Comprehensive and Facile Synthesis of Some Functionalized Bis-Heterocyclic Compounds Containing a Thieno[2,3-b]thiophene Motif

A comprehensive and facile method for the synthesis of new functionalized bis-heterocyclic compounds containing a thieno[2,3-b]thiophene motif is described. The hitherto unknown bis-pyrazolothieno[2,3-b]thiophene derivatives 2a-c, bis-pyridazin othieno[2,3-b]thiophene derivatives 4, bis-pyridinothieno[2,3-b]thiophene derivatives 6a,b, and to an analogous bis-pyridinothieno[2,3-b]thiophene nitrile derivatives 7 are obtained. Additionally, the novel bis-pyradazinonothieno[2,3-b]thiophene derivatives 9, and nicotinic acid derivatives 10, 11 are obtained via bis-dienamide 8. The structures of all newly synthesized compounds have been elucidated by (1)H, (13)C NMR, GCMS, and IR spectrometry. These compounds represent a new class of sulfur and Nitrogen containing heterocycles that should also be of interest as new materials.     

Synthesis and Characterization of Privileged Monodentate Phosphoramidite Ligands and Chiral Brønsted Acids Derived from d-Mannitol

The synthesis of several novel chiral phosphoramidite ligands (L1–L8) with C₂ symmetric, pseudo C₂ symmetric secondary amines and chiral Brønsted acids 1a,b has been achieved. These chiral auxiliaries were obtained from commercially available d-mannitol, and secondary amines in moderate to excellent yields. Excellent diastereoselectivites of ten chiral auxiliaries were obtained. The chiral phosphoramidite ligands and chiral Brønsted acids were fully characterized by spectroscopic methods.     

Effects of functionalization conditions of sulfonic acid grafted SBA-15 on catalytic activity in the esterification of glycerol to monoglyceride: a factorial design approach

A series of propyl sulfonic acid-modified SBA-15 catalysts (SBA-15SO₃H) was prepared under various conditions using post-functionalization approach. A factorial design coupled with response surface analysis were employed to evaluate the effects of the preparation conditions on the catalyst activity. Optimization of the conditions to find the most active SBA-15SO₃H catalyst with the highest activity in glycerol esterification with lauric acid at 160?°C for 6?h was also made. Amount of 3-(mercaptopropyl)trimethoxysilane (MPTMS) and reflux time were chosen as parameters of the preparation conditions. The presence of propyl sulfonic acid groups in SBA-15SO₃H catalysts was confirmed by FT-TIR method. The catalysts were also characterized by means of surface analysis, XRD, TEM and TGA. The results obtained from the statistical models suggested that the amount of MPTMS was more important parameter to influence the activity compared to the reflux time. The optimum preparation condition was achieved at a reflux time of 20?h and an MPTMS amount of 1?mL/gram SBA-15 to obtain the SBA-15SO₃H(1) with the highest monoglyceride selectivity (70.2%) and corresponding lauric acid conversion (95%) in the esterification process.     

Influence of Single-Walled Carbon Nanotubes on the Performance of Poly(Azomethine-Ether) Composite Materials

