Synthesis and rheological study of some maleic acid polyamides

The contributions of the cis and trans configurations of the main chain double bonds to the transition temperatures and rheological properties were determined for four well-defined polymaleamides, which were prepared by the room temperature ring-opening, step-growth polymerization reactions of N,N′-bisisomaleimide monomers with bifunctional primary diamines. The polymaleamides were glassy solids, which could be thermally isomerized into related polyfumaramides. The glass transition temperatures of the polyfumaramides, as determined by mechanical spectrometry, are systematically and markedly higher than those of the polymaleamides from which they were derived.     

Transition and relaxation processes in ω-amino acid polyamides

Differential thermal analysis has been used to study the thermal transitions that occur on heating efficiently quenched samples of ω-amino acid polyamides. With ‘even’ amino acid polyamides (nylons-4, -6, -8, etc.) an endothermic type of transition was observed in the region of 30–40°C; this was followed immediately by an exothermic transition. No such transitions were observed with the ‘odd’ polyamides (nylons-5, -7, -11, etc.). From X-ray diffraction spectra and structural considerations, these transitions have been shown to be associated with the formation of hydrogen-bonded structures, that are possible with ‘even’ polyamides, but not with the ‘odd’ members. From a combination of differential thermal analysis, density and X-ray diffraction data, a new picture of the low temperature crystallization behaviour of this type of polyamide has emerged.     

Hydrolytic degradation of polyamides based on L-tartaric acid and diamines

We have studied the deposition of thin films of a conducting polymer, polypyrrole, onto printed circuit boards (PCBs). Film formation occurs as a result of the in situ polymerization of pyrrole monomer using a 1 : 1 FeCl³/5-sulfosalicylic acid oxidant complex in aqueous solution. We have optimized the polymerization conditions in order to coat a large number of PCBs with a single polymerization bath, while at the same time maintaining the quality of the conducting polymer coating (i.e., keeping its surface resistance below 10⁴ Ω per square). These improvements were achieved simply by controlling the initial oxidant–monomer mole ratio such that the oxidant is always present in significant excess. We have also examined the formation of thick polypyrrole layers obtained from the progressive buildup of thin layers. The morphology and film thickness of these polypyrrole coatings have been studied by scanning electron microscopy. Some preliminary electroplating experiments using these polypyrrole–PCB composites are also described. © 1995 John Wiley & Sons, Inc.     

Synthesis of polyamides from sugar derived d-glucaric acid and xylylenediamines

d -Glucaric acid (GA) is the one of aldaric acids and is an important bio-based building block for polymers. In this study, poly(m-xylylene-acetyl glucaramide) and poly(p-xylylene-acetyl glucaramide) were synthesized from GA acetate and two kind of aromatic diamines by solution polymerization. The chemical structures of the polyamides were analyzed by nuclear magnetic resonance spectroscopy. The weight-average molecular weights ranged from 3.3 × 10³ to 1.15 × 10⁴ with a polydispersity of 1.6–1.9, depending on monomer ratio or monomer concentration in solution. The 10% decomposition temperature of the polymers was about 210 °C. Differential scanning calorimetry revealed that the polyamides exhibited no peaks attributed to crystallization or melting point, which indicated that the polyamides were amorphous. No crystalline pattern was observed in the X-ray diffractograms, supporting this result. Polarized optical microscopy observation revealed that the polyamides exhibited melting-like behavior at above 150 °C, which was attributed to glass-transition behavior. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47255.     

Crystalline structure and crystallization of stereoisomeric polyamides derived from arabinaric acid

The pair of stereoisomeric polyamides PA-6dAr and PA-6lAr, as well as the racemic stereocopolyamide PA-6dlAr was synthesized from hexamethylenediamine and 2,3,4-tri-O-methyl-arabinaric acid (d, l and their equimolar mixture, respectively). All these polyamides were aregic, thermally stable and display high crystallinity. The combined analysis by X-ray and electron diffraction revealed that the all three polyamides adopted the same crystal structure, which consists of a rhombic lattice with the chains in a highly contracted conformation capable of accommodating efficiently the sugar moiety in the space. The Avrami kinetic analysis revealed that copolyamide PA-6dlAr crystallized isothermally much slower than the optically homogeneous polyamides. A parallel study carried out on the racemic mixture of PA-6dAr and PA-6lAr evidenced that this mixture has a crystal structure and displays a thermal behavior similar to their separated components, and that its crystallization rate is intermediate between them and the racemic copolyamide PAdlAr.     

