Imide-functionalized arenes, exemplified by naphthalene diimides (NDIs), perylene diimides (PDIs), and bithiophene imides (BTIs), are the most promising building blocks for constructing high-performance n-type polymers. In order to reduce the steric hindrance associated with NDI- and PDI-based polymers and to address the high-lying LUMO issue of BTI-based polymers, herein a highly electron-deficient imide-functionalized bithiazole, N-alkyl-5,5′-bithiazole-4,4′-dicarboximide (BTzI), was successfully synthesized via an efficient C–H activation. Single crystal of BTzI model compound showed a planar backbone with close π-stacking distances (3.2–3.3 Å). The N,N′-bis­(2-alkyl)-2,2′-bithiazolethienyl-4,4′,10,10′-tetracarboxdiimide (DTzTI) was also used for constructing polymer semiconductors. Compared to DTzTI, BTzI is more electron-deficient, rendering it highly appealing for enabling n-type polymers. On the basis of BTzI and DTzTI, a series of polymers, including acceptor–acceptor homopolymers, and donor–acceptor and donor–acceptor–acceptor copolymers, were synthesized, which feature different contents of acceptor units in polymeric backbones. As imide content increases, the polymer FMO levels were gradually lowered, yielding a transition of charge carrier from ambipolarity to unipolar n-type in organic thin-film transistors (OTFTs). The acceptor–acceptor homopolymer PBTzI possesses the deepest LUMO/HOMO level of −3.94/-6.17 eV, enabling minimal off-current (I off) of 10–10–10–11 A in OTFTs. The highest electron mobility of 1.61 cm2 V–1 s–1 accompanied by small I off of 10–10–10–11 A and high on-current/off-current ratio (I on/I off) of 107–108 was achieved from OTFTs using PDTzTI homopolymer, showing the pronounced advantages of acceptor-acceptor homopolymer approach for developing unipolar n-type polymer semiconductors. The correlations between the FMO levels and the transistor performances underscore the significance of FMO tuning for enabling unipolar electron transport. The results demonstrate that imide-functionalized thiazoles are excellent units for constructing high-performance n-type polymers. Moreover, the synthetic routes to these highly electron-deficient imide-functionalized thiazoles and the polymer structure–property correlations developed here are informative for materials invention in organic electronics.

A distannylated electron‐deficient bithiophene imide (BTI‐Tin) monomer was synthesized and polymerized with imide‐functionalized co‐units to afford homopolymer PBTI and copolymer P(BTI‐BTI2), both featuring an acceptor–acceptor backbone with high molecular weight. Both polymers exhibited excellent unipolar n‐type character in transistors with electron mobility up to 2.60 cm2 V−1 s−1. When applied as acceptor materials in all‐polymer solar cells, PBTI and P(BTI‐BTI2) achieved high power‐conversion efficiency (PCE) of 6.67 % and 8.61 %, respectively. The PCE (6.67 %) of polymer PBTI, synthesized from the distannylated monomer, is much higher than that (0.14 %) of the same polymer PBTI*, synthesized from typical dibrominated monomer. The 8.61 % PCE of copolymer P(BTI‐BTI2) is also higher than those (<1 %) of homopolymers synthesized from dibrominated monomers. The results demonstrate the success of BTI‐Tin for accessing n‐type polymers with greatly improved device performance.

Commercial nanofiltration (NF) membranes have been used to separate dyes and salts in industry; however, NF membrane’s high rejection to divalent salts (i.e., Na2SO4) leads to a reduction of salt recovery. In this study, a tight ultrafiltration (t-UF) ceramic membrane (MWCO 8800 Da) is proposed to fractionate dyes and mixed salts (NaCl/Na2SO4) for textile wastewater treatment. Performance of the t-UF ceramic membrane and DK polymeric membrane (from GE) has been compared regarding to permeability, retention of reactive dyes, and permeation of salts. The t-UF ceramic membrane presents better permeability, competitive rejection of dye molecules (>98%), and reduced rejection of NaCl (<10%) and Na2SO4 (<30%) in comparison with DK membrane; the pure water permeability of t-UF membrane is at least 6 times that of DK membrane. In particular, the operation parameters (TMP, temperature, and pH) and solution environment (concentration and charges) have been intensively evaluated for dye/dual-salts separation efficiency in the membrane process. It also reveals that the t-UF ceramic membrane has performed negative rejection to chloride ions at low operating pressure in the dye and NaCl/Na2SO4 solution due to the electrostatic Donnan effect. Concentration of salt, valence of inorganic ions, and charge of dyes are found as having a significant effect on membrane separation performance. In conclusion, the strong retention of dyes and free permeation of salts (i.e., low retention) by the t-UF ceramic membrane proves that it can be applied to desalinate dyeing wastewater of high salinity and recover dyes and salts separately.

No abstract

The preparation of room-temperature self-healing polymeric materials with good healing efficiency and high mechanical strength is challenging. Two processes are essential to realise the room-temperature self-healing of materials: (a) a...

Starch and montmorrilonite (MMT) were used as raw materials for synthesizing starch-graft-poly-[acrylamide (AM)-acrylic acid (AA)]/MMT superabsorbent nanocomposite by graft and intercalation copolymerization reaction of starch, AM, and AA in the presence of organic MMT micropowder in aqueous solution. Major factors affecting water absorbency such as weight ratio of monomers to starch, weight ratio of AM to AA, neutralization degree of AA, amount of crosslinker, initiator, and MMT were investigated. The superabsorbent nanocomposite synthesized under optimal synthesis conditions exhibits absorption of 1120 g H 2 O/g sample and 128 g H 2 O/g sample in deionized water and in 0.9 wt % NaCl solution, respectively. IR spectra showed that the graft copolymerization between AOH groups on MMT and monomers took place during the reaction, and that crystal interlayer was pulled open in the superabsorbent nanocomposite. X-ray diffraction analysis showed that the crystal interlayer of MMT was pulled open to 2.73 nm, and thus formed nanometer exfoliation composite material. Thermogravimetric analysis showed that starch-graft-poly (AM-AA) superabsorbent nanocomposite (8 wt % MMT) has good thermal stability. This superabsorbent nanocomposite with excellent water absorbency and water retention, being biodegradable in nature, economical and environment friendly, could be especially useful in industry, agricultural, and horticultural applications.

Bis[N,N′‐(alkylamideethyl)ethyl] triethylenediamine surfactants are quaternary ammonium salt Gemini surfactants with amide, which are synthesized from fatty acid (dodecanoic, hexadecanoic, tetradecanoic and octadecanoic) methyl esters, triethylene tetramine and ethyl bromide. The chemical structures of the prepared compounds were characterized by elemental analysis, FTIR and 1H‐NMR spectra, melting point and Krafft point. Several properties of the synthesized surfactants were studied including surface tension, critical micelle concentration, interfacial tension, emulsification power, salt effect, corrosion inhibition efficiency and biological activity. The results show that the surface activity, critical micelle concentration and interfacial activity are correlated to their chemical structures. The emulsification power measurements of these surfactants show their low emulsifying tendency towards Tazhong's crude oil from Tarim Oilfield. The synthesized surfactants also exhibit high biocidal activity towards Gram‐positive and Gram‐negative bacteria and fungi. This activity increases with the increase of alkyl chain length. The corrosion measurement of these surfactants in acidic media with a weight loss technique show good protection of mild steel alloys against acidic environments. These properties suggest that the synthesized compounds have potential for application in the oilfield area.

No abstract