Abstract.A new conjugated polymer with donor-accepter architectures poly[1,4-dioctyloxyphenylene-2,5-diylethenylene-(2,3-dipyridine-2-ylquinoxaline-5,8-diyl)ethylene] (PPV-BD) was synthesized successfully, in which the electron-donating unit was alkoxy substituted phenyl ring, and the electron-accepting unit was a quinoxaline. The resulting polymer had a lower band-gap (1.98 eV) compared to poly[2-methoxy-5-(2-ethyl)hexoxy-phenylenevinylene] (MEH-PPV, 2.12 eV), and was characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), ultraviolet-visible (UV-vis) spectroscopy, photoluminescence (PL) spectroscopy and X-ray diffraction (XRD). Its photoinduced charge transfer applications in polymer solar cell (PSC) and trinitrotoluene (TNT) detection were studied respectively, and the results indicated that this polymer might be a good candidate material for PSC or detecting TNT in solution.

The solid-state polymerization of diacetylenes (MDA-PBT-PDA) is studied with a concerted reaction model and the calculation method of EHMO-ASED and EHCO-ASED, where MDA = crystalline molecular diacetylenes, PBT = polybutatrienes, and PDA = polydiacetylenes. As the reaction goes on, the symmetry of frontier orbitals inverts at state PBT, HOCO from C,-antisymmetry to C2-symmetry and LUCO from C2-symmetry to C,-antisymmetry, which means completion of the 1,4-addition. Two necessary conditions must be satisfied for the reaction to take place: 1) the geometric parameters must undergo a series of concerted changes to make the conformation suitable for the intermolecular 1 ,Caddition, which should overcome an energy barrier Eb; 2) the symmetry match between the frontier crystal orbitals of the reactant and the product must be satisfied-electrons of the reactant should be excited from HOCO (C,-antisymmetry) into LUCO (C2-symmetry), which faces an energy gap E,. At state MDA, there is E,(MDA) = 5.6 eV. If MDA and PDA are analyzed according to Woodward-Hoffmann's rules, this reaction would be considered photochemically allowed but thermochemically forbidden. It has been shown that the Eg gradually decreases along the reaction coordinate from state MDA to PBT. At state PBT there is E,(PBT) I 0.1 eV, and the electrons of the reactant can be easily excited 471

To enhance the anti-fouling and separating properties of polyvinylidene fluoride (PVDF) membranes, an amphiphilic copolymer of methyl methacrylate and 2-acrylamido-2-methylpropane sulfonic acid, poly(MMA-co-AMPS), was designed and synthesized. Through a phase-inversion process, the poly(MMA-co-AMPS) were fully dispersed in the PVDF membrane. The properties of membrane including the surface and cross-section morphology, surface wettability and fouling resistance under different pH solutions were investigated. Compared to the unmodified PVDF membranes, the contact angles of modified PVDF membranes decreased from 80.6° to 71.6°, and the pure water flux increased from 54 to 71 L·m−2·h−1. In addition, the hybrid PVDF membrane containing 0.5 wt% copolymers demonstrated an larger permeability, better fouling resistance and higher recovery ratio via pure water backlashing, when it was compared with the other blend membranes, and the virgin one in the cyclic test of anti-fouling. The modified membranes with the copolymers possessed an outstanding performance and may be used for further water treatment applications.

We use Brownian dynamics simulations to study the adsorption behavior of a nanosized particle on polymer brushes. The adsorption process, the dynamic behavior of the nanoparticle in brush, the penetration depth, and the diusion coecient of the nanoparticle in dierent depths of the brush are all investigated for dierent grafting densities. We provide an area density Γ , which is the area average of the monomer number above the embedded nanoparticle in brush. We nd that this area density explains well qualitatively the experimental phenomenon that the nanoparticles exhibit a maximum in the adsorbed amount as a function of the grafting density of brush.