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espanolGecarcinus quadratus es un cangrejo terrestre depredado por algunas especies, sin embargo, hay poca informacion en el nivel de genero y especie de sus predadores. Esta nota cientifica presenta el primer registro de Aramides cajaneus depredando a G. quadratus. La observacion ocurrio durante el dia, en mayo del 2021, en Costa Rica y contribuye al conocimiento sobre la historia natural, comportamiento y la ecologia de estas especies. portuguesO Gecarcinus quadratus e um caranguejo terrestre predado por algumas especies, no entanto, ha pouca informacao sobre o genero e o nivel de especies de seus predadores. Esta nota cientifica apresenta o primeiro registro de Aramides cajaneus predando o G. quadratus. A observacao ocorreu durante o dia, em maio de 2021, na Costa Rica e contribui para o conhecimento sobre a historia natural, o comportamento e a ecologia dessas especies. EnglishGecarcinus quadratus is a land crab preyed upon by some species, but there is little information about the genera and species of these predators. This scientific note presents the first record of Aramides cajaneus preying upon G. quadratus. This observation occurred during daylight in May 2021 in Costa Rica, and contributes to the knowledge about the natural history, behavior and ecology of these species.

Some features of hydrogen bonding effects for the phenylon polymer matrix filled with a terlon fiber have been investigated at ab initio approximation. The results of calculations for isolated and dimerized structural forms of N-phenylbenzamide as a model compound are in good agreement with the spectral data for this composite material building.

A taxonomic review of the Grey-necked Wood-Rail Aramides cajaneus remarked on a “previously unnoticed” parapatric distribution of this species with respect to Slaty-breasted Wood-Rail Aramides saracura. It was postulated that the two might act to exclude each other and that this isolating mechanism might have driven the evolution of a coastal species A. avicenniae Stotz, 1992. Here we demonstrate that Grey-necked and Slaty-breasted Wood-Rails are widely sympatric in Paraguay (a portion of the species range that was not discussed by the authors) and propose that this pattern probably extends to other areas of the species range too. We consider that the theory of parapatry between both species is an artefact of insufficient data, and that any proposed evolutionary processes based on that theory thus require re-evaluation.

This research was partially funded by a grant to EHCO from CNPq (307382/2019-2) and to MAFS from the Wellcome Trust in support of the Cambridge Resource Centre for comparative genomics Federal University of Par?. Post-Graduation Program in Genetics and Molecular Biology. Bel?m, PA, Brazil / Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Laborat?rio de Cultura de Tecido e Citogen?tica. Ananindeua, PA, Brasil / Cambridge Resource Centre for Comparative Genomics. Cambridge, UK. Cambridge Resource Centre for Comparative Genomics. Cambridge, UK / Federal University of Rio Grande do Sul. Pos-Graduation Program in Genetics and Molecular Biology. Porto Alegre, RS, Brazil. Cambridge Resource Centre for Comparative Genomics. Cambridge, UK. Cambridge Resource Centre for Comparative Genomics. Cambridge, UK. Cambridge Resource Centre for Comparative Genomics. Cambridge, UK. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Laborat?rio de Cultura de Tecido e Citogen?tica. Ananindeua, PA, Brasil / Federal University of Par?. Faculty of Natural Sciences. Institute of Exact and Natural Sciences. Bel?m, PA, Brazil. Abstract: Gruiformes is a group with phylogenetic issues. Recent studies based on mitochondrial and genomic DNA have proposed the existence of a core Gruiformes, consisting of five families: Heliornithidae, Aramidae, Gruidae, Psophiidae and Rallidae. Karyotype studies on these species are still scarce, either by conventional staining or molecular cytogenetics. Due to this, this study aimed to analyze the karyotype of two species (Aramides cajaneus and Psophia viridis) belonging to families Rallidae and Psopiidae, respectively, by comparative chromosome painting. The results show that some chromosome rearrangements in this group have different origins, such as the association of GGA5/GGA7 in A. cajaneus, as well as the fission of GGA4p and association GGA6/GGA7, which place P. viridis close to Fulica atra and Gallinula chloropus. In addition, we conclude that the common ancestor of the core Gruiformes maintained the original syntenic groups found in the putative avian ancestral karyotype

We report the chemistry and properties of two new series of well-defined nano sized spheres aramides-containing N- and O-naphthyl-s-triazines. The polymers were carefully characterized by different...

