Synthesis of hydrophilic polyamide from L-tartarate and diamines by active polycondensation

Dimethyl L-tartarate underwent polycondensation reaction with hexamethylenediamine in solutions at 30°C to form polyamide having pendent hydroxyl groups. Solvents had a great influence on polymer yields and diglyme, tetrahydrofuran (THF) or dimethylsulfoxide (DMSO) were favorable in respect of polymer yields. Solution viscosities of resulting polyamide were as low as 0.1 to 0.2. However, post-polycondensation of the precursor polyamide at solid phase yielded hydrophilic polyamide having film-forming ability. The polyamide decomposed at 210°C by heating.     

Conformational energies of para-aromatic and aryl-aliphatic polyamides: Relation to mesogenic character in solution

PCILO conformational calculations have been carried out on several model compounds of aromatic polyamide oxamides and polyamide hydrazides. The comparison of the entropy of the equilibrium conformations allows a classification of the various constitutive units into “rigid” segments, and “flexible” ones having respectively low or high entropies. From the results, it is possible to predict the mesogenic nature of solutions of a large number of aromatic polyamides, polyamide hydrazides, and polyamide oxamides.     

末端带有溴甲基基团的柱状树枝化聚酰胺的合成与表征

采用大分子单体的方法合成了一种含大量溴甲基官能团端基,主链和侧链均为聚酰胺的功能化柱状树枝化聚酰胺.氯化亚砜的新活化工艺使整个合成过程不需要保护和去保护的步骤且减少了副反应的产生,从而使得合成和纯化更加简单.产物的结构通过红外和核磁得到了证实.由分子量测试知,聚酰胺的重均分子量(Mw)为5.01×104,分子量分布为2.74.由溶解性测试知,该聚合物能溶解于N,N′-二甲基甲酰胺、N,N′-二甲基乙酰胺、二甲亚砜、1-甲基-2-吡咯烷酮和硫酸等溶剂,溶解性能得到了大大的提高,主要是由于侧链树枝化单元和末端溴甲基存在的缘故.由粘度测试知,该聚酰胺的粘度低,主要是由于侧链树枝化单元的屏蔽效应.该聚合物的热性能也由TGA测试得到了表征,结果表明该聚酰胺具有良好的热性能.由于该聚酰胺外端具有大量的溴甲基基团,它可以作为原子转移自由基聚合反应的引发剂来合成大型的梳形聚合物,另外通过把它外围的溴甲基转化为其它的功能化基团,可以使它应用于其它更广的领域.     

DSC Studies on Melting and Crystallization of Polyamide 6/Biopol Blends

Blends obtained from Biopol D600G and polyamide 6 reveal in DSC investigations multiphase structure with a distinct crystalline polyamide 6 phase. Due to rapid crystallization of the polyamide 6 the crystallization of the Biopol D600G is retarded. The grade of crystallization of Biopol D600G is lower in the blends than in the pure state, as calculated from the melting enthalpies. Crystallization of polyamide 6 in the blends is faster and results in increasing of the grade of crystallization of polyamide 6 phase comparing to the unblended component. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and in Vitro Cytotoxicity of a Novel Conjugate of Polyamide and Phospholipid

Small molecules with the ability to target predetermined sequences of DNA would be valuable tools in molecular biology and potentially in human medicine1-3. Synthetic polyamides consisting of N-methylpyrrole (Py), N-methylimidazole (Im) have received spec…     

Morphology and properties of ternary polyamide 6/polyamide 66/elastomer blends

The aim of the work presented is to evaluate the mechanisms and phase interactions in ternary blends based on different polyamides and functionalised elastomers, and to establish a correlation between the morphology controlled by the specific binary interactions, and physical and technological properties, respectively. The properties of the ternary system polyamide 6/polyamide 66/ elastomer depend on the specific blend morphology which is determined mainly by the differences of the surface tension of the components. A phase‐in‐phase structure was observed by microscopic study (AFM) in the ternary polyamide 6/polyamide 66/elastomer blends with maleic anhydride grafted ethene‐octene copolymer, and a “quasi” phase‐in‐phase structure in blends with maleic anhydride grafted ethene‐propene‐diene copolymer as the elastomer phase. An incorporation of polyamide inside of the elastomer particles was observed in the first case due to the difunctionality of polyamide 66. This type of morphology causes an increased elongation at break and toughness of these blends. In comparison to the binary polyamide based blends the ternary blends show an increased elastic modulus, elongation at break and yield stress as well as a high impact strength at low temperatures up to ?20 °C. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis of a Pair of Derivatives of N-Methylpyrrole Polyamide

A pair of derivatives of tetrameric N-methylpyrrole polyamide were synthesized in order to develop a new method for the study of interaction of the polyamide derivatives with DNA. Indole acetic acid and nicotinic acid were introduced to the polyamide in the synthesized compound, which showed an expected red shift in the UV spectrum. These compounds may function as a potential tool in the detection of the polyamide binding to DNA.     