Synthesis and characterization of polyamides based on cubane-1,4-dicarboxylic acid

The direct polycondensations of cubane-1,4-dicarboxylic acid with 1,4-phenylenediamine (2 a), 4,4′-oxydianiline (2 b), 4,4′-sulfonyldianiline (2 c), and 9,9′-bis(4-aminophenyl)florene (2 d) were carried out in N-methyl-2-pyrrolidone/pyridine containing triphenylphosphite and lithium chloride at 110 °C for 9 h. Polyamide 3 a obtained from 2 a was scarcely soluble in organic solvent even during heating, and was soluble only in conc-H₂SO₄, whereas 3 c and 3 d derived from 2 c and 2 d, respectively, were readily soluble in N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethylsulfoxide. After treating polyamide 3 d with the rhodium complex catalyst in NMP, cubane units were quantitatively converted into cyclooctatetraenes. Received: 3 March 1997/Accepted: 1 April 1997     

Synthesis and characterization of some polyamides incorporating modified isophthalic acid units

Some polyamides with side chains were prepared using a direct polycondensation reaction between carboxyl groups from O‐cinnamoyl‐5‐hydroxyisophthalic acid and N‐cinnamoyl‐5‐aminoisophthalic acid and various diisocyanates in the presence of 4‐dimethylaminopyridine, as catalyst, without use of condensing agents. The polymers were characterized by elemental analysis, viscosimetry, spectroscopic and thermal measurements. © 2002 Society of Chemical Industry     

Drug delivery from nonpeptidic α-amino acid containing polyamides

New nonpeptidic α-amino acid-based polyamides were used for drug delivery. Benzocaine was covalently linked via a spacer to N-protected poly(l-cystyl-l-cystine) and to poly(adipoyl-l-lysine). Its release by α-chymotrypsin attack was followed by UV. It was nearly quantitative within two days with l-cystine-based polyamide. Protected forms of these polyamides were used as matrices. Release of benzocaine entrapped in polyamide from (l-cystine) was controlled by diffusion. When entrapped in polyamide from (l-lysine) it was controlled by diffusion and swelling. Received: 10 January 1997/Accepted: 23 January 1997     

Synthesis of some fumaric acid polyamides from active diester monomers

Summary The solution polycondensation of two active diesters, bis(2,4-dinitrophenyl) fumarate and 1,1-(fumaroyldioxy)bis(benzotriazole), with a series of alphatic and aromatic diamines in N-methyl pyrolidone at room temperature, was investigated. The polycondensation reactions yielded a series of fumaric acids polyamides. The polymers obtained from aliphatic diamines were soluble in trifluroacetic acid and exhibited well-defined melting points. The polymers obtained from aromatic diamines are infusible at temperatures below 300°C but were thermally stable and soluble in dimethylacetamide containing 4% LiC1.     

Synthesis and properties of polyamides from 2,5‐furandicarboxylic acid

The aim of this study is to investigate the synthesis of 2,5‐furandicarboxylic acid (FDCA)‐based copolyamides. Indeed, FDCA monomer may be a potential bio‐based alternative to phthalic acids. A series of polyamides and copolyamides, PA 6‐I(x)/6‐F(y), are synthesized in a pilot scale reactor by melt polycondensation of salts based on FDCA, isophthalic acid (IPA), and 1,6‐hexamethylenediamine. The chemical structure and composition of the resulting copolymers are extensively characterized by NMR (¹H, ¹³C, and 2D), MALDI‐TOF as well as size exclusion chromatography and solution viscosimetry. Their thermal properties are studied by differential scanning calorimetry and TGA and also by a molecular modeling technique. It is pointed out that, during the synthesis, FDCA‐rich polymers overcome a massive decarboxylation of FDCA, preventing the production of high molar mass polymers. It is also found that all polymers are amorphous and that the glass transition temperatures decrease as the amount of FDCA in the polymer increases. This is confirmed by the results from molecular dynamics. In addition, it is observed that the copolymers become more hygroscopic when the amount of FDCA in the copolyamides increases. However, the water uptake of PA 6‐I(x)/6‐F(y) with 90 > x > 50 is lower than those of PA6 and PA 66 polyamides. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45901.     