The synthesis and properties of novel aromatic poly- and co-polyisopthalamides bearing –OH, -tert-butyl (TERT) and 3,5-bis(trifluoromethyl) benzoyl (BTFB) groups are reported. All synthesized aramides are highly soluble in aprotic solvents, thermally stable up to 400 °C and present good film forming ability. The combination at random of -OH group with TERT or BTFB groups in copolymers CPA 1 and CPA 2 is highly effective for improving gas permeability ( P ) for all tested gases (CO 2 , O 2 , N 2 , CH 4 ) and selectivity (α) for CO 2 /CH 4 and CO 2 /N 2 . Copolymer CPA 2b containing OH and BTFB groups exhibited high gas permeability and good selectivity (P CO2 =60.17 and P CH4 =2.67, α=22.53) in comparison with analogous polyamides and some polyimides. These results are well correlated with both the increase in fractional free volume (FFV) and interchain d -spacing.

We revise the distribution and habitat associations of Aramides cajaneus avicenniae, a localised Brazilian form of the widespread Gray-necked Wood-Rail, and provide data on its foraging and breeding behaviors. This rail is a mangrove specialist endemic to the coastal belt from Sao Paulo to Santa Catarina, with some insular populations off the northern coast of Sao Paulo. Crabs, especially Uca spp., are the main prey in mangroves while island birds feed on large ground-dwelling arthropods and scavenge fish dropped by seabirds. Breeding is tied to the rainy season and nests found in mangrove sites were built with twigs and leaves on trees overhanging rivers and tidal channels and had 1-6 eggs.

Aramides cajaneus (Statius Müller, 1776) Records. Table 3. The road-killed Grey-necked Wood-rail individuals were identified by size (Wc = 18.8 cm ± 0.4; n = 2), shape, and color pattern. The upperparts were greenish dark-brown, the head and neck were grey, blending into a brown patch at the back of the head; the periocular ring was red; the bill was yellow with a greenish pit. The chest and flanks were rufous; the belly, rump and tail were black. The legs were red., Published as part of Fischer, Wagner, Faria de Godoi, Raquel & Conceição Paranhos Filho, Antonio, 2018, Roadkill records of reptiles and birds in Cerrado and Pantanal landscapes, pp. 845-876 in Check List 14 (5) on pages 869-870, DOI: 10.15560/14.5.845

The increasing concern over the waste reduction and health hazards associated with the use of synthetic fibers such as glass fibers, carbon fibers, aramides and other fibers have turned the attention towards natural ecofriendly green fibers. In this paper natural fibers namely – milkweed fiber, agave americana fiber and sansevieria roxburghiana fibers have been studied experimentally to determine the physical, chemical, morphological and thermal properties by FTIR, SEM, PLM, X-Ray Diffraction, DSC and TGA analysis methods. In this study, Sansevieria fiber was observed to have the highest tenacity of 53.58 g/tex and showed maximum degradation temperature of 375 oC. Milkweed fibers were found to have the lowest density of 0.9 g/cc and possessed hollow structure with smooth surface as observed from SEM and PLM techniques.

The introduction of fluorescent moieties in the polymeric chain permits the preparation of luminescent materials with potential applications. In this report, a number of aromatic nanosized polyamides containing both pendant acetoxynaphthamide and acetoxybenzamide were synthesized and characterized. The nanosized polymers were obtained as well-separated spherical and/or ring-shaped forms based on the pendent structure and the average diameter was 130 nm. Structure-properties correlations based on changing either the diamine and/or the pendent group demonstrated interesting connections. The polymers exhibited two major thermal decompositions attributed to the breakage of the main amide chain and the residual diacid-containing pendant moieties, respectively. Noteworthy, no significant change in the absorption spectra was noticed on phenylene / pyridine unit interchange.

