Study of C centres in NaCl by positron angular correlation

The nature of C centres in NaCl has been experimentally studied by the positron annihilation technique. The results are in support of a previously proposed model for the C centres [1]. The approximate size of C centres has been estimated to be of the order 6.3 ± 0.7 Å.     

Studies on the structural,thermal and optical behaviour of solution grown organic NLO material: 8‐hydroxyquinoline

Single crystal of 8‐hydroxyquinoline (8HQ) having chemical formula C₉H₇NO, an organic nonlinear optical (NLO) material has been successfully grown by slow evaporation solution growth technique at room temperature. The crystal system has been confirmed from the powder X‐ray diffraction (PXRD) analysis. The crystalline perfection was evaluated by high resolution X‐ray diffractometry (HRXRD). From this analysis we found that the quality of the crystal is quite good. However, a very low angle (tilt angle 14 arc sec) boundary was observed which might be due to entrapping of solvent molecules in the crystal during growth. Its optical behavior has been examined by UV‐Vis. analysis, which shows the absence of absorbance between the wavelengths ranging from 400 to 1200 nm. From the thermal analysis it was observed that the material exhibits single sharp weight loss starting at 113°C without any degradation. The laser damage threshold was measured at single shot mode and the SHG behavior has been tested using Nd:YAG laser as a source. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Benzimidazole‐indole‐chalcone connected methacrylate‐based side chain D‐π‐A polymer and its application in organic photovoltaics

Herein, we report four metal‐free organic polymethacrylates (In‐In‐BzI)PMA , (Ac‐In‐BzI)PMA , (TPA‐In‐BzI)PMA , and (Py‐In‐BzI)PMA with pendant chromophores donor‐π‐conjugated‐acceptor (D‐π‐A) molecular framework as photosensitizers for dye‐sensitized solar cells (DSSCs). In which the donor‐acceptor units are attached by an indole‐chalcone extending side chain to inhibit back electron transfer and charge recombination; the π‐linker component contains varied chalcone‐based substituents to enhance the sunlight‐harvesting ability of the solar device. Photon‐current cells based on the DSSC format were fabricated using the polymers as sensitizers. The DSSC device assembled using (TPA‐In‐BzI)PMA exhibits a considerably better IPCE peak and J–V response, with an overall power conversion efficiency of 3.70% under the illumination of AM 1.5G (100 mW cm^–2). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 997–1007     

Peracetic Acid Depolymerization of Biorefinery Lignin for Production of Selective Monomeric Phenolic Compounds

Lignin is the largest source of renewable material with an aromatic skeleton. However, due to the recalcitrant and heterogeneous nature of the lignin polymer, it has been a challenge to effectively depolymerize lignin and produce high‐value chemicals with high selectivity. In this study, a highly efficient lignin‐to‐monomeric phenolic compounds (MPC) conversion method based on peracetic acid (PAA) treatment was reported. PAA treatment of two biorefinery lignin samples, diluted acid pretreated corn stover lignin (DACSL) and steam exploded spruce lignin (SESPL), led to complete solubilization and production of selective hydroxylated monomeric phenolic compounds (MPC‐H) and monomeric phenolic acid compounds (MPC‐A) including 4‐hydroxy‐2‐methoxyphenol, p‐hydroxybenzoic acid, vanillic acid, syringic acid, and 3,4‐dihydroxybenzoic acid. The maximized MPC yields obtained were 18 and 22 % based on the initial weight of the lignin in SESPL and DACSL, respectively. However, we found that the addition of niobium pentoxide catalyst to PAA treatment of lignin can significantly improve the MPC yields up to 47 %. The key reaction steps and main mechanisms involved in this new lignin‐to‐MPC valorization pathway were investigated and elucidated.     

Shape optimization for a composite crack-length sensor

Conductive polymeric sensors can be used as crack-length gages. They have the advantages of being inexpensive, versatile in size and require inexpensive instrumentation. They also measure crack length continuously. The shape of these gages can be varied in several ways to improve their sensitivity. The gages with the 'optimized' or tapered shape overcome the principal disadvantages of rectangular gages, namely poor sensitivity at small crack lengths.     

Synthesis, characterization and application of cellulose/polyaniline nanocomposite for the treatment of simulated textile effluent

The aim of the study was to analyze the potential application of cellulose/polyaniline (Ce/Pn) nanocomposite for the treatment of synthetic reactive dye bath effluent. The Ce/Pn composite was synthesized by chemical oxidative polymerization of aniline. A central composite experimental design, a most popular design of response surface methodology, was applied to optimize the level of variables, namely, cellulose and polyaniline, to get the best response on dye removal. Biological transmission electron microscopy studies reveal that the cellulose particles were uniformly distributed on the nanocomposite. The results of the batch experiment studies indicate that Ce/Pn nanocomposite removed 95.9, 91.9, 92.7, and 95.7 % of RBBR, RO, RV, and RBK, respectively, and it decolorized 82 % of dye bath effluent. However, the presence of the salts reduced the adsorption rate of the dyes. The Langmuir model and pseudo first-order rate expression exhibited satisfactory fit to adsorption data of single component.