Xuan Thang Cao

Characterization of poly(diphenylamine)-gold nanocomposites obtained by self-assembly

Composites of poly (diphenylamine) and gold nanoparticles were chemically prepared from solutions which containing methane sulfonic acid (MSA) with the addition of gold chloride trihydrate as the oxidant as a source for initiation of polymerization and a generation of Au nanoparticles. Poly (diphenylamine) decorated with noble-metal gold nanoparticles were synthesized successfully and exposure of the solutions to caused polymerization of diphenylamine to polymerize with gold salt. The nanocomposites were characterized for the structure, morphology and electronic properties through X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM) and UV-visible spectroscopy.

Preparation and Characterization of Poly(4-vinylpyridine) Encapsulated Zinc Oxide by Surface-Initiated RAFT Polymerization

Poly(4-vinylpyridine) was covalently wrapped onto ZnO nanoparticles through surface initiated Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization upon grafting from protocol. The surface of ZnO nanoparticles was initially modified by the coupling reaction with silane leading to trithiocarbonate functionalized ZnO nanoparticles (ZnO-RAFT). The controlled radical polymerization of 4-vinylpyridine in the presence of the ZnO-RAFT afforded PVP-g-ZnO nanocomposites. FT-IR, EDX, XRD and XPS analyses demonstrated the grafting of PVP on the surface of ZnO nanoparticles, while thermal stability of PVP-g-ZnO nanocomposites was confirmed by TGA analysis. The TEM and SEM images suggested that ZnO nanoparticles were embedded in the polymer, and the dispersibility of the nanocomposites was improved in an organic solvent dramatically.

Preparation, characterization and application of magnetic halloysite nanotubes for dye removal

ABSTRACT Magnetic functionalized halloysite nanotubes (MNPs/HNTs) was prepared and their effective adsorption for methylene blue (MB) was illustrated. Initially, poly(glycidyl methacrylate) grafted magnetic nanoparticles (MNPs-g-PGMA) were prepared by the reversible addition fragmentation chain transfer (RAFT) polymerization of glycidyl methacrylate. The fabrication of MNPs-g-PGMA and amino-modified halloysite nanotubes (HNTs-NH2) was carried out by the reaction of epoxy rings and amino functional groups to afford MNPs/HNTs. The composite was characterized by using FT-IR, XRD, TGA, SEM, and TEM analyses. The adsorption performance of MNPs/HNTs was evaluated by the adsorption experiment of MB in aqueous solution.

Synthesis of Poly(ϵ-caprolactone) Grafted Poly(2-hydroxyethyl methacrylate) Functionalized Hydroxyapatite by RAFT and ROP

Poly(ϵ-caprolactone) grafted poly(2-hydroxyethyl methacrylate) functionalized hydroxyapatite (HAP@PHEMA-g-PCL) nanocomposites were synthesized by the combination of reversible addition fragmentation chain transfer (RAFT) polymerization and ring-opening polymerization (ROP). The RAFT agent was anchored on the surface of hydroxyapatite nanocrystals (HAPs) through the silane condensation process of 3-chloropropyltrimethoxysilane followed by reaction with potassium xanthogenate. Poly(2-hydroxyethyl methacrylate) (PHEMA) was covalently functionalized on the surface of HAPs by RAFT polymerization. Then, poly(ϵ-caprolactone) (PCL) was grafted on HAPs by ROP based on the hydroxyl groups of PHEMA to afford HAP@PHEMA-g-PCL. The structure and composition of HAP@PHEMA-g-PCL nanocomposites were characterized by FT-IR, XRD, and TGA analyses. The morphology and formation of the polymer encapsulating HAPs were demonstrated from SEM and TEM images, while the 1H MNR analysis of the cleaved PHEMA-g-PCL confirmed the grafting.

A Simple Synthesis, Characterization, and Properties of Poly(methyl methacrylate) Grafted CdTe Nanocrystals

A facile chemical synthesis of poly(methyl methacrylate) (PMMA) grafted CdTe nanocrystals (CdTe NCs) has been realized. Initially, CdTe NCs were prepared in a controlled manner using 2-mercaptoehanol (ME) as a capping agent. Then, 3-(trimethoxysilyl) propyl methacrylate having C˭C double bonds were anchored with ME capped CdTe NCs through condensation reaction. Subsequently, AIBN initiated in situ free radical polymerization provided PMMA-g-CdTe nanohybrids. The FT-IR investigation suggested the formation of robust covalent bonding between CdTe NCs and the organic PMMA segment. XPS analysis also confirmed PMMA-g-CdTe nanohybrids. The physical structure and morphology of the as-prepared nanohybrids were studied by XRD and TEM. The thermal stability of the hybrids was enhanced in comparison with pure PMMA as indicated by TGA analysis. The UV-Vis absorption and photoluminescence measurements of the PMMA-g-CdTe nanohybrids showed their potential optical properties.