Producing macrocyclic mesogens that are responsive to guest encapsulation presents a significant challenge. Cyclo[6]aramides, a type of macrocycle with a hydrogen-bond-constrained backbone, exhibit thermotropic lamellar, discotic nematic, hexagonal, and rectangular columnar mesophases over a considerably wide temperature range, including at room temperature. Additionally, cyclo[6]aramides show unusual mesophase transitions from lamellar to hexagonal columnar phase mediated by macrocyclic host-guest (H-G) interactions between the macrocycles and alkylammonium salts. The phase transition, triggered by an organic guest engaging in H-G interactions with a macrocyclic cavity, provides a novel strategy for manipulating the properties of liquid-crystalline materials. The crystal structure of a homologous cyclo[6]aramide reveals a disk-shaped, near-planar molecular backbone that facilitates intermolecular π-π stacking and leads to columnar assembly.

The taxonomy of the polytypic and wide-ranging Gray-necked Wood-rail, Aramides cajaneus is reviewed, based on external morphology and voice. Throughout its distribution, there is extensive plumage variation, much of it taxonomically uninformative. However, through three informative plumage characters, as well as morphometric and vocal variation, three phylogenetic species were identified within what is today known as Aramides cajaneus, all of which already had available names: Aramides albiventris Lawrence, 1868, from southern Mexico to northeastern Costa Rica, Aramides cajaneus (Statius Müller, 1776) (sensu stricto), from southwestern Costa Rica to Argentina, and Aramides avicenniae Stotz, 1992, from a small section of the coast of southeastern Brazil. Aramides albiventris presents extensive plumage variation, but with no geographic structure. The song of Aramides cajaneus and Aramides avicenniae is strikingly and completely different from the song of Aramides albiventris. A previously unnoticed parapatric pattern of distribution of Aramides cajaneus and its congener Aramides saracura in southeastern Brazil is described, and we clarify that the name Aramides plumbeicollis, included in the synonymy of Aramides albiventris, was first made available in 1892, rather than in 1888 as is widely referred. In addition, plumage variation in Aramides ypecaha, Aramides wolfi, and Aramides mangle is discussed.

The non-aggregational cyclo[6]aramide has demonstrated 2:1 host–guest complexation towards diquat with very strong binding ability (K1 = 5.41 × 104 M− 1, K2 = 4.33 × 106 M− 1). The donor–acceptor binding process of the macrocycle and the quaternary salt was investigated by 1H NMR, ESI mass spectrometry and UV–vis spectroscopy. The binding mode is supported by both experiments and theoretical simulations. This work provides the first example of using recently developed H-bonded aromatic oligoamide macrocycles for binding diquat in solution.

Regional, intratropical avian migrations have rarely been studied. Here, we employ an occurrence records review and ecological niche modeling tools to test the hypothesis that an understudied Neotropical bird, the Little Wood-Rail (Aramides mangle, Rallidae), seasonally migrates between the humid Atlantic coast and the dry Caatinga biome of interior northeastern Brazil. We divided records geographically between coastal and inland, and temporally between wet/breeding and dry/non-breeding seasons. Coastal records peak when inland records are fewest and vice-versa, and independence between season and region in which records were made was statistically rejected. However, ecological niche modeling shows that coastal regions are suitable habitats for A. mangle year-round, and models built with records from each season were considered statistically equivalent. It seems that this species neither performs erratic, unpredictable movements nor typical avian “to-and-fro” migration. Instead, it undergoes peri...

In Europe, Miocene rails (Aves, Rallidae) are quite abundant, but their phylogenetic placement in the context of recent forms has remained elusive. Rails from the early Miocene of the Saint-Gerand-le-Puy area in central France were first described in the 19th century, and currently, only two species are recognized, namely Palaeoaramides christyi and Paraortygometra porzanoides. Our examination of the material however suggests the presence of four, likely coeval, species of rail from these deposits. Palaeoaramides eximius, previously synonymized with Palaeoaramides christyi, is here shown to probably be a distinct species, and a previously unrecognized rail, Baselrallus intermedius gen. et sp. nov., is described. To find out how these fossil rails are related to modern Rallidae, we compared them with an extensive sample of extant rails and identified plesiomorphic and derived features for crown group Rallidae. Our assessment does not support a particularly close relationship of either Palaeoaramides to Aramides or Paraortygometra to Crex (Ortygometra), and overall, these fossil rails are more primitive than previously assumed. Based on our observations of the morphology of the previously undescribed humerus of Palaeoaramides, we show this taxon to be outside crown group Rallidae, and perhaps closely related to the early Oligocene taxon Belgirallus. On the other hand, Paraortygometra porzanoides bears a resemblance to recent flufftails (Sarothrura spp.) in some elements, but whether it can be included in a clade together with flufftails is uncertain.

