oleic acids.     

Synthesis of an essentially alternating,aliphatic copolyamide

An essentially alternating copolyamide of 6-aminohexanoic acid and 11-aminoundecanoic acid was obtained by the condensation polymerization of methyl 11-(6-aminohexanamido)undecanoate. The monomer was synthesized by the following reaction steps: (1) nitration of cyclohexanone to α-nitrocyclohexanone; (2) cleavage of α-nitrocyclohexanone by methyl 11-aminoundecanoate to obtain methyl 11-(6-nitrohexanamido)undecanoate; (3) hydrogenation of the nitro group of the cleavage product. The polymer was characterized by its melting and crystallization behavior as determined by differential scanning calorimetry, by x-ray analysis, and by comparison with an equimolar, random copolyamide of the two amino acids.     

Polyamides from α,ω-oxaalkanedioic acids having long methylene chain units

Three series of polyamides were prepared from diamines (hexamethylenediamine, bis-5-aminoamyl ether, p-xylylenediamine) and α,ω-oxaalkanedioic acids of formula HOOC(CH₂)_mO(CH₂)_nCOOH, where m = n = 3–10, in symmetric structures, but m = 3 or 4 in unsymmetric structures. The melting points of these polymers were plotted against the number of carbon atoms of the oxaalkylene groups. The melting points of polymers from each diamine fell on three different curves according to the structures of the dicarboxylic acids: symmetric ? (CH₂)_nO(CH₂)_n? ; unsymmetric ? (CH₂)₃O(CH₂)_n? , and unsymmetric ? (CH₂)₄O(CH₂)_n? . A minimum melting point is observed at about the same point of the acid structure in every curve of the unsymmetric dicarboxylic acids. The marked depression in the polymer melting points around the minimum point is attributed to the increase of the entropy of fusion.     

Modification of PP fibres with alkaline copolyamides

Copolyamides with 5.9‐19.7 wt.% of nylon salt ADETA (adipic acid + diethylenetriamine) and 94.1‐80.3 wt.% of ϵ‐caprolactam were synthesized and their properties were estimated. Blended polypropylene/copolyamides fibres containing 5‐15 wt.% of copolyamides were prepared and their properties were evaluated. The electrical properties, hydrophilicity and especially dyeability of modified PP fibres are positively influenced by a higher amount of the copolyamide in the PP and also by a higher amount of the nylon salt ADETA in the copolyamide.     

Pervaporation Properties of Film and Composite Membranes Based on an Interpolyelectrolyte Complex of Sulfonate-Containing Aromatic Copolyamide

Film and composite membranes with a separating layer based on an interpolyelectrolyte complex of polyethylenimine and copolyamide, synthesized from isophthaloyl dichloride and two diamines, 4,4′-(2,2′-disulfonate sodium)diaminodiphenyl and 4,4′-(2,2′-disulfonate sodium)diaminodiphenylethylene, were prepared. Their mass-exchange properties in pervaporation separation of a water–isopropanol mixture were studied. The relationship between the degree of conversion in the interpolymer reaction and composition of the interpolyelectrolyte complexes, on the one hand, and membrane characteristics, on the other hand, was revealed. The interpolyelectrolyte complexes of nonstoichiometric composition, enriched in the sulfonate-containing aromatic copolyamide, show the highest performance in pervaporation separation of water–alcohol mixtures. The infl uence of the copolyamide composition on the separation characteristics of the membranes was considered. Combination of good mechanical and mass-exchange properties allows the sulfonate-containing aromatic copolyamides to be classed with promising polyanion components for interpolyelectrolyte complexes used in hydrophilic pervaporation.     

Polyesters by lipase-catalyzed polycondensation of unsaturated and epoxidized long-chain α,ω-dicarboxylic acid methyl esters with diols

Long-chain, symmetrically unsaturated α,ω-dicarboxylic acid methyl esters (C₁₈, C₂₀, C₂₆) were obtained by the catalytic metathetical condensation of 9-decenoic, 10-undecenoic, and 13-tetradecenoic acid methyl esters, respectively, with the homogeneous Grubbs catalyst bis(tricyclohexyl phosphine) benzylidene ruthenium dichloride dissolved in methylene chloride. The dicarboxylic acid esters were epoxidized chemoenzymatically with H₂O₂/methyl acetate with Novozym 435^®, an immobilized lipase B from Candida antarctica. Polyesters from symmetrically unsaturated or epoxidized α,ω-dicarboxylic acid methyl esters with 1,3-propanediol or 1,4-butanediol, respectively, were achieved by enzymatic polycondensation with the same biocatalyst applied. With 1,3-propanediol as a substrate, the linear unsaturated and epoxidized polyesters had molecular weights of 1950–3300 g/mol and melting points of 47–75 °C, whereas with 1,4-butanediol as a substrate, the resulting polyesters showed higher molecular weights, 7900–11,600 g/mol, with similar melting points of 55–74 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1601–1609, 2001     

Thermotropic copolyamides from triethylene glycol bis(4-carboxyphenyl) ether and o-tolidine modified by kinking monomers

Copolymers of triethylene glycol bis(4-carboxyphenylether) (PEG₃), 4,4′-diamino-3,3′-dimethylbiphenyl (o-tolidine, OT), and several kinking comonomers of dicarboxylic acids and diamines were prepared to investigate which of the comonomers is more effective to lower melting points (T_ms) and clearing temperatures (T_is) of the resulting thermotropic copolyamides. In general, diamine modifiers were more effective than dicarboxylic acid ones even having the same chemical structures. All of diamines examined depressed their transition temperatures linearly with the modifier content whereas the dicarboxylic acid modifiers yielded copolymers having different profiles. m-Aminobenzoic acid, another type of comonomer producing the polyamide of the AB structure, was also examined. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 363–368, 1999     

Oxidation of alcohols by electrochemically regenerated nickel oxide hydroxide. Selective oxidation of hydroxysteroids

Primary alcohols, α,ω-diols and secondary alcohols are easily transformed into carboxylic acids, dicarboxylic acids or ketones, respectively, by heterogeneous oxidation with nickel oxide hydroxide electrochemically regenerated at a nickel hydroxyde electrode. The results are discussed in comparison to those of the nickel peroxide and chromic acid oxidation. The oxidation rate decreases with increasing steric hindrance of the alcohol, thus allowing the selective oxidation of the 3-position in hydroxysteroids.     

Electrochemical polymerization of dicarboxylic acids—VI. Mechanism of polymerization

The mechanism of the electrochemical polymerization of dicarboxylic acids in various solvents, which also leads to the formation of various side products, is discussed. The formation of hydrocarbons was rationalized through the formation of α,ω-biradicals which suffer coupling or disproportionation reactions. Carboxylic acids are shown to originate from reactions of ^•(CH₂)_k COOH radicals which couple radicals which couple or disproportionate among themselves or other radicals to give saturated and unsaturated acids. Cations formed from anodic oxidation of the radicals are the precursors of lactones and some olefins. The conformations of the dicarboxylate anions at the anode surface are discussed with a view of rationalizing the formation of the various products. Polymer formation was explained as occurring through α,ω-biradicals having a definite conformation. Pyridine affected to a large extent these conformations, and higher concentrations of pyridine led to an increase in the conformations which lead to polymer formation.