Synthesis, characterization and degradability of polyamides derived from tartaric acid and diaminoethers

A series of novel polyamides derived from l or d-tartaric acid and α,ω-diaminoethers containing 1, 2, 3 or approximately 70 oxyethylene units in the main chain were synthesized and characterized. Polycondensation in solution of the diaminoethers with di-O-methyl tartaric acid activated as pentachlorophenyl ester was used for the synthesis of these poly(ether tartaramide)s. Polymerization degrees oscillated between 10 and 140 depending on the length of the oxyethylene segment. These polyamides are highly hygroscopic and soluble in water. They are semicrystalline with melting temperatures ranging from 50 to 190 °C, and thermally stable up to 250 °C. Chiro-optical properties were found to depend on the configuration of tartaric acid showing both high specific rotations and characteristic circular dichroism ellipticities. Definite X-ray diffraction patterns consistent with the crystalline nature of these polyamides were recorded. Racemates made of enantiomeric pairs were also examined and some evidence indicative of the existence of a crystalline structure different from that present in the optically pure components was found.     

Synthesis and properties of polyamides and copolyamides based on 2,6-naphthalene dicarboxylic acid

A number of polyamides based on 2,6-naphthalene dicarboxylic acid (NDA) and various aromatic diamines were synthesized in N-methyl pyrrolidone (NMP) containing lithium chloride (LiCl) or calcium chloride (CaCl₂) by direct polycondensation using triphenyl phosphite and pyridine. The best reaction conditions for polycondensation were determined in terms of factors such as the amount of the solvency-promoting reagent such as LiCl or CaCl₂ and the initial reactant concentration. Thus, almost all polyamides were obtained with inherent viscosities above 1.0 and up to 3.28 dL/g. Similarly, high molecular weight copolyamides with inherent viscosities of 1.76–3.61 dL/g were prepared from 4,4′-oxydianiline (ODA) and mixed dicarboxylic acids of NDA/terephthalic acid (TPA) or NDA/isophthalic acid (IPA). The solubility of NDA homopolyamides depended on the diamine components. The polyamides derived from meta-, sulfone-, or alkylene-linked diamine showed increased solubility. Copolymerization of ODA with NDA/IPA led to a significant increase in solubility, whereas with NDA/TPA, it gave a limited improvement. All the homopolyamides and copolyamides showed an amorphous X-ray diffraction pattern. Almost all the polymers soluble in aprotic solvents can be solution-cast into strong and tough films. Glass transition shifts of some NDA polyamides can be observed in the differential scanning calorimetry (DSC) curves ranging from 243 to 345°C. Most NDA/IPA–ODA copolyamides also showed clear transitions in the range of 255–268°C. In nitrogen, all the polymers showed no significant weight loss up to 400°C, and their 10% weight loss temperatures were recorded in the range of 434–541°C. © 1994 John Wiley & Sons, Inc.     

Miscible blends of styrene-acrylic acid copolymers with aliphatic,crystalline polyamides

Styrene-acrylic acid copolymers exhibit miscibility with various aliphatic, crystalline polyamides (e.g., nylon 6, 11, and 12) at 20% acrylic acid content in the copolymer. At 8% acrylic acid, phase separation is observed with the crystalline polyamides. At 14% acrylic acid, partial miscibility is observed with each polyamide, resulting in the T_g's of the constituents shifted toward the other constituent. The miscibility of the styrene-acrylic acid copolymers ( > 14 wt % AA) can be ascribed to hydrogen bonding interactions with the polyamides. Styrene-acrylic acid (20% AA) copolymers are miscible with other nylons with alternating amide orientation along the chain (e.g., nylon 6,6 and nylon 6,9). These samples tend to crosslink upon exposure to temperatures above the polyamide melting point unlike the nylon 6, 11, and 12 blends in which branching may only occur. Nylon 11/styrene-acrylic acid blends were chosen for crystallization rate studies. A melting point depression of nylon 11 occurs with addition of the styrene-acrylic acid (20% AA). The Flory-Huggins interaction parameter from the melting point depression is calculated to be -0.27. The crystallization rate of nylon 11 is significantly reduced with the addition of the miscible SAA copolymers (20% AA). The spherulitic growth rate equation predicts this behavior based on a T_g increase with SAA addition.     