A new diamine containing pyridine and carbazole groups was synthesized via a Chichibabin reaction and subsequent reduction; this compound was then used in the preparation of organo-soluble aramides (PA-a–i). The resultant polymers had high glass transition temperatures, which fell within the ranges of 271–287 °C, and Td10 at 510–535 °C in a nitrogen atmosphere. The pristine PA-a exhibited the maximum value in the UV–vis absorption spectrum at 307 nm, and this value shifted to 394 nm after protonation by HCl. When the emission of the polymer in THF solution was observed, the intensity of the emission peak at 420 nm decreased and the intensity of a new emission peak at 552 nm increased as the acid concentration increased. Additionally, the color of the polymer solution changed from blue to yellow after protonation. The intensity of the emission at 552 nm based on excimers increased as MeOH content increased. The color of polymer films also changed irreversibly from yellow, which was indicative of the neutra...

Dense membranes were prepared from three different rigid block copolyaramides, one block bearing two bulky hexafluoro (–CF3) groups and a lateral tert-butyl group (–C–(CH3)3), and the second block without the lateral tert-butyl group. The effect of block length, at constant comonomer concentration, on thermal properties as well as gas permeability coefficients and separation factors is analyzed. The results indicate that block copolyaramide membranes present a density that is quite similar but slightly lower, as the length of the blocks that form the copolymer increase, that falls in between the density of the homopolyamides. The fractional free volume, FFV, increases in the block copolymers as the block length increases. This result is attributed to an inefficient packing of the copolymer molecules as the block length gets larger. As a result, the permeability and diffusion coefficients in the block copolymers are larger than those in the parent homopolymers. The gas separation factors remain with a minimum change even though there is a gain in gas permeability; therefore, block copolymerization using highly rigid blocks, due to differences in packing, presents the advantage of a higher gas permeability coefficient with a minimum loss in selectivity. The rigidity of these copolymers presents advantages for high temperature applications.

Square planar Pd (II) and octahedral Pt (IV) complexes with novel spherical aramides nanoparticles containing flexible linkages ligands have been synthesized and characterized using analytical and spectral techniques. The synthesized complexes have been tested for their antimicrobial activity using Kirby-Bauer disc diffusion method. The antitumor activity has been performed using liver carcinoma (HEPG2), breast carcinoma (MCF7) and colon carcinoma (HCT 116) cell lines. Palladium complexes of polyamides containing sulfones showed the highest potency as antibacterial and antifungal agents. Platinum complexes containing sulfone and ether flexible linkages and chloro groups exhibited high potency as antitumor and antimicrobial agents. The uniform sizes of these nanomaterials could find biological uses such as immune assay and other medical purposes.

The importance of macrocyclic shape-persistency in novel host–guest systems for the highly efficient template-directed synthesis of rotaxanes has been revealed., Examples of using two-dimensional shape-persistent macrocycles, i.e. those having noncollapsible and geometrically well-defined skeletons, for constructing mechanically interlocked molecules are scarce, which contrasts the many applications of these macrocycles in molecular recognition and functional self-assembly. Herein, we report the crucial role played by macrocyclic shape-persistency in enhancing multipoint recognition for the highly efficient template-directed synthesis of rotaxanes. Cyclo[6]aramides, with a near-planar conformation, are found to act as powerful hosts that bind bipyridinium salts with high affinities. This unique recognition module, composed of two macrocyclic molecules with one bipyridinium ion thread through the cavity, is observed both in the solid state and in solution, with unusually high binding constants ranging from ∼1013 M–2 to ∼1015 M–2 in acetone. The high efficacy of this recognition motif is embodied by the formation of compact [3]rotaxanes in excellent yields based on either a “click-capping” (91%) or “facile one-pot” (85%) approach, underscoring the great advantage of using H-bonded aromatic amide macrocycles for the highly efficient template-directed synthesis of mechanically interlocked structures. Furthermore, three cyclo[6]aramides bearing different peripheral chains 1–3 demonstrate high specificity in the synthesis of a [3]rotaxane from 1 and 2, and a [2]rotaxane from 3 via a “facile one-pot” approach, in each case as the only isolated product. Analysis of the crystal structure of the [3]rotaxane reveals a highly compact binding mode that would be difficult to access using other macrocycles with a flexible backbone. Leveraging this unique recognition motif, resulting from the shape-persistency of these oligoamide macrocycles, in the template-directed synthesis of compact rotaxanes may open up new opportunities for the development of higher order interlocked molecules and artificial molecular machines.

