Jiangyu Wu

Preparation of polyaniline-metal composite nanospheres by in situ microemulsion polymerization

Nanosized metal and polyaniline (PANi) composite spheres have been prepared via the polymerization of aniline using PdCl(2) or HAuCl(4) as the oxidant in a microemulsion system. The oxidization of aniline and the reduction of metal ion happened together during the reaction, yielding PANi and elemental metal simultaneously. The results of FTIR spectra suggested that the oxidation degree of PANi was affected by the initial ratio of metal ions to monomer in the microemulsion system. The PANi-metal nanospheres were characterized using X-ray photoelectron spectroscopy and the conductivity of the composite nanospheres was measured by conventional four-probe method. Scanning and transmission electron microscopy were used to show the morphology of the composites.

Surface-initiated Atom-transfer Radical Polymerization from Polyimide Films and Their Anti-fouling Properties

A simple one-step method for the chloromethylation of polyimide (PI) under mild conditions was used to introduce benzyl chloride groups into PI film surface. Covalently tethered hydrophilic polymer brushes of poly(ethylene glycol) monomethacrylate (PEGMA) and glycidyl methacrylate (GMA) were prepared via surface initiated atom-transfer radical polymerization (ATRP) from the chloromethylated PI surfaces using benzyl chloride groups as the active ATRP initiators. A kinetics study indicated that the chain growth from the films was in agreement with a controlled process. The dormant chain ends of the grafted polymer on the PI films could reinitiate the consecutive surface-initiated ATRP to prepare surface-functionalized diblock copolymer brushes on the PI films. The modified surface was characterized by X-ray photoelectron spectroscopy (XPS) after each modification stage. Protein adsorption experiments indicated that the PI-P(PEGMA) membrane exhibited substantially improved anti-fouling properties compared to the pristine PI surface.

Surface-initiated atom-transfer radical polymerization from polyethersulfone membranes and their use in antifouling

Abstract A simple one-step method for the chloromethylation of polyethersulfone (PES) under mild conditions provided surface benzyl chloride groups as the active initiators for the surface-initiated atom-transfer radical polymerization (ATRP) to tailor the functionality of the PES membrane. Functional hydrophilic polymer brushes of poly(ethylene glycol)monomethacrylate (PEGMA) and sodium 4- styrenesulfonate (NaStS), as well as their block copolymer brushes, were prepared via surface initiated ATRP from the chloromethylated PES surfaces. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to characterize the surface-modified membranes. The PEGMA-grafted PES membranes showed great protein resistance to protein adsorption compared to the pristine PES surface.

Functionalization of Poly(ether imide) Membranes via Surface-Initiated Atom-Transfer Radical Polymerization and their Use in Antifouling

Poly(ether imide) (PEI) was chloromethylated by a simple one-step method under mild conditions to provide surface benzyl chloride groups as the active initiators for the surface-initiated atom-transfer radical polymerization (ATRP). Functional hydrophilic polymer brushes of poly(ethylene glycol) monomethacrylate and sodium 4-styrenesulfonate, as well as their block copolymer brushes, were synthesized via surface-initiated ATRP from the chloromethylated PEI membrane surfaces. The surface-modified membranes were studied by X-ray photoelectron spectroscopy. Using the bovine serum albumin solution adsorption test, the grafted PEI membranes showed great antifouling properties compared to the pristine PEI surface. Thus, the chloromethylated PEI membranes with the active ATRP initiators opens up opportunities for the functionalization of membranes via surface molecular design.

Dextran gadolinium complex containing folate groups as a potential magnetic resonance imaging contrast agent

Folate-containing dextran ligand (FA-Dextran-DTPA) was synthesized by the incorporation of diethylenetriaminepentaacetic acid (DTPA) and folate (FA) as a tumor-targeting group into dextran as a polymer carrier. This ligand was further reacted with gadolinium chloride to make a dextran gadolinium complex FA-Dextran-DTPA-Gd. The ligand and its gadolinium complex were characterized by 1H-NMR, FTIR, UV-Vis, average particle sizes and zeta potential, as well. In vitro properties including relaxivity, cytotoxicity assay, cellular uptake assay, and magnetic resonance imaging (MRI) were also evaluated. Compared with Gd-DTPA, FA-Dextran-DTPA-Gd possessed obviously higher relaxation effectiveness and lower cytotoxicity to HeLa cells. FA-Dextran-DTPA-Gd had a high affinity to the H460 and MDA-MB-231 tumor cells and can be taken up selectively by these tumor cells. Moreover, FA-Dextran-DTPA-Gd showed enhanced signal intensities (SI) of MRI and enhanced the contrast of MR images of tumor cells. These results indicated that FA-Dextran-DTPA-Gd showed the potential as a tumor-targeting contrast agent in MRI.