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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.

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.

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.

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.

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+ ).

Oligomeric aramides of the phenyleneterephthalamide structural type, impregnated with Pd salts, have been prepared and characterized. For a better understanding of the type of interactions between Pd and these oligomers, the corresponding monomeric model compound and simpler molecules have been investigated by several techniques. The results obtained establish that a coordination complex is formed through a specific linkage between Pd and the primary amino groups present as chain terminals both in the macromolecular species as well as in the model compound. No evidence has been found of significant bond interactions involving either carboxyl or secondary amido groups.