Fabrication and adsorption properties of novel magnetic graphene oxide composites for removal of methylene blue

ABSTRACT The hybrid material of magnetic graphene oxide (MNPs/GO) was prepared with a facile route and adsorption properties for removal of methylene blue (MB) were investigated. Initially, the surface of magnetic nanoparticles (MNPs) was modified with poly(glycidyl methacrylate) by the surface-initiated reversible addition fragmentation chain transfer (RAFT) polymerization. The modified MNPs and graphene oxide (GO) were fabricated to form MNPs/GO in N,N-dimethylformamide at 60°C. The composites were characterized by using XRD, SEM, TEM, and vibrating sample magnetometry analyses. The adsorptive removal of MB on the adsorbent obeyed a pseudo-second-order kinetic whose equilibrium data were fitted well to the Langmuir isotherm model and the maximum MB uptake of MNPs/GO was estimated from this model to be 153.85 mg/g. MNPs/GO adsorbent could be recycled and maintained 75.3% of its initial adsorption capacity for MB after five regeneration cycles.

Preparation and characterization of poly(oligo(ethylene glycol) methacrylate)-grafted-layered double hydroxides by RAFT polymerization

ABSTRACT The composite material based on poly(oligo(ethylene glycol) methacrylate)-grafted-layered double hydroxides/Gentamicin (LDHs-g-POEGMA-GE) was prepared by the reversible addition fragmentation chain transfer polymerization, and its antibacterial property was investigated. Initially, the surface of LDHs was modified by S′-(3-trimethoxysilyl) propyl trithiocarbonate as a chain transfer agent and then grafted with POEGMA. Subsequently, GE was covalently linked to the POEGMA chains by esterification reaction producing LDHs-g-POEGMA-GE. The composites were characterized by using FT-IR, GPC, XRD, TGA, and SEM analyses. The in-vitro assay with Staphylococcus aureus bacteria indicated the high antibacterial activity of the composites, which promises potential applications in the biomaterial field.

A Facile Route Towards the Synthesis of Nanocomposites for the Application as Solid Electrolytes via Grafting Polymer from TiO2 Nanoparticles

Poly(acrylic acid)/TiO2 (PAA-g-TiO2) nanocomposites were synthesized by the surface thiol-lactam initiated radical polymerization (TLIRP) technique. The synthetic strategy involved the modification of TiO2by a one-step direct anchoring of thiol groups via reaction between the hydroxyl groups on the surface of TiO2 and triethoxysilane groups of (3-mercapto)propyltrimethoxysilane (MPTMS). The modified TiO2nanoparticles (NPs) were dispersed in acrylic acid monomers and subsequently polymerized by TLIRP to yield PAA-g-TiO2nanocomposites. FT-IR spectra, XPS, EDS, UV-Vis spectroscopy and SEM images provided direct and clear evidence for the coordination of MPTMS and the presence of PAA on TiO2 NPs. The immobilization of PAA onto TiO2 NPs significantly improved their dispersibility in organic solvents. Additionally, laser diffraction spectroscopy of the TiO2 NPs was examined in order to get the size distribution of nanocomposites.

A Facile Esterification Reaction Towards the Synthesis of Poly(methyl methacrylate)/Titanium Dioxide Nanocomposites

Poly(methyl methacrylate)/titanium dioxide (PMMA-g-TiO2) nanocomposites were prepared by the direct esterification reaction under mild conditions. Initially, the surface of titanium dioxide nanoparticles (TiO2 NPs) was modified by 3-glycidoxypropyl trimethoxysilane in order to prepare epoxy functionalized TiO2 NPs. The nanoparticles were refluxed in ethanol solution of HCl to convert the epoxy groups into alkyl-hydroxyl units. Subsequently, PMMA chains were attached to the surface of TiO2 NPs by the esterification reaction between alkyl-hydroxyl units at the nanoparticle surface and carboxylic acid terminated PMMA. Fourier transformed infrared spectrometry confirmed the presence of PMMA groups grafted on the surface of TiO2 NPs. X-ray diffraction and X-ray photoelectron spectroscopy revealed the existence of the grafted PMMA of the nanocomposites. An improved thermal property of the nanocomposites was observed by thermogravimetric analysis while transmission electron microscopy images confirmed well dispersed nanocomposites in chloroform due to the functionalization of PMMA brushes.

Direct grafting imidazolium-based poly(ionic liquid) onto multiwalled carbon nanotubes via Diels-Alder “click” reaction

ABSTRACT A facile route for grafting poly(ionic liquid)s (PILs) on to the surface of multi-walled carbon nanotubes (MWNTs) was demonstrated via Diels-Alder (DA) “click” reaction. Firstly, block copolymers of poly(chloromethylstyrene-alt-maleic anhydride) (PCMA) were prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization. The anhydride units in the copolymer were functionalized with furfuryl amine and then the chloromethyl groups were subsequently tailored with 1-methylimidazole, which afforded imidazolium-based PILs bearing pendent furan moieties. The PILs chains were covalently anchored to the surface of MWNTs, affording PILs/MWNTs by the DA reaction in water under ultrasound assistance. The obtained hybrid materials were characterized by TGA, FT-IR, and TEM analysis. The PILs/MWNTs could be well dispersed in water and organic solvents for several months.