Supervisor:金子 達雄, マテリアルサイエンス研究科, 修士

This chapter gives the details of various synthetic fibres (both organic and inorganic such as glass, carbon, aramides, polyolefins, ceramic fibres, etc.) used to reinforce composite materials for conventional as well as very high-tech applications. Production and properties of these fibres and also the most common applications in fibre reinforced composites are included in this chapter.

We report the preparation of thermally stable spherical sulfonated aramides nanoparticles and their copper(II) complexes. Metal chelation with copper ions furnished polymeric complexes in a 1 : 2 ratio with square planar geometries as judged by their IR, UV, electron spin resonance, and elemental analysis data. The direct-current electrical conductivities demonstrated the semiconducting nature of the polymeric particles and their copper complexes. Dielectric loss analysis studies showed spectral peaks appearing at characteristic frequencies, which suggested the presence of relaxing dipoles in all of the polymers. All loss peaks were shown on a linear frequency scale and appeared in the range of 1 decade, and no overlap was observed in any of the samples, whereas in the normal polymer's dielectric loss behavior, each peak covered more than 1 decade. Moreover, the peak positions did not change with increasing temperature; this indicated a nonactivated process. The reported dielectric results revealed anomalous behavior, which has not been reported before for such polymeric analogues, as the polarization in these cases was limited by nonthermal forces, and a steady-state constant polarization was produced by an applied field. A simple method for the formation of a microporous semiconducting thin film of a polymer derived from isophthalic acid and diaminodiphenylsulfone is described. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

We report the chemistry of nanometer-sized spherical aramides nanoparticles and their copper complexes as novel types of hybrids nanomaterials. Based on the flexible linkage type, the average diameters of the nanoparticles-containing sulfone or ether linkage were 140 nm and 190 nm, respectively, as judged by the scanning electron microscopy (SEM) photographs. Incorporation of copper (II) ions into these particles furnished polymeric complexes in (1:2) ratios with square planar geometries. The polymeric structures were proved on the basis of their IR, UV, ESR and elemental analysis data. The thermal properties of the polymers were evaluated by various techniques and results revealed the high thermal stabilities of the hybrids. The calculated limiting oxygen index (LOI) indicates that such macromolecules can be classified as self-extinguishing polymers. The dc electrical conductivity of all samples indicates either semi-conducting or metal-like nature in the regime of semiconductor behaviors. Incorporation of copper significantly improved the conductivity of the resulting complexes due to the enhanced mobility of the charge carriers upon doping. Dielectric losses are characterized by sharp peaks appearing at characteristic frequencies suggesting the presence of relaxing dipoles. The peak positions did not change with temperature indicating a non-activated process. The loss tangent increased with frequency and the peaks shifted toward the lower frequency upon doping suggesting the increase in the energy loss ratio compared to the energy storage in the dielectric. The higher value of dielectric loss at low frequency is due to the free charge motion within the materials. The reported dielectric results revealed anomalous behaviors which have not been reported earlier in similar hybrids.

