NARROW-DISPERSED CROSSLINKED CORE-SHELL POLYMER MICROSPHERES PREPARED BY SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

Grafting of polystyrene with narrowly dispersed polymer microspheres through surface-initiated atom transferradical polymerization(ATRP)was investigated.Polydivinylbenzene(PDVB)microspheres were prepared by dispersionpolymerization with poly(N-vinyl pyrrolidone)(PVP)as stabilizer.The surfaces of PDVB microspheres werechloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzeneinitiating core sites for subsequent ATRP grafting of styrene using CuCl/bpy as catalytic system.Polystyrene was found to begrafted not only from the particle surfaces but also from within a thin shell layer,resulting in the formation of particles sizeincreased from 2.38-2.58 μm,which can further grow to 2.93 μm during secondary grafting polymerization of styrene.Thisdemonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature.All of the preparedmicrospheres have narrow particle size distribution with coefficient of variation around 10%.

Hydrophilic Modification of Microporous Polysulfone Membrane via Surface-Initiated Atom Transfer Radical Polymerization and Hydrolysis of Poly（glycidylmethacrylate）

Poly（glycidylmethacrylate） （PGMA） brushes were grafted from chloromethylated polysulfone （CMPSF） mem- brane surface by surface-initiated atom transfer radical polymerization （S1-ATRP）, and the grafting was followed by hydrolysis of epoxy groups in the grafting chains to improve the membrane＇s hydrophilie property. Fourier trans- form infrared spectroscopy （FT-IR） and X-ray photoelectron spectroscopy （XPS） measurements confirmed the suc- cessful grafting and hydrolysis of PGMA. The grafting degree of the monomer, measured by periodic acid titration and gravimetric analysis, increased linearly with the polymerization time, while the static water contact angle of the membrane grafted with PGMA or hydrolyzed PGMA linearly decreased. In comparison with the PGMA-grafted membranes, the hydrolyzed PGMA-grafted membranes possess stronger hydrophilicity as indicated by their contact angle and hydration capacity, and as a result they have an improved antifouling property. Therefore, the control of the hydrophilicity of PSF membrane could be realized through adjusting the polymerization time and transforming the functional groups in the grafting chain.

A novel hydrophilic polystyrene-based beads for hydrophilic interaction chromatography by surface-initiated atom transfer radical polymerization

A one-step procedure to hydrophilize monodisperse poly（chloromethyl-styrene-co-divinylbenzene） beads has been presented with 2-hydroxy-3-[4-（hydroxymethyl）-1H-1,2,3-triazol-1-yl]propy1 2-methylacrylate（HTMA） as monomer by surface-initiated atom transfer radical polymerization（SI-ATRP）.The length of the grafted poly（HTMA） chain was varied via controlling the ratio of HTMA to initiator on the surface of the beads.Using these grafted beads as the stationary phase in hydrophilic interaction chromatography,good separation was obtained for nucleosides in the mobile phase of acetonitrile-water.It was also found that the retention time and selectivity of solutes showed a positive relationship with the length of the grafted poly（HTMA） chain.

Grafting β-CD Copolymer Metal Complex from Silicon Gel by SI-ATRP

Polymers grafted from solid surface are being extensively studied with a range of objectives.The most popular living/controlled polymerization used in polymers grafted from solid surfaces is the surface-initiated atom transfer radical polymerization（SI-ATRP）[1,2].An attractive feature of atom transfer radical polymerization（ATRP） is to simultaneously grow chains from multifunctional surface.Thus the grafted polymer with well-defined structures could be designed and controlled.ATRP has proven to be a powerful tool to synthesize homopolymers and copolymers,under easily accessible experimental conditions[3-7].Furthermore it is useful for the functionalization of material surfaces by grafting certain polymers.

Preparation of poly (N-isopropylacrylamide) brush bonded on silicon substrate and its water-based lubricating property

The poly (N-isopropylacrylamide) brush was covalently bonded on an initiator-coated silicon wafer via surface-initiated atom transfer radical polymerization. The polymer brush was (76.2±0.1) nm in thickness (by ellipsometer) with a grafting density of ca. 0.27 chains/nm 2 . The tribological properties of the poly (N-isopropylacrylamide) brush were investigated by means of ball-on-disk tests in a rotational mode under water lubrication for tribological application. The experimental results exhibited a low friction coefficient of ca. 0.03. The excellent lubrication property of the brush was due to its amide groups in the polymer chains. It was supposed that the good lubrication property of the brush was attributed to the cross-linked polymer network formed by the hydrogen bond association of N-H…O==C and the water molecular layer adsorbed by the terminal amide groups in the brush. The poly (N-isopropylacrylamide) solution also exhibits a lubrication property due to physical adsorption of the polymer chains.

Preparation and Biocompatibility of Polyester Films Grafted with Functional mPEG Copolymers

The surface ofpoly（ethylene terephthalate）（PET） films is inert, hydrophobic, and incompatible with blood, which has limited its practical bioapplication. In this case, better biocompatibility could be achieved by surface modification. In this study, the grafted copolymer of functional methoxypolyethylene glycol（mPEG） derivatives and styrene from the PET surfaces was prepared via surface-initiated atom transfer radical polymerization（SI-ATRP）. The structures, composition, properties and surface morphology of the grafted PET films were characterized by Fourier transform infrared spectroscopy（FTIR）, X-ray photoelectron spectroscopy（XPS）, contact angle measurements and scanning electronic microscopy（SEM）. The results indicate that the surface of the PET films has been covered by a thick targeted copolymer layer that converted the hydrophobic surface of PET to an amphiphilic surface. The bacte- rial adhesion and cell culture results indicate the copolymer-grafted PET film may possess good biocompatibility.