Study and explanation about the morphological,electrochemical and structural properties of differently synthesized polypyrrole

Polypyrrole (ppy), a conducting polymer was synthesized by four different polymerization methods viz. electrochemical polymerization (EP), interfacial polymerization (IP), chemical oxidative polymerization (COP) and template-assisted polymerization (TAP). The change in morphology that occurred due to the variation of polymerization method used was studied with scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The samples were analyzed by Fourier transform infrared (FT-IR) spectroscopy to confirm the successful polymerization of pyrrole to polypyrrole with the appearance of characteristic bands for N–H stretching, C–N stretching, ppy ring stretching, C–H and C–C bending vibrations. Optical studies were done by UV–Vis absorption spectroscopy that displayed π→π^* and polaronic/bipolaronic transitions of ppy. XRD analysis revealed amorphous nature of ppy. Examination of SEM micrographs disclosed that ppy synthesized by EP had the typical cauliflower structure while ppy formed by IP were in the form of chain like network with a thickness of 250–290 nm, COP resulted in the formation of interlinked microspheres of polypyrrole and TAP formed polypyrrole nanofibers. Electrochemical characterization showed that ppy prepared by EP had the lowest redox activity and the samples were also tested to detect Pb²⁺.     

Synthesis and characterization of diamide–diimide–diamines based on p‐amino benzoic acid and their curing and thermal behavior with epoxy blends containing phosphorus/silicon in the main chain

Diimide–diacid ( I ) having an imide group in its rigid structure was synthesized by the refluxing of 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride [4,4′‐carbonyldiphthalic anhydride (BTDA)] and p‐amino benzoic acid in a mixture of acetic acid and pyridine (3 : 2 v/v). The chloroderivative of the diacid ( I ) was synthesized by its reaction with thionyl chloride, this was followed by condensation with different diamines with phenyl, naphthyl, ether, sulfide, and cardo groups to generate a series of diamide–diimide–diamines (DADIDAs). The resultant DADIDAs were characterized by elemental analysis and spectroscopic techniques, namely, Fourier transform infrared spectroscopy and NMR spectroscopy, and were used as epoxy curing agents to impart flame retardancy to the epoxy system. Two epoxy blends (designated as ES and EP) were prepared by the homogeneous mixing of diglycidyl ether of bisphenol A (DGEBA) with 1,3‐bis(3‐glycidyloxypropyl)tetramethyl disiloxane and DGEBA with tris(glycidyloxy)phosphine oxide: each in a ratio of 3 : 2 respectively. The synergistic effect of phosphorus/silicon with nitrogen on the thermal properties of the modified epoxy system was studied. The curing behavior of the epoxy resins formulated by the reaction of stoichiometric amounts of ES/EP with the synthesized DADIDAs were determined by differential scanning calorimetry, and the thermal stabilities of the cured epoxies were evaluated by thermogravimetric analyses (TGAs) under nitrogen and air. TGA indicated that the residual weight percentage of polymers at 800°C was in the range 36.4–60.0 in nitrogen, and in air, it was up to 6.5. However, the major loss in weight in air occurred at elevated temperature; this demonstrated their potential use as flame‐retardant epoxy systems for electronic/electrical encapsulants. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of structure of aromatic imide–amines on curing behavior and thermal stability of diglycidyl ether of bisphenol‐A

The curing behavior of diglycidyl ether of bisphenol‐A (DGEBA) with aromatic imide–amines having aryl ether, sulfone, and methylene linkages was studied using differential scanning calorimetry (DSC). Six imide–amines of varying structure were synthesized by reacting 1 mol of naphthalene 1,4,5,8‐tetracarboxylic dianhydride (N) or 4,4′‐oxodiphthalic anhydride (O) with excess (>2 mol) of 4,4′‐diaminodiphenylether [E] or 4,4′‐diaminodiphenyl methane [M] or 4,4′‐diaminodiphenyl sulfone [S]. The imide–amines prepared by reacting O or N with S, M, and E have been designated as OS/NS; OM/NM, and OE/NE, respectively. Structural characterization of imide–amines was done using FTIR, ¹H NMR, ¹³C NMR, and elemental analysis. The curing behavior of DGEBA in the presence of stoichiometric amount of imide–amines was investigated by recording DSC scans. A broad exothermic transition was observed and the peak exotherm temperature was found to be dependent on the structure of imide–amines. The peak exotherm temperature (T_p) was lowest in case of imide–amines OE and highest in case of imide–amines NS/OS. Thermal stability of isothermally cured DGEBA in the presence of imide–amines was evaluated by dynamic thermogravimetry. The char yield was highest for resin cured with imide–amines NE. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of phosphorus containing aromatic poly(amide-imide)s copolymers for high temperature applications