Three block copolymers have been prepared by reacting two rigid polyaramide blocks, a high gas permeability rigid poly(hexafluoroisopropylidene-5- tert -butylisophthalamide), HFA/TERT block and a barrier aramide poly(benzophenone isophthalamide), DBF/ISO block. Blocks of each aramide were prepared by synthesizing two prepolymers by condensation and combining them to obtain the block copolyaramides, HFA/TERT-b-DBF/ISO, with different block lengths 9:9, 12:12 and 18:18 average repeating units on each block. Thermal and dynamic mechanical properties were measured. The onset of decomposition for these copolymers is above 480 °C with weight losses below 10 wt% at 500 °C. tan δ for the copolyaramides shows two transitions: one for the DBF/ISO block and the other corresponding to HFA/TERT block. DBF/ISO has very low gas permeability coefficients which are at least one order of magnitude below those of HFA/TERT. The block copolyaramides show permeability coefficients slightly lower than those of HFA/TERT well described by a parallel arrangement of block microdomains. They also show similar separation factors or an increase of them above those of the HFA/TERT homopolymer. It was found that shorter block segments (vg. HFA/TERT-b-DBF/ISO 9) present lower permeability coefficients than those with larger (HFA/TERT-b-DBF/ISO 18) block segments without an appreciable loss in selectivity for gas pairs O 2 /N 2 and CO 2 /CH 4 which are the industrial interest separations expected for these block copolymers, and O 2 /N 2 ideal separation factors are better than those found in other copolymers with flexible polymer blocks.

We report the preparation of narrow-sized well-separated spherical aramides nanoparticles containing pyridine using the precipitation polymerization method. The average diameter of the particles ranges from 50–98 nm. Particles of pyridine containing polymers exhibited large diameter compared to their phenylene counterpart. Symmetric meta-polymers showed relatively higher ηinh and thermal stability and thus higher degree of polymerization than their nonsymmetrical counterparts. Incorporation of Copper (II) ions into these polymers furnished copper-polymer complexes in a (1:2) ratio and the reported structures are proposed on the basis of their IR, UV, ESR and elemental analysis data. The ERS spectra of the complexes exhibited typical axial spectra with g// and g⊥ features and the data indicated that the copper site has a dx2-y2 ground state, characteristic of square planar or elongated octahedral stereochemistry. The incorporation of copper into aramides backbones significantly improved their optical and t...

Cyclic aromatic oligoamides are a new class of recently discovered shape-persistent macrocycles. These molecules are prepared in high yields based on a one-step macrocyclization strategy that relies on hydrogen bond-enforced folding of the corresponding uncyclized oligomeric precursors. Macrocycle 1 is a member of a series of six-residue macrocycles dubbed cyclo[6]aramides and bears polar side chains derived from tri (ethylene glycol) monomethyl ether. We investigated its self-assembly using multiple techniques including UV-Vis spectrum, dynamic light-scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Results from these experiments demonstrated that 1 aggregates in apolar solvents such as 1, 2-dichloroethane. As temperature increases, the supramolecular aggregates gradually disintegrate into molecularly dissolved species. For example, at 70 ℃, compound 1 exists mainly in its molecularly dissolved form. In mixed solvents consisting of good (dichloromethane) and poor (aromatic hydrocarbons) components, compound 1 aggregates into spherical assemblies. These self-assembling spheres were shown by studies on thermal stability and by TEM imaging to be solid balls instead of hollow vesicles. The formation of the microspheres was found to be dependent on the properties of the poor solvents as their formation was promoted in aromatic hydrocarbons and obliteratedin aliphatic and polar solvents. In aliphatic and polar solvents, macrocycle 1 was found to assemble into films.

Aromatic polyamides find many applications in diverse and critical areas due to their high thermal stability coupled with high mechanical properties. However most of such aramides are difficult to fabricate because of their limited solubility and high melting temperature. Improvements in processability have been reported by incorporating bulky pendant groups and aliphatic spacer groups. Similarly to improve the solubility of polymers approaches of incorporating silicon in main polymer chain and co-polymerization techniques were useful. We report the synthesis and characterization of a series of phenylated silicon containing aromatic–aliphatic polyamides from a mixture of 2, 5-bis (4-carboxy methylene phenyl)-3, 4-diphenyl thiophene (CMPDT) and bis-(4-carboxy phenyl) dimethyl silane (BCPDS) in various mole proportions, with commercial aromatic diamine. Thus a series of novel co-polyamides having pendant phenyl groups, methylene spacer and silicon moiety was prepared by judicious combination of (CMPDT); BCPDS and aromatic diamine; bis-(4-aminophenyl) ether (ODA), by direct polycondensation using Yamazaki’s phosphorylation method. These high molecular mass polyamides were obtained in high (89–98%) yields and had viscosities in the range of 0.23–0.57 dL/g in DMAc. Polyamides showed improved solubility in polar aprotic solvents, like NMP, DMAc, DMSO and DMF; had high thermal stability; with no mass loss below 335 °C.

