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A 20 MHz quartz crystal microbalance (QCM) sensor coated with in situ self-assembled molecularly imprinted polymers (MIPs) was presented for the detection of trace microcystin-LR (MC-LR) in drinking water. The sensor performance obtained using the in situ self-assembled MIPs was compared with traditionally synthesized MIPs on 20 MHz and normal 10 MHz QCM chip. The results show that the response increases by more than 60% when using the in situ self-assembly method compared using the traditionally method while the 20 MHz QCM chip provides four-fold higher response than the 10 MHz one. Therefore, the in situ self-assembled MIPs coated on a high frequency QCM chip was used in the sensor performance test to detect MC-LR in tap water. It showed a limit of detection (LOD) of 0.04 nM which is lower than the safety guideline level (1 nM MC-LR) of drinking water in China. The low sensor response to other analogs indicated the high specificity of the sensor to MC-LR. The sensor showed high stability and low signal variation less than 2.58% after regeneration. The lake water sample analysis shows the sensor is possible for practical use. The combination of the higher frequency QCM with the in situ self-assembled MIPs provides a good candidate for the detection of other small molecules., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Thermo-responsive magnetic molecularly imprinted polymers (TMMIPs) for selective recognition of curcuminoids with high capacity and selectivity have firstly been developed. The resulting TMMIPs were characterized by TEM, FT-IR, TGA, VSM and UV, which indicated that TMMIPs showed thermo-responsiveness [lower critical solution temperature (LCST) at 33.71°C] and rapid magnetic separation (5s). The polymerization, adsorption and release conditions were optimized in detail to obtain the highest binding capacity, selectivity and release ratio. We found that the adopted thermo-responsive monomer [N-isopropylacrylamide (NIPAm)] could be considered not only as inert polymer backbone for thermo-responsiveness but also as functional co-monomers combination with basic monomer (4-VP) for more specific binding sites when ethanol was added in binding solution. The maximum adsorption capacity with highest selectivity of curcumin was 440.3μg/g (1.93 times that on MMIPs with no thermosensitivity) at 45°C (above LCST) in 20% (v/v) ethanol solution on shrunk TMMIPs, and the maximum release proportion was about 98% at 20°C (below LCST) in methanol-acetic acid (9/1, v/v) solution on swelled TMMIPs. The adsorption process between curcumin and TMMIPs followed Langumuir adsorption isotherm and pseudo-first-order reaction kinetics. The prepared TMMIPs also showed high reproducibility (RSD<6% for batch-to-batch evaluation) and stability (only 7% decrease after five cycles). Subsequently, the TMMIPs were successfully applied for selective extraction of curcuminoids from complex natural product, Curcuma longa., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Due to their high electronegativity and small atomic radius without undesirable steric hindrance, the incorporation of fluorine atoms onto a conjugated backbone has been proven to be a very effective way to tune the energy levels of organic semiconductors. In this paper, 5-fluorobenzo[c][1,2,5]thiadizole was adopted as the electron-deficient unit, thiophene and alkylthiophene as donor units, and further, thiophene and EDOT were taken as peripheral donor units, and one D–A–D and two D–π–A–π′–D fluorinated electrochromic polymer precursors were successfully synthesized via a Stille coupling reaction, namely F-BT, F-BT-Th, and F-BT-EDOT. Due to the elongation of the π-conjugated systems of precursors with the stronger electron-donating ability of the EDOT unit, the oxidation potential of the F-BT-EDOT precursor was further reduced to 0.56 V vs. Ag/AgCl accompanied by red-shifted electronic spectra. As-electropolymerized P(F-BT-EDOT) also showed favorable redox activity and excellent redox stability (<2.33% electroactivity loss after 1000 cycles). At the same time, the optical band gap of P(F-BT-EDOT) (1.37 eV) is much lower than that of P(F-BT-Th) and P(F-BT) (1.62 eV), and a stable reversible electrochromic change from dark green to dark blue was achieved with a fast response time. In the near-infrared region, P(F-BT-EDOT) shows intriguing overall electrochromic performance with a high optical contrast of up to 33% and a coloration efficiency of 196.3 cm2 C−1 at 1100 nm. It can be seen that the introduction of a strong electron-donor EDOT unit could bring about a new breakthrough in the electrochromic performance of 5-fluorobenzo[c][1,2,5]thiadizole-based fluorinated D–A polymers and enhancement in their stability, and it is expected to be applied in near-infrared electrochromic devices. [ABSTRACT FROM AUTHOR]