Postcondensation and oxidation processes in molten polyamide 6

Polyamide samples were heated under vacuum or mixed in a Brabender plastograph. UV absorbance, chain end concentration, and molecular weight were studied. Postcondensation was observed for polyamide heated under vacuum. For polyamide samples mixed in the plastograph, atmosphere, shear rate, and temperature changed. Melt viscosity and intrinsic viscosity are in good correlation in a log-log plot. Oxidation effect on molecular weight and amine chain end concentration could be well related to UV absorbance. The oxygen diffusion into the molten polyamide is a critical parameter. The oxygen concentration in the polyamide mixed under air is ca. 20 times higher than when mixed under nitrogen. The introduction of preoxidized material in the molten polyamide or mixing in the presence of oxygen have similar effects. Postcondensation and oxidation strongly influence the melt behavior of polyamides. © 1993 John Wiley & Sons, Inc.     

The reciprocal influence between ion transport and degradation of PA66 in acid solution

Transport behavior of acid solution through polyamide was studied by measuring element distribution in cross section, pH, and ion concentration. Degree of degradation that related to the decreasing of molecular weight and flexural strength was observed in order to study the influence of acid solution on the polyamide 66 (PA66) degradation. The permeation mechanism of acid solution can be explained: at first water penetrates into polyamide and it is followed by acid. In this process, water does not affect the molecular weight at 50 °C but only reduces the polyamide strength by plasticization. Moreover, proton (H⁺) has contributed to the anion transport and degradation of polyamide by the hydrolytic reaction. Proton attacks the polyamide chain, and scission of chain occurs, and reacts with anion to form other material substance. This process affects the decrease of molecular weight and the significant loss of polyamide strength. Analysis results from ion concentration measurement shows that the amount of proton and anion transport into deionized waterside was imbalance, which probably due to the different mobility between proton and anion or formation of other material substance by reaction of anion and PA66 bond. Such information is not only necessary for the investigation of hydrolytic degradation of polymer and prediction of lifetimes for a protective polymer lining/coating to chemical attack, but may also be helpful towards gaining a deeper insight into the processes of degradation of other polymer.     

Ab initio calculation of the Young's modulus of α‐polyamides

In earlier works the supermolecule model has been applied to the calculation of the Young's modulus of crystalline polyethylene and polyamide‐6. In the supermolecule model a crystalline polymer is represented as a single finite chain divided into a head, body, and tail part. The body contains a number of monomer units and is representative for a polymer chain. In this article, this model has been used to study the geometric properties and the elastic moduli of the α form of other polyamides: polyamide‐2 (or polyglycine), polyamide‐3, polyamide‐4, polyamide‐11, and polyamide‐6,6. All calculations have been performed with a linearly constrained body. The results have been compared to other theoretical and experimental results if available. © 2002 Wiley Periodicals, Inc.; DOI 10.1002/qua.2002;10121     

Synthesis of block copolymer containing dextran and polyamide sequences

A novel AB-type block copolymer composed of dextran and polyamide sequences was prepared through the following two approaches. One is a coupling reaction of a terminal functional group introduced in the dextran chain with that in the polyamide chain, such as the reaction of an amine group with an acyllactam group or that of a lactone group with an amine group at the corresponding chain ends. The other is an anionic polymerization of a bicyclic lactam activated with a trimethylsilylated dextran derivative having an acyllactam end group. The latter procedure was found to be more effective for the preparation of the block copolymer having a high molecular weight polyamide sequence.     

Structural and Kinetic Profiling of Allosteric Modulation of Duplex DNA Induced by DNA-Binding Polyamide Analogues

A combined structural and quantitative biophysical profile of the DNA binding affinity, kinetics and sequence-selectivity of hairpin polyamide analogues is described. DNA duplexes containing either target polyamide binding sites or mismatch sequences are immobilized on a microelectrode surface. Quantitation of the DNA binding profile of polyamides containing N-terminal 1-alkylimidazole (Im) units exhibit picomolar binding affinities for their target sequences, whereas 5-alkylthiazole (Nt) units are an order of magnitude lower (low nanomolar). Comparative NMR structural analyses of the polyamide series shows that the steric bulk distal to the DNA-binding face of the hairpin iPr-Nt polyamide plays an influential role in the allosteric modulation of the overall DNA duplex structure. This combined kinetic and structural study provides a foundation to develop next-generation hairpin designs where the DNA-binding profile of polyamides is reconciled with their physicochemical properties.     

Isothermal and nonisothermal crystallization kinetics of novel odd-odd polyamide 9 11

A study on isothermal and nonisothermal crystallization kinetics of odd-odd polyamide 9 11 was carried out by differential scanning calorimetry (DSC). The equilibrium melting temperature of polyamide 9 11 was determined to be 199.1 °C. The Avrami equation was adopted to describe isothermal crystallization of polyamide 9 11. Nonisothermal crystallization was analyzed using both the Avrami relation modified by Jeziorny and the equation suggested by Mo. The isothermal and nonisothermal crystallization activation energies of polyamide 9 11 were determined to be −310.9 and −269.0 kJ/mol using the Arrhenius equation and the Kissinger method, respectively.     