Synthesis and characterization of polyamides based on natural monomers: l-lysine and l-aspartic acid

Nonpeptidic diamine-diacid type polyamides were prepared from natural α-amino acids, l-lysine and l-aspartic acid, under mild conditions. l-lysine carboxylic group was protected as a benzyl ester; l-aspartic acid amino group was protected as benzyloxycarbonyl (Z) or t-butyloxycarbonyl (BOC) derivatives. The activated ester method provided polyamides with protected amino and carboxyl side groups. The deprotection of these side groups revealed to be perfectly selective when the amino groups were protected as t-butyloxycarbonyl derivatives. Received: 20 February 1997/Revised: 8 April 1997/Accepted: 14 April 1997     

Synthesis of fully bio-based polyamides with tunable properties by employing itaconic acid

A class of bio-based aliphatic polyamides (BDIS) was synthesized by melting copolycondensation from four biomass monomers: originated (SA), itaconic acid (IA), 1, 10-decanediamine (DD), and 1, 4-butanediamine (BD). IA was introduced into the system in order to adjust the chemical structure and the aggregation structures of the BDIS polyamide. Thus, some new polyamides with tunable properties were obtained, such as semi-crystalline polyamide with relatively low melting point, glassy polyamide with excellent toughness, and even rubbery polyamide after hydration. Some of the BDIS can be well melting spinned into fibers with comparable strength as polyamide-6. The BDIS with 100% itaconic acid can even be dissolved in ethanol, which makes it possibly be used by coating and dipping methods. In vitro cytotoxicity tests showed that these polyamides are nontoxic towards mouse fibroblasts and have great potential in biomedical applications.     

Biologically active polymers. IV. Synthesis and antimicrobial activity of tartaric acid polyamides

New bactericidal polyamides with quaternary ammonium or phosphonium salts were prepared, and their antimicrobial activities were explored. The polyamides were synthesized by the polycondensation of diethyl‐l‐tartrate or chloromethylated diethyl‐l‐tartrate with ethylenediamine in dry absolute ethanol. The polyamides were modified to yield polymers with either quaternary ammonium or phosphonium salts. The polymers were characterized with elemental microanalysis and ¹H‐NMR and IR spectra. The antimicrobial activity of the polymers bearing onium salts was studied against Gram‐negative bacteria (Escherichia coli, Pseudomones aeruginosa, Shigella sp., and Salmonella typhae), Gram‐positive bacteria (Bacillus subtilis and Bacillus cereus), and a fungus (Trichophytum rubrum) by the cut‐plug and viable‐cell‐count methods. Although all the polymers showed high antibacterial activity, some had no antifungal activity. The tributyl phosphonium salt of the polyamide was more effective against both Gram‐negative and Gram‐positive bacteria than the triethyl ammonium and triphenyl phosphonium salts of the polyamide. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4780–4790, 2006     

Functional polyamides

Summary Polymerization of azo initiators having dinitrile functions such as 2,2-azobis(isobutyronitrile) (AIBN) with formaldehyde in the presence of sulfuric acid were carried out in order to permit the synthesis of polyamides containing thermolabile azo groups.The obtained polyamides have appropriate initiating functionality for subsequent free radical polymerization.     

Preparation and properties of biobased polyamides based on 1,9-azelaic acid and different chain length diamines

Polymer Bulletin - A series of environmentally friendly polyamides (PA69, PA109 and PA129) have been synthesized by carrying out step-melting polycondensation reactions of bioderived monomers:...     

Synthesis and properties of silicon-containing polyamides

A series of aromatic polyamides incorporating silicon together with phenylquinoxaline or with hexafluoroisopropylidene groups has been synthesized by solution polycondensation of a silicon-containing diacid chloride with aromatic diamines having phenylquinoxaline rings or hexafluoroisopropylidene groups. These polymers are easily soluble in polar aprotic solvents, such as N-methylpyrrolidinone and dimethylformamide, and in tetrahydrofurane, and can be solution-cast into thin, transparent films having low dielectric constant, in the range of 3.26 to 3.68. These polymers show high thermal stability with decomposition temperature being above 400°C and glass transition temperature in the range of 236°C to 275°C. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1533–1538, 1997