Preparation and Characterization of the Modified Polyvinylidene Fluoride (PVDF) Hollow Fibre Microfiltration Membrane

A novel thermally induced graft polymerization technique was used to modify a polyvinylidene fluoride （PVDF） hollow fibre microfiltration membrane. An artificial neural network （ANN） was applied to optimize the prepared condition of the membrane. The optimized dosing of acrylic acid （AA）, acrylamide （AM）, N, N＇- methylenebisacrylamide （NMBA） and potassium persulphate （KSP） designed by ANN was that AA was 40.63 ml/L; AM acted as 6.25 g/L; NMBA was 1.72 g/L and KSP was 1.5 g/L, respectively. The thermal stability of the PVDF modified hollow fibre membrane （PVDF-PAA） was investigated by thermogravimetric （TG） and differential scanning calorimetry （DSC） analysis. The polycrystallinity of the PVDF-PAA membrane was evaluated by X-ray diffraction （XRD） analysis. The complex formation of the modified membrane was ascertained by Fourier transform infrared spectroscopy （FTIR）. The morphology of the PVDF-PAA membrane was studied by environmental scanning electron microscopy （ESEM）. The surface compositions of the membrane were analyzed by X-ray photoelectron spectroscopy （XPS）. The adsorption capacity of Cu^2＋ ion on the PVDF-PAA hollow fibre membrane was also investigated.

Effects of Cu^2＋ Counter Ions on the Actuation Performance of Flexible Ionic Polymer Metal Composite Actuators

The resistance of Ionic Polymer Metal Composite （IPMC） electrodes plays an important role in the actuation performance of IPMC actuators. Owing to crack formation on the surface of platinum electrode, the surface resistance of the electrode increases, which greatly limits its actuating performance. In this paper, we proposed a new method of dynamic self-repair electrodes by ex- changing Cu2＋ into the IPMC basement membrane. IPMC actuators with Cu2＋ were prepared and the actuation performance in the air was subsequently measured. Compared with conventional IPMC actuators containing Li＋ counter ions, those containing Cu2＋ counter ions exhibited 2 times - 3 times larger displacement and 2 times -3 times bigger blocking force. In the morphology observation, we found that many small copper particles scattered in the middle of cracks after several bending cycles, which leads to an obvious decrease in electrode resistance. In the Cyclic Voltammetry （CV） scan measurement, we observed that the oxidation reaction of copper alternates with reduction reaction of copper ions with the change of voltage polarity, which was a dynamic process. Based on these analyses, it is concluded that the presence of Cu2＋ can repair the damaged electrodes and induce lower electrode resistance, thus leading to the performance improvement of actuation.

Electrochemiluminescence of 1,8-Naphthalimide-Modified Carbon Nitride for Cu^(2+) Detection

It is essential to screen novel luminophores and co-reactants for the development of electrochemiluminescence(ECL)systems.In this work,a series of 1,8-naphthalimide-modified graphitic carbon nitride(CN/1,8-NDI_(x))ECL luminophores were successfully developed for the quantitative determination of Cu^(2+)with K_(2)S_(2)O_(8)as a co-reactant.When CN/1,8-NDI_(x)was immobilized on the surface of the glassy carbon electrode(GCE),a strong ECL signal could be produced(at a potential of-1.3 V vs.Ag/AgCl),which was threefold stronger than that of unmodified g-C_(3)N_(4).The intensity of ECL could be linearly quenched by Cu^(2+)over a concentration range from 5×10^(-9)to 1×10^(-4)mol/L,and with a low limit of detection(LOD)of0.86 nmol/L.Our results may provide a new perspective on the novel ECL platforms development.