Guoyong Xu

Synthesis and characterization of water-soluble multiwalled carbon nanotubes grafted by a thermoresponsive polymer

Water-soluble multiwalled carbon nanotubes (MWNTs) with temperature-responsive shells were successfully prepared by grafting poly (N-isopropylacrylamide) (PNIPAM) from the sidewalls of MWNTs, via surface reversible addition-fragmentation chain transfer (RAFT) polymerization using RAFT agent functionalized MWNTs as the chain transfer agent. Thermogravimetric analysis (TGA) measurements showed that the weight composition of the as-grown PNIPAM polymers on the MWNTs can be well controlled by the feed ratio (in weight) of NIPAM to RAFT agent functionalized MWNTs (MWNT-SC(S)Ph). The MWNT-g-PNIPAM has good solubility in water, chloroform, and tetrahydrofuran (THF). Transmission electron microscope (TEM) and scanning electron microscope (SEM) images also showed that the MWNT-g-PNIPAM was dispersed individually and eventually bonded with the polymer layer by surface RAFT polymerization. The PNIPAM shell is very sensitive to a change of temperature. This method could find potential applications by grafting other functional polymer chains onto MWNTs.

Fabrication of silver/cross-linked poly(vinyl alcohol) cable-like nanostructures under γ-ray irradiation

Ag/cross-linked poly(vinyl alcohol) (PVA) cable-like nanostructures were synthesized with control in an aqueous solution of a hydrolysable amphiphilic block polymer, poly(vinyl acetone) (PVKA) (ketalization degree DH = 0.533) under γ-ray irradiation, via one-step in situ reduction of Ag+ and cross-linking of alcohol units. In the present approach, we try to control the speed of the cross-linking reaction of PVA chains (alcohol units), which are yielded from the hydrolysed PVKA, utilizing the low hydrolysis rate of the PVKA in dilute acidic solution.

Functionalized carbon nanotubes with polystyrene-block-poly (N -isopropylacrylamide) by in situ RAFT polymerization

A fascinating nano-object, amphiphilic polymer brushes with a hard core of multiwalled carbon nanotubes (MWNTs) and a relatively soft shell of polystyrene-block-poly (N-isopropylacrylamide) (PS-b-PNIPAM), was easily constructed by in situ surface reversible addition–fragmentation chain transfer (RAFT) polymerization of styrene followed by N-isopropylacrylamide on the modified convex surfaces of MWNTs (MWNT-PS). The structure and morphology of the as-prepared hybrid nanomaterials were characterized and confirmed by Fourier-transform infrared (FTIR) spectrometry, nuclear magnetic resonance (NMR) spectrometry, thermogravimetric analysis (TGA) and Raman spectroscopic analysis. The MWNT-PS-b-PNIPAM that was produced has a PNIPAM block, which is very sensitive to temperature. Such a complex nano-object could open a door to the fabrication of novel functional carbon nanotube-based nanomaterials or nanodevices with designable structures and tailor-made properties.

In situ formation of Ag flowerlike and dendritic nanostructures in aqueous solution and hydrolysis of an amphiphilic block copolymer

Silver flowerlike and dendritic nanostructures were synthesized in an aqueous solution of a hydrolysable amphiphilic block copolymer polyvinylacetone (PVKA) via in situ reduction of Ag(+) and hydrolysis of PVKA at room temperature. Compared with a previous result, the complete hydrolysis time of PVKA is greatly shortened in this process.

Controlled synthesis of novel 3D dendritic Bi2S3 /cross-linked poly(vinyl alcohol) nanocomposites

Novel spherical three-dimensional (3D) dendritic Bi2S3 /cross-linked poly(vinyl alcohol) (PVA) nanocomposites were successfully synthesized in aqueous solution of amphiphilic polyvinylacetone (PVKA) (ketalization degree DH = 0.549), via one-step in situ decomposition of the complex [Bi(Tu)x]3+ under γ-ray irradiation, utilizing the controllable hydrolysis property of PVKA in acidic solution. Herein, PVA chains are obtained from the hydrolysed PVKA. These uniform 3D spherical nanocomposites have a structure similar to that found in the natural lotus leaf, where every microscale papilla on the leaf surface is covered by nanoscale papillae.

Novel dendritic nanostructures: self-assemblies of nanoparticles of poly(vinyl alcohol) coated Ag and/or Cu2O

Novel dendritic nanostructures, which are actually self-assemblies of nanoparticles of poly(vinyl alcohol) (PVA) coated Ag and/or Cu2O, were controllably synthesized in an aqueous solution of amphiphilic polyvinylacetone (PVKA) (DH = 0.549), via a one-step in situ reduction of Ag+ and Cu2+ under γ-ray irradiation, using the low hydrolysis rate of the PVKA in the dilute acidic solution. Subsequently, the hydrolysis of PVKA yields PVA chains.