Chlorinated organic materials have drawn much attention and have been applied in various fields due to their intriguing properties such as easy accessibility with low cost, high capability to hold electron density, and “heavy-atom effect”. In this work, a kind of highly fluorescent chlorinated semiconducting polymer dot (PFDPClBT) is developed for cell imaging by using an amphiphilic polymer poly(styrene-co-maleic anhydride) as the co-encapsulation matrix. The PFDPClBT dots show a small particle size of about 50 nm, a large Stokes shift of 125 nm, quite high fluorescence quantum yields (QYs) of 20.3% (PFDPBT: 8.5%), and increased reactive oxygen species generation efficiency. Since the chlorinated Pdots are brighter than their non-chlorinated counterparts and can label the target cell effectively with low cytotoxicity, they are promising fluorescent probes in bioimaging applications. [ABSTRACT FROM AUTHOR]

Injection molding is the most widely used process in manufacturing polymer products. The warpage induced during injection molding process has an important influence on the mechanical performance of injection molded products. Therefore, how to optimize process parameters becomes the key issue in improving the mechanical performance of the product towards the expected service conditions. In this paper, a combined artificial neural network and particle swarm optimization (PSO) algorithm method is proposed to optimize the injection molding process. An integrated finite element analysis of the injection molding process, the warpage-induced residual stresses during assembly, and mechanical performance of serviced product is firstly proposed. A back propagation neural network model is then developed to map the complex nonlinear relationship between process parameters and mechanical performance of the product. The PSO algorithm is interfaced with this predictive model to optimize process parameters and thereby significantly improve the mechanical performance. A case study of vehicle window made of polycarbonate (PC) is presented. Optimum values of process parameters are determined to minimize the maximum von Mises stress within the PC vehicle window under impact loading. [ABSTRACT FROM AUTHOR]

Chlorination has proved to be an efficient method in tuning energy levels and optoelectronic properties of organic semiconducting materials with cheaper synthesis and low-cost raw materials when compared with the fluorinated analogues. Herein, in this work, 5-chlorobenzo[c][1,2,5]thiadizole (Cl-BT) unit was chosen as a new acceptor unit to design two new D-A type electrochromic conjugated polymer: P(Cl-T) and P(Cl-EDOT). The electrochemical behavior and electrochromic performances of above-mentioned chlorinated polymers were studied by electrochemical polymerization techniques and spectroelectrochemistry. Thanks to the strong electron-withdrawing ability of Cl-BT unit and the strong electron-donating properties of EDOT unit, the resultant Cl-EDOT precursor could electropolymerize into high quality hybrid polymer films at lower potential (0.71 V vs. Ag/AgCl) with favorable redox activity and better redox stability. Spectroelectrochemistry shown that as-formed lower band gaps P(Cl-EDOT) exhibits reversible color-changing nature from pale blue to gray accompanied with the moderate optical contrast (13.9%), fast response time (0.6 s), and favorable coloration efficiency (126.4 cm2 C−1) in the NIR region that was measured from the kinetic studies. By optimizing the tested electrolyte and solution, its electrochromic performance is further improved (optical contrast: 25.6%, response time: 0.25 s, coloration efficiency: 275.9 C−1 cm2). The favorable redox stability and electrochromic performance of P(Cl-EDOT) make it a good candidate to construct electrochromic device, and Cl-BT unit should be a promising building block in designing high performance near infrared electrochromic materials. [Display omitted] • Two electrochromic precursor based on 5-chlorobenzo[c][1,2,5]thiadizole unit were synthesized by Stille coupling reaction. • Different donor brings different influence on the photophysical properties of the chlorinated precursors and its polymers. • The introduction of EDOT unit is beneficial for the preparation of better-quality chlorinated polymers. • P(Cl-EDOT) exhibit better redox activity and stability, and satisfied electrochromic performances. • Chlorinated benzothiadiazole could be a promising building blocks in constructing high performance D-A conjugated polymers. [ABSTRACT FROM AUTHOR]

