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Oligomeric poly(amide)s (PAs) were synthesized from monomeric diacids, which were obtained from phthalic anhydride and the amino acid glycine, l-alanine, l-phenylalanine, l-valine, l-leucine, l-isoleucine and p-aminobenzoic acid. The phthalimidyl acids (IA-1 to IA-7) reacted with 5-amino-isophthalic acid in order to obtain the monomeric diacids (1-7). Furthermore, the monomeric diacid 8 was obtained by direct reaction between phthalic anhydride and 5-amino-isophthalic acid. The isophthalic acid derivatives were reacted with bis(4-aminophenyl)diphenylsilane in order to obtain the PAs. Monomers and polymers were characterized by infrared and 1H-, 13C- and 29Si-NMR spectroscopy, elemental analysis and, when necessary, optical rotation. The results were in agreement with the proposed structures. The yields were generally good, but the ηinh values were low, indicating that the polymers were of oligomeric nature, namely, a chain of moderate molecular weight. The polymers were soluble in polar aprotic solvents and some of them were soluble in m-cresol and tetrahydrofuran. The glass transition temperatures (Tg) values were obtained by differential scanning calorimetry, showing, in general, a decrease in value when the volume of the side chain of the amino acid moiety was increased. The thermal stability of the polymers was determined by dynamic thermogravimetry, showing good values of thermal decomposition temperatures (TDT), especially for those with aromatic residue in the amino acid, and for PA without amino acid. For PAs in which the side chain of the amino acid was larger, the TDT values were lower, probably due to the lack of symmetry and the length of the side chain, both of which have influence on the thermal stability. [ABSTRACT FROM AUTHOR]

Copolymerization reactions involving N-vinylimidazole and its derivatives have stimulated great interest due to the wide possibilities of the preparation of new materials, including the synthetic analogues of biopolymers with imidazole fragments. The role of the imidazole group in polymers is very important, especially due to the high thermal stability at elevated temperatures when it is copolymerized with methacrylates, which contain highly electronegative atoms like oxygen [10,11]. Accordingly, copolymers of N-vinylimidazole with phenoxy- and methoxyethylmethacrylate have been prepared and subjected to thermogravimetric analysis to discover their thermal stability. Copolymers are also characterized by FTIR and 1H-NMR spectroscopic methods. Results show that the thermal stability is greater for N-vinylimidazole-co-phenoxyethylmethacrylate than for those with N-vinylimidazole-methoxyethylmethacrylate. [ABSTRACT FROM AUTHOR]

Abstract: Synthesis, characterization and behavior at the air–water interface of A–B–A triblock copolymers are reported. The copolymers consist of a poly(ethylene oxide) central block and poly(ε-caprolactone) lateral blocks. The synthesis was controlled in order to obtain central and lateral blocks of variable length. Copolymer characterization was performed by FTIR and 1H NMR spectroscopy, size exclusion chromatography (SEC), and thermal analysis. Monolayers of the copolymers at the air–water interface were obtained by the Langmuir technique and the respective isotherms were obtained by monolayer compression. The limiting area per repeat unit (A o) and the critical exponent of the excluded volume (ν) for spread monolayers were obtained. The static elasticity (ε 0) of the monolayers was also determined. The obtained results allow proposing a schematic model of the orientation of the different blocks during the compression of the respective monolayers. [Copyright &y& Elsevier]

The free radical copolymerization of phenoxyethyl methacrylate (POEMA) and glycidyl methacrylate (GMA) was carried out using α,α'-azobisisobutyronitrile (AIBN) in 2-butanone solution at 333 ± 1 K. The copolymers were characterized by FTIR, 1H-NMR and 13C-NMR spectroscopic methods. Thermal properties of the copolymers were also studied by thermogravimetric analysis (TGA). The compositions of the copolymers were established by 1H-NMR analysis. The monomer reactivity ratios were computed using the Fineman-Ross (F-R) and Kelen-Tüdos (K-T) methods. These parameters were also estimated using a nonlinear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). The mean sequence lengths determination indicates that the copolymers obtained are random in nature. Differences in the reactivity ratios obtained by the classical methods and RREVM were observed. GMA is more reactive than POEMA and although the copolymers are random, some tendency to GMA small block formation is reported. [ABSTRACT FROM AUTHOR]

Abstract: The ability of solid N-alkyl quaternized poly(4-vinylpyridine) with hexyl, octyl and decyl bromide for the retention of chromate and dichromate forms of Cr(VI) in aqueous solutions is studied. The retention of Cr(VI) was investigated by batch equilibrium procedure and this study was supported by UV–vis spectrophotometry, infrared (IR) spectroscopy and thermal analysis (glass transition temperature and thermal degradation). The retention of Cr(VI) was possible in the range of concentrations between 1×10−6 and 1×10−3 mol/L and it was dependent on the length of the polyelectrolyte side aliphatic chain. Thermogravimetric analysis (TGA) indicated that solid phase, (N-alkyl quaternized poly(4-vinylpyridine), with Cr(VI) (P4VPyC8-Cr(VI)) is slightly more stable than P4VPyC8 in absence of Cr(VI). Differential scanning calorimetric (DSC) measurements indicate that the segmental movements are restricted due to the presence of chromate and/or dichromate ions in the solid phase. [Copyright &y& Elsevier]

Using solution-casting method, binary blends of chitosan (CS) and poly (ethylene oxide) (PEO 100,000) containing Au nanoparticles (AuNPs) were prepared. Shifts in the melting temperature ( T m ) and crystallization temperature ( T c ) values for CS/PEO and CS/PEO/AuNPs blends were observed by calorimetric analysis. In general, CS/PEO/AuNPs blends tended to decompose at higher temperatures than neat polymers. From the FT-IR spectra, shifts in the main signals, such as −NH 2 , −OH and C O C, were detected in the blends and were attributed to the polymer interactions and the incorporation of gold nanoparticles. In addition, the analysis of the blend topographies by atomic force microscopy (AFM) showed that at a higher CS content, more homogenous surfaces were observed. This behavior was attributed to the interactions present in the CS/PEO/AuNPs blends. Finally, theoretical analyses helped to confirm that the gold nanoparticles would be preferentially adsorbed onto the chitosan microdomains due to the interactions between acetyl and hydroxyl groups and Au atoms. [ABSTRACT FROM AUTHOR]