The present work is aimed to fabricate a new set of composite materials containing conducting poly(azomethine-ether) reinforced with single-walled carbon nanotubes in the form of single-walled carbon nanotube/poly(azomethine-ether)_1–5 for excellent enhanced thermal as well as conducting behavior of poly(azomethine-ether). Single-walled carbon nanotubes of variable loading have been embedded into conducting poly(azomethine-ether) using in situ polymerization technique. Before attempting the polymerization, 1,3-thiazole established poly(azomethine-ether) and its conformable monomers have been prepared and their chemical structures have been correlated by spectral analyses. Furthermore, η_inh and M_w values for poly(azomethine-ether) were found 0.89?dL?g^?1 and 39723.6, respectively. The fabricated single-walled carbon nanotube/poly(azomethine-ether)_1–5 composites were specified and characterized by wide-angle X-ray diffraction patterns, Fourier transform infrared spectroscopy, thermal behavior, scanning electron microscopy, and transmission electron microscopy characterization techniques. A perfect indicative response for this composite material was estimated by Fourier transform infrared spectra and X-ray diffraction as well. Both techniques displayed all intensive characteristic peaks regarding single-walled carbon nanotubes and poly(azomethine-ether) in the spectra or diffraction pattern for single-walled carbon nanotube/poly(azomethine-ether)_1–5. The role of single-walled carbon nanotubes on the performance of poly(azomethine-ether) was considerably examined. Single-walled carbon nanotube/poly(azomethine-ether)_1–5 showed relatively higher thermal stability. Single-walled carbon nanotube/poly(azomethine-ether)₁ displayed the lowest final composite degradation temperature value (552°C), whereas single-walled carbon nanotube/poly(azomethine-ether)₅ displayed the highest value (621°C). T₁₀ and T₂₅ values showed a gradual temperature increased while single-walled carbon nanotubes increased. Single-walled carbon nanotube/poly(azomethine-ether)₁ showed the lowest thermal stability and single-walled carbon nanotube/poly(azomethine-ether)₅ showed the highest thermal stability between all fabricated products. Furthermore, transmission electron microscopy images showed a prominent increase in single-walled carbon nanotubes diameters (40–60?nm). The conductivity values were significantly increased while single-walled carbon nanotubes content was increased and reached to the semiconductors. ε′ values were also increased in both single-walled carbon nanotube/poly(azomethine-ether)_4,5 which have higher single-walled carbon nanotubes content.     

Compressive mechanical properties of sawdust/high density polyethylene composites under various strain rate loadings

This article is concerned with the static and dynamic mechanical properties of high‐density polyethylene (HDPE) reinforced with sawdust (SD) at a strain rate of up to 10³ s^?1. In this study, the static and dynamic properties of HDPE/SD composites with different filler loadings of 5, 10, 15, 20, and 30 wt% SD were deliberated at different levels of strain rates (0.001, 0.01, 0.1, 650, 900, and 1100 s^?1) using a conventional universal testing machine and the split Hopkinson pressure bar apparatus. The results showed that the stress–strain curves, yield behavior, stiffness, and strength properties of the HDPE/SD composites were strongly affected by both the strain rate and the filler loadings. Furthermore, the rate sensitivityof the HDPE/SD composites showed a great dependency on the applied strain rate, increasing as the strain rate increased. However, the thermal activation values showed a contrary trend. Meanwhile, for the postdamage analysis, the results showed that the applied strain rates influenced the deformation behavior of the tested HDPE/SD composites. Moreover, for the fractographic analysis at dynamic loading, the composites showed that all the specimens underwent a severe catastrophic deformation. J. VINYL ADDIT. TECHNOL., 24:162–173, 2018. © 2016 Society of Plastics Engineers     

Synthesis of poly(acrylonitrile‐co‐divinylbenzene‐co‐vinylbenzyl chloride)‐derived hypercrosslinked polymer microspheres and a preliminary evaluation of their potential for the solid‐phase capture of pharmaceuticals

Poly[acrylonitrile (AN)‐co‐divinylbenzene (DVB)‐co‐vinylbenzyl chloride (VBC)] terpolymers were synthesized by precipitation polymerization in the form of porous polymer microspheres. The poly(AN‐co‐DVB‐co‐VBC) polymers were then hypercrosslinked, via a Friedel‐Crafts reaction with FeCl₃ in nitrobenzene, to provide a significant uplift in the specific surface areas of the polymers. FTIR spectra of the hypercrosslinked poly(AN‐co‐DVB‐co‐VBC)s showed that the chloromethyl groups derived from VBC were consumed by the Friedel‐Crafts reactions, which was consistent with successful hypercrosslinking. Hypercrosslinking installed a number of new, small pores into the polymers, as evidenced by a dramatic increase in the specific surface areas upon hypercrosslinking (from ～530 to 1080 m² g^?1). The hypercrosslinked polymers are very interesting for a range of applications, not least of all for solid‐phase extraction (SPE) work, where the convenient physical form of the polymers (beaded format), their low mean particle diameters, and narrow particle size distributions, as well as their high specific surface areas and polar character (arising from the AN residues), make them attractive candidates as SPE sorbents. In this regard, in a preliminary study one of the hypercrosslinked polymers was utilized as an SPE sorbent for the capture of the polar pharmaceutical diclofenac from a polar environment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45677.     