A series of novel thermally stable poly(amide-imide)s (PAIs) based on non-coplaner diimide-diacid (DIDA) monomer is synthesized. These polymers are characterized by elemental analysis, FT-IR, ¹H-NMR, ¹³C-NMR and ³¹P-NMR spectroscopic techniques and their physical and thermal properties are also studied. Four different dianhydrides pyromellitic anhydride (PMDA)/3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA)/1,4,5,8-naphthalene tetracarboxylic dianhydride (NTDA)/4,4′-oxydiphthalic anhydride (ODPA) and amino acid l-tryptophan are used to synthesize DIDA. The polymerization of DIDA with phosphorus containing triamines having phenyl moieties gives poly(amide-imide)s. The synthesized polymers are obtained in high yield and possessed inherent viscosity in the range 0.66–0.98 dL/g. These polymers display higher solubility in polar aprotic solvents, such as DMSO, NMP and DMF. In addition, the absorption edge values (λ _o) obtained from their UV curves are determined, and all the resulting poly(amide-imide)s films exhibited high optical transparency. The glass transition temperature (T _g) of these polymers is recorded in the range 211–265 °C, initial decomposition temperature in excess of 435 °C and char yield at 800 °C in nitrogen ranged from 52 to 70 %. Wide angle X-ray diffraction showed that all the polymers are almost amorphous.     

Preparation and morphological,thermal, and physicomechanical properties of polypropylene‐potato peel biocomposites

Potato peel powder (POPL), which is biodegradable, has been used as filler material in polypropylene (PP) matrix in varying concentration from 10 to 40% by weight to prepare biocomposites and investigated water absorption, physicomechanical and thermal properties. Scanning electron microscopy and X‐ray diffraction has been used for morphological characterization and crystallization studies. Flexural modulus of biocomposites increased by 40% compared with neat PP at 30% loading of POPL. Flexural strength also increased with increasing filler loading. Tensile strength of biocomposites has been observed to be comparable with neat PP up to 20% filler loading and increase in tensile modulus up to 40% was seen in biocomposites with 20% filler loading. Impact strength of biocomposites up to 20% filler loading was found to be at par with neat PP. Use of MA‐g‐PP compatibilizer in the biocomposites yielded better physico‐mechanical and thermal properties than biocomposites without compatibilizer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42445.     

Poly(3-hexylthiophene)/hexamine modified ZnO hybrid nanocomposite: structural,optical, thermal and electrical transport studies

This paper reports the synthesis of poly(3-hexylthiophene) (P3HT)/HA@ZnO nanocomposite by in situ polymerization and demonstrates their thermal, morphological and optoelectronic properties. Zinc oxide (ZnO) nanoparticles were prepared by the simple approach of co- precipitation method using zinc acetate dihydrate as precursor modified by hexamine (HA) acting as a capping agent. Structural and photo physical studies shows that conjugated polymer chains intimately contact with the inorganic semiconductor. ZnO has wurtzite structure with average crystallite size of 40 nm. The emission spectra indicate that modified ZnO nanoparticles results in more efficient photo induced charge transfer than that of the simple nanocomposite of P3HT/ZnO. The morphological studies revealed that the transformation of granular morphology of P3HT to the clusters in P3HT/HA@ZnO hybrid nanocomposites. Cyclic voltammeter elucidates the electrochemical behavior and the HOMO–LUMO energy levels of the nanocomposites. The results indicate that the P3HT/HA@ZnO nanocomposite has energy gap of 0.72 eV, indicating this composite has potential for the fabricating hybrid organic–inorganic solid state solar cells. A solar to electric energy conversion efficiency of 0.1238 % was attained with the system.     

Performance evaluation of different macrophytes in small-scale vertical flow constructed wetlands for greywater treatment using principal component analysis

The scarcity of water is perceived as a systematic global risk due to increasing water demand. Vertical flow constructed wetland (VFCW) is proposed as an energetically efficient and economical process to treat greywater (GW) for non-potable purposes. Macrophyte contributes a significant amount to the treatment process, and it depends on species, and their ecology. In this study, four single-stage VFCW systems were planted with locally available plant species named Hymenocallis littoralis as Plant 1, Phragmites australis as Plant 2, Canna indica Plant as 3, and Colocasia as Plant 4, which were used for the treatment of GW. The mean removal efficiencies associated with Plant 1, Plant 2, Plant 3, and Plant 4 are 55.13%, 48.11%, 52.53%, and 56.39% for chemical oxygen demand (COD); 45.35%, 35.36%, 64.10%, and 56.39% for ammonia; and 32.97%, 20.85%, 71.57%, and 33.40% for phosphate, respectively. All systems show significant removal efficiency (more than 40%) of all pollutants, except TDS and pH. Among all the observed plants, C. indica achieved the highest removal efficiency for COD, ammonia, and phosphate. The obtained results were analyzed for the dependency of correlations with effluent, influent, and macrophytes used in the treatment system. The principal component analysis (PCA) identified two principal components from 13 variables and explained 50.25%, 47.47%, and 45.62% variance of normalized datasets in VFCW. The PCA also shows significant correlations of plant species with different targeted effluent parameters.