New nonlinear optical polyamides: Influence of binding mode of side-chains and rigidity of main-chains on temporal stability

New nonlinear optical rigid polyamides were synthesized and the influence of the binding mode between nonlinear optical chromophores and oxybutyl spacers, as well as of the rigidity of the main-chain on the second-order nonlinearity were investigated. The polyamides with side-on binding mode exhibit higher temporal stability of the polar order than analogous polyamide with end-on binding mode. By decreasing the rigidity of the main-chain of side-on polyamides, polyamide with 4,4’-methylenedianiline reveals enhanced solubility and processability, still keeping a high temporal stability compared to the relatively rigid polyamide with 1,4-phenylenediamine.     

Syntheses of aromatic polyketones and aromatic polyamide

High molecular weight aromatic polyketones were prepared from p- and m-phenoxybenzoic acid in polyphosphoric acid by heating the reaction mixture at 100°C. High molecular weight aromatic polyamide was derived from the polyketone obtained through Schmidt reaction or Beckmann rearrangement. The polyamide obtained by Schmidt reaction was found to have some regularity in an arrangement of its repeating units. The thermal stability of the polyketone and the polyamide were good.     

Overview and critical survey of polyamide6 structural habits: Misconceptions and controversies

Various aspects of the structural habits and associated thermodynamic properties of polyamide6 are critically examined with regard to controversies that appeared in literature mainly due to misconceptions or erroneous/ambiguous interpretations of experimental findings. The structural habits under concern are the crystallization capabilities and chain topology, hydrogen bonds and sheet-like structure, crystalline polymorphism together with thermodynamic stability. Thermo-mechanical properties are also discussed for the sake of complementary argumentation. Comparisons are made with polycaprolactone, that is, the polyester homolog of polyamide6 regarding chain structure, in order to evaluate the actual role of the H-bonds on the structural habits. Additional comparisons with polyethylene and polypropylene are also made at several occasions for the sake of supporting argumentation on the structural behavior of polyamide6. A temperature–time–transformation diagram of polyamide6 is finally proposed from the gathering of plentiful literature data.     

Soluble aromatic polyamide bearing ether linkages: synthesis and characterization

Soluble aromatic polyamide chains were prepared by reacting 4–4′-oxydianiline with isophthaloyl chloride in dimethylacetamide. To quench the HCl produced during the polymerization reaction, a stoichiometric amount of triethylamine was added. The precipitates formed were separated leaving behind clear polyamide resin. Thin and transparent film was obtained by evaporating the solvent and was subjected for Fourier transform infrared (IR), nuclear magnetic resonance (NMR), gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, water absorption, and mechanical analyses. The transparent film was found to be soluble in dimethylacetamide, dimethyl sulfoxide, and dimethylformamide. IR and NMR spectroscopic analyses confirmed the structure of the polyamide while the gel permeation chromatography revealed the formation of a high-molecular-weight polymer. Thermogravimetry, differential scanning calorimetry, water absorption, and mechanical testing were also performed to further verify its physical properties. A soluble aromatic polyamide was successfully synthesized by solution polymerization and characterized. The polyamide has film-forming property, and the film is transparent, mechanically strong, and thermally stable.     

Hot-melt adhesives based on polyamides of dimerized fatty acids and adhesive compositions from oligoamidoamines and epoxy resins

The production and the application of hot-melt adhesives and adhesive compositions based on polyamide and the oligoamidoamine derivatives of dimerized fatty acids are studied. The possibility of synthesizing basic polyamide thermoplasts with desired physicochemical properties is shown.     

The effect of fiber coating on the tensile properties of ionomer-based composites

Asbestos fibers, of the chrysotile variety, were coated with a thin polyamide film by an in situ polycondensation technique. Ionomer-based composites were prepared containing the so-modified asbestos fibers in a random in-plane orientation; results of testing the tensile properties of these asbestos/polyamide/ionomer composites are presented. Parameters investigated comprise the asbestos content in the composite and the polyamide content deposited on asbestos. A significant improvement in the tensile performance was established, especially at the intermediate polyamide content of 3.4 phr. The behavior is discussed in terms of possible interactions between the phases present in the composite material.     

Synthesis of saccharide-conjugated polyamides by quasi-living anionic polymerization of a bicyclic lactam

Several well-defined graft copolymers ( 7 ) having a water-soluble natural polysaccharide (dextran) stock and hydrophilic polyamide branches of different molecular weights were synthesized by using a quasi-living anionic polymerization of a bicyclic lactam 1 , namely by the reaction of the acyllactam group in the quasi-living polyamide 2 with the hydroxyl and amino groups in the dextran derivative ( 6 ), of which the reducing end was converted to an amino group. An oligosaccharide-terminated polyamide 3 was also prepared efficiently by similar coupling reaction of the corresponding quasi-living polyamide 2 , with the maltose derivative ( 5 ) having an amino group. © 1994 John Wiley & Sons, Inc.