Hollow micro-mesoporous carbon polyhedra produced by selective removal of skeletal scaffolds

An approach has been demonstrated for fabricating hollow micro-mesoporous carbon polyhedra by selective removal of the skeletal scaffolds of polyurethane (PU) foam in monolithic mesostructured resin/PU composites. Hollow micro-mesoporous carbon polyhedra with an irregular shape molded from the cellular cavities of PU foam were synthesized by using phenolic resol as a precursor, triblock copolymer Pluronic F127 as a template, PU foam as a skeletal scaffold and triethyl phosphate as a reaction agent. By a reaction with triethyl phosphate, the PU foam in resin/PU composites can be degraded, simultaneously leading to the disassembly of the monolithic structure into separated polyhedral particles. The method can also be used for synthesizing hollow micro-mesoporous carbon–silica polyhedra, using tetraethyl orthosilicate as a silica source. Moreover, after etching the silica away, hollow micro-mesoporous carbon polyhedra with an ordered hexagonal mesostructure (space group p6mm), large particle sizes of 65–500 μm, a large surface area of 1384 m² g^?1, a uniform pore size of 3.2 nm and a high pore volume of 1.15 cm³ g^?1 as well as a high mesoporosity of 81% can be obtained, which exhibits excellent adsorption performance toward methylene blue compared with the active carbon having a similar surface area.     

Effect of ambient conditions on drying of herbs in solar greenhouse dryer with integrated heat pump

An even span solar greenhouse dryer was built and applied to dry Java tea (Orthosiphon aristatus) and Sabah snake grass (Clinacanthus nutans Lindau). Findings showed that the solar greenhouse dryer performs satisfactorily during clear weather except at nighttime and rainy day due to product rehydration which is heavily influenced by high relative humidity from ambient air. Integrating of heat pump into the solar greenhouse dryer has successfully reduced the room relative humidity by 10–15%. Also, heat pump has mitigated the product rehydration issue by maintaining room relative humidity at maximum of 65% throughout the drying period. The drying rate of Java tea was improved three to fourfold, i.e., from 0.004–0.008 to 0.018–0.025?g H₂O/g DM min, whereas 10% of drying time was saved for both Java tea leaf and Sabah snake grass leaf with the assistance of heat pump system. Meanwhile, the supply of dry air from the heat pump system with a magnitude of 0.25–0.50?m/s helps in enhancing the drying rate of the herbs as well as minimizing the nonuniformity of drying temperature and relative humidity inside the solar greenhouse dryer.     

A novel polymer composite with a small optical band gap: New approaches for photonics and optoelectronics

In this article, a novel approach is presented for the preparation of small band‐gap polymer composites. The intensity of the surface plasmon resonance (SPR) peak increased from 0.64 to 3.2 for the chitosan–silver nitrate sample containing 1 wt % titanium dioxide (TiO₂). In the cases of 3 and 5 wt % added TiO₂ particles, the SPR peak disappeared. A wide shift of the absorption coefficient from 4.36 to 0.93 eV was observed. The smallest optical band gap of about 0.98 eV was achieved for the sample containing 3 wt % TiO₂ filler. The wide shift in the optical band gap was interpreted on the bases of the formation of metal‐induced gap states between the metallic silver particles and the TiO₂ structure. A novel approach was achieved that was an alternative method to Tauc's semi‐empirical model for band‐gap estimation. The optical dielectric loss parameter for the band‐gap study was easily calculated and analyzed, whereas it unfolded a deep knowledge from the physics point of view. The established quantum mechanical expression revealed a strong relationship between the energy band gap and the optical dielectric loss parameter. The scanning electron microscopy results show the leakage of white aggregated silver particles and distinguishable intense peaks of metallic silver particles between 3 and 3.3 keV appearing in the energy‐dispersive X‐ray spectrum. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44847.     

A new initiating system based on [(SiMes)Ru(PPh3)(Ind)Cl2] combined with azo-bis-isobutyronitrile in the polymerization and copolymerization of styrene and methyl methacrylate

The homopolymerization and copolymerization of styrene and methyl methacrylate, initiated for the first time by the combination of azo-bis-isobutyronitrile (AIBN) with [(SiMes)Ru(PPh₃)(Ind)Cl₂] complex. The reactions were successfully carried out, on a large scale, in presence this complex at 80 °C. It was concluded from the data obtained that the association of AIBN with the ruthenium complex reduces considerably the transfer reactions and leads to the controlled radical polymerization and the well-defined polymers.