The local dynamics of aromatic cores was analyzed for a homologous series of polyamides in the solid phase incorporating phenyl, biphenyl and naphthyl groups. Preliminary wide-line and spin-relaxation variable-temperature 1 H NMR measurements revealed the presence of thermally activated molecular motions for each polymer studied. A number of 13 C NMR experiments were then implemented to further clarify the nature and extent of such motions. These included 1 H– 13 C 2D separate-local-field measurements, whose line shapes revealed that motions involved for all cases a superposition of states. These could in principle be associated with rigid and mobile populations in these semi-crystalline aramides, a model that yielded a proper description of the spectra at all temperatures. To further probe this model the relaxation behavior of the aramides’ 13 C spins was monitored in the rotating frame as a function of temperature, in both the presence and absence of homonuclear 1 H– 1 H decoupling. The variations observed in these measurements evidenced a thermally activated, relatively broad distribution of motional rates in the polymers. Editing the 2D local-field data according to the 13 C relaxation also supported this heterogeneous dynamic model. The mechanism underlying this behavior and implications towards the 13 C analysis of motions in aramides in particular and complex polymers in general, is briefly discussed.

A number of low molecular weight sulfonated aromatic compounds: carboxamides, imides, sulfonamides, as well as sulfonated polymers; aramides and poly(styrene-p-sulfonic acid), were tested for their stability on heating in water and dilute acid to temperatures ranging from 130–200 °C. Desulfonation was observed with some compounds. Sulfonamide linkages were found to be stable, while carboxamide linkages and phthalimides were not.

Macrocyclizations in exceptionally good yields were observed during the self-condensation ofN-benzylated phenylp-aminobenzoates in the presence of LiHMDS to yield three-membered cyclic aramides that adopt a triangular shape. Anortho-alkyloxy side chain on theN-benzyl protecting group is necessary for the macrocyclization to occur. Linear polymers are formed exclusively in the absence of this Li-chelating group. A model that explains the lack of formation of other cyclic congeners and the demand for anN-(o-alkoxybenzyl) protecting group is providedon the basis of DFT calculations.High-resolution AFM imaging of the prepared molecular triangles on a calcite(10.4) surface shows individual molecules arranged in groups of four due to strong surface templating effects and hydrogen bonding between the molecular triangles.

A unique supramolecular two-component gelation system was constructed from amphiphilic shape-persistent cyclo[6]aramides and diethylammonium chloride (or triethylammonium chloride). This system has the ability to discriminate native arginine from 19 other amino acids in a specific fashion. Cyclo[6]aramides show preferential binding for the guanidinium residue over ammonium groups. This specificity was confirmed by both experimental results and theoretical simulations. These results demonstrated a new modular displacement strategy, exploring the use of species-binding hydrogen-bonded macrocyclic foldamers for the construction of two-component gelation systems for selective recognition of native amino acids by competitive host–guest interactions. This strategy may be amenable to developing a variety of functional two-component gelators for specific recognition of various targeted organic molecular species.

A strategy of using amide groups as the only functionality was developed to construct convergent heteroditopic cyclo[6]aramides that are able to strongly bind dibutylammonium chloride in chloroform (10(5) M(-1)), leading to the formation of [2]pseudorotaxanes.

Several branched and dendritic aromatic amides have been obtained by reacting tris(4-aminophenyl)methane 3 either with aryl iodide 1 in a Pd-catalysed carbonylation or with carboxylic acids in the presence of the coupling agent triphenyl phosphite. Nonpolar aromatic substituents and solubilising groups at the periphery ensured that the resulting oligoamides were soluble in chloroform, whereas amide groups in the structural centre of the molecules accounted for strong self-association through hydrogen bonding in solution as evidenced by 1H NMR and vapour-pressure osmometry data. An alternative approach towards branched aramides is also presented which was based on the self-assembly of 1,3,5-tris(4,5-dihydroimidazol-2-yl)benzene 12 and various (amido)carboxylic acids.