• Two new D-π-A-π-D type monomers based on mono-chlorinated benzothiadiazole acceptor unit were synthesized. • Types of donor units caused significant effects on the photophysical properties of the chlorinated monomers and its polymers. • Lower oxidation potential of Cl-EDOT was beneficial for the chlorinated polymer's optoelectronic properties. • Lower band gaps P(Cl-EDOT) revealed favorable redox activity and stability, reversible electrochromic nature, and outstanding electrochromic performances. • Chlorinated benzothiadiazole could be a promising building block in designing high-performance D-A electrochromic polymers. Chlorinated benzothiadiazole (Cl-BT) unit, as a new type of electron-accepting building block with the advantages of easy large-scale synthesis in high yields, has been found to be very promising in designing high performance electroactive polymers with decent optoelectronic properties. Most recently, the Cl-BT unit-based D-A polymers have been applied in many organic electronic devices, but little attention was paid to their electrochromic applications. Herein, in this work, to further evaluate the electrochromic performances of the Cl-BT unit-based chlorinated D-A polymers, two new D-π-A-π-D type chlorinated monomers (Cl-Th and Cl-EDOT) which using mono-chlorinated benzothiadiazole unit as the acceptor unit and thiophene/3,4-ethylenedioxythiophene (EDOT) as the donor unit, was successfully synthesized by Stille coupling reaction and then yield their corresponding chlorinated polymer films (P(Cl-Th) and P(Cl-EDOT)) by electrochemical deposition method. Due to the stronger electron donor ability of EDOT unit, the monomer Cl-EDOT has red-shifted UV–Vis and emission spectra and more significant Stoke's shifts. The lower oxidation potential of Cl-EDOT was very beneficial for improving its resultant D-A chlorinated polymer's optoelectronic properties. As a result, as-formed lower band gap P(Cl-EDOT) (∼1.31 eV) showed reversible color change from the neutral dark green to the oxidized dark blue accompanied with outstanding electrochromic properties, including high optical contrast (24.3%), speedy response time (0.6 s), and high coloration efficiency (170.8 cm2/C), as well as favorable redox stability (70% activity retention after 1000 cycles). The favorable electrochromic performances and good optical stability of P(Cl-EDOT) make it a promising candidate in electrochromic devices. Overall, the chlorinated benzothiadiazole and its derivatives were promising building blocks in constructing high-performance D-A electrochromic polymers. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Polydimethylsiloxane (PDMS)/organic montmorillonite (OMMT)/polyether polyethersulfone (PES) composite membranes were prepared by in situ anionic polymerization using 3-aminopropyltrimethoxy (AMEO) as a crosslinker. The morphology, thermal properties and interaction of PDMSAMEO/OMMT membranes were characterized by using a scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and a thermal gravimetric analysis (TGA). The swelling behavior of membranes without PES support was investigated. The effects of AMEO content and OMMT content on separation properties were also studied. The results show that the addition of appropriate OMMT could improve the hydrophobic and pro-acetic acid properties of a membrane. The acetic acid selectivity of membranes was best when AMEO content was 0.1. The membrane, loading 2wt.% OMMT, exhibited the highest separation factor for a feed concentration of 10wt.% at 313K. An increase in feed concentration resulted in the enhancement of flux and selectivity. When the feed concentration was above 20wt.%, the separation factor of a filled membrane was larger than for an unfilled membrane. With increases in the feed temperature, the permeation flux of membranes increased. However, the acetic acid selectivity of an unfilled membrane decreased but for filled membranes initially increased before decreasing. [Copyright &y& Elsevier]