A modern technique for a controlled surface modification of synthetic fibres consists of irradiation with a pulsed UV laser, which can be used to execute submicrometre surface treatment on polymers. Many types of synthetic fibres, e.g. poly(ethylene terephthalate), polyamides and aramides, show a characteristic surface modification when irradiated by ArF and KrF lasers. The originally smooth surface of these fibres changes its morphology to a rather regular roll-like structure perpendicular to the fibre axis after this treatment. A phenomenological report on the dependence of structure formation on polymer and laser conditions is given. © 1997 SCI.

Multiring diamines and diacids containing ether and isopropylidene or hexafluoroisopropylidene bridges between phenyl groups were used alone or together with 1,4-phenylenediamine and terephthalic acid to prepare flexible or semirigid aromatic polyamides by direct polycondensation using triphenyl phosphite and pyridine as condensing agents. All the polyamides are readily soluble in N,N-dimethylacetamide, N-methyl-2-pyrrolidone and N,N-dimethylformamide. The wholly flexible polyamides are completely amorphous whereas those prepared from 1,4-phenylenediamine or terephthalic acid are partially crystalline and melt in the temperature range from 276 to 330°C. Thermal analysis shows Tg's in the range from 204 to 216°C for the wholly flexible polyamides and in the range from 239 to 257°C for the semirigid ones. Both classes of aromatic polyamides show excellent thermal resistance which is comparable with that of rigid-rod aramides.

Finite temperature simulations of the crystalline phase of the aromatic polyamides poly(p-phenyleneteraphthalamide) IPPTA) and poly(p-benzamide) (PBA) are carried out self-consistently using a molecular mechanics force field for the interatomic potential and quasi-harmonic lattice dynamics for the vibrational free energy. The calculated thermal expansion coefficients agree well with the experimental values. The negative axial thermal expansion in these aramides is attributed to elastic coupling to the transverse thermal stresses and to a lesser extent to an increase in entropy associated with contraction

The reduction pattern of PdCl 2 supported on oligomeric aramides has been investigated by temperature programmed reduction (TPR) measurements in the range of temperature −80 to 305°C. The influence both of chemical composition of the oligomeric matrix and Pd loading has been ascertained. A peculiar metal—support interaction greatly affects the reducibility of Pd, allowing its stabilisation in the oxidised form (i.e., Pd 2+ ).

Methanesulfonic acid (MSA) is often employed as a solvent for high-performance polymers such as poly-(p-phenylene-cis-benzobisoxazole) or PBO, aramides, and conducting polymers. Since MSA is highly hygroscopic, and water has very strong effects on the physicochemical properties of the acid, it is important to develop methods to control and assess its composition. An approach involving the use of methanesulfonic anhydride (MSAA) is presented. The properties and compositions of MSAA solutions in MSA were investigated by combining 1 H NMR, conductimetry, viscometry, and differential refractometry. The results showed that previous studies involving MSA polymer solutions, and reported physical properties of MSA, were affected by water contamination

Results on polycondensation of poly(1.4 benzamide) (PBA) and 2.5.DCIPDAcoTPA in solutions of poly(vinylpyrrolidone) (PVP) will be presented. For polycondensation, the method of OGATA, using triphenylphosphine and hexachloroethane, and the low-temperature solution polycondensation of dicarboxylic acid dichlorides and diamines, were applied. It is shown that the molar mass of PBA depends strongly on the PVP:PBA ratio. To explain this dependence, one has to take into account the phase behavior of the ternary rigid rod polymer/flexible coil polymer/solvent system and the influence of the matrix polymer. An enhancement of the molar mass of the PBA produced can be observed when the PVP:PBA is high enough to prevent an association of the PBA, i.e. when one stays in the isotropic one-phase area of the phase diagram. Under these circumstances, it is possible to obtain one-phase systems in nonsolvents for the aramides.

Recently it has been shown that the creep of oriented high-modulus fibers satisfies a logarithmic time law over very long time intervals. Moreover, the modulus of these fibers increases due to the creep. This was interpreted by the annihilation of conformation defects during creep. In structures with strong intermolecular interactions as in aramides, however, the direct annihilation of defects is difficult to explain. Moreover a direct annihilation leads to a false time law if no further assumption about the properties of the defects are made. In this paper a model for the transport of conformation defects in oriented polymer chains imbedded into an oriented fibrillary structure with strong intermolecular interactions is presented. This modified transport model leads directly to the experimentally observed time law without any further assumptions about the defect properties.