Synthesis and Characterization of Poly (Methyl Methacrylate)/Polyethylenimine Grafting Core-Shell Nanoparticles for CO2 Adsorption Using Soap-Free Emulsion Copolymerization

Unlike previous emulsion polymerization, we used grafting reactions in soap-free emulsion systems. In this study, we synthesized grafted PMMA/PEI core-shell nanoparticles by varying the MMA/PEI content and molecular weight of PEI (Mn = 600, 8000, and 10,000). The size and morphology of the core-shell nanoparticles were characterized by a particle size analyzer and scanning electron microscopy. The nanoparticles were 178 - 408 nm in diameter and swelled in water or methanol by 30 - 75 nm. The size of the nanoparticles increased with MMA contents, whereas the size distribution progressively became homogeneous with increasing molecular weight of PEI. Lastly, we measured CO2 adsorption capacity of the grafted PMMA/PEI core-shell nanoparticles, and we found the capacity to be limited at a level of 0.69 mg, which occurred for nanoparticles prepared from emulsions at a pH value of 11.

Preparation and Properties of Zirconium Hydrideon the surface of MCM-41 Mesoporous Molecular Sieves

Zirconium monohydride bonded to the framework oxygen of MCM-41 surface was prepared by the reaction of tetraneopentyl zirconium with MCM-41 surface hydroxyl groups, followed by the hydrogenolysis of the resulted product. The surface hydride was characterized by using infrared spectroscopy, solid-state NMR, elemental analysis, gas-phase chromatography and chemical probing reaction. It was shown that this surface species is stable below 150 ’C and can catalytically crack alkanes into methane and ethane at 100 .

Allyl-containing Poly(aryl ether sulfone): Synthesis and Crosslinking

A novel type of crosslinkable poly（aryl ether sulfone）（PAES） bearing an allyl pendant（PES-OAllyl） was synthesized by a grafting reaction of hydrophenyl-containing PAES（PES-OH） and allyl bromide. PES-OH was prepared by a demethylation reaction of a methoxyphenylated PAES（PES-OCH3） in the presence of pyridine/hydrochlo- ride. The PES-OCH3 was synthesized by an aromatic nucleophilic substitution of bis（4-chlorophenyl）sulfone and （p-methoxy）phenylhydroquinone. Both DSC and solubility investigation were used to study the crosslinking behavior of PES-OAllyl. After heat treatment, the glass transition temperature（Tg） value of PES-OAllyl sharply increased from 165 ℃ to 227 ℃. Meanwhile, PES-OAllyl changed from a soluble polymer to an insoluble thermoset. In addition, TGA（thermogravimetric analysis） result suggests that the thermal stability of the crosslinked product was improved. All the data prove that the crosslinked PES-OAllyl could be a potential solvent-resistance high-performance material.

Synthesis and characterization of star-comb polybutadiene and poly(ethylene-co-butene)

A novel star-comb polybutadiene(SC-PB) was synthesized with n-butyllithium(n-BuLi) as initiator,epoxidized star liquid polybutadiene(ESPB) as coupling agent,cyclohexane as solvent by living anionic polymerization and grafting-onto technology. The SC-PB was subsequently hydrogenated by homogeneous catalysis(catalytic hydrogenation using nickel naphthenate/ triisobutyl aluminum),to transform the SC-PB into the corresponding star-comb poly(ethylene-co-butene)(SC-PEB).The SC-PB was characterized by SEC-TALLS,~1...

Modification of Sepiolite by Treatment with Methyl Triethoxysilane

Grafting reaction of methyltriethoxysilane on sepiolite surface was studied.The structure of the silanized product before and after thermal treatment was characterized by XRD,TG-DTA,SEM and IR.It is found that the silicon monomers are grafted on the external surface of sepiolite via silicon hydroxyls.The thermal stability remains unchanged after silanization.

Quantitative chimerism kinetics in relapsed leukemia patients after allogeneic hematopoietic stem cell transplantation

Background Chimerism analysis is an important tool for the surveillance of post-transplant engraftment. It offers the possibility of identifying impending graft rejection and recurrence of underlying malignant or non-malignant disease. Here we investigated the quantitative chimerism kinetics of 21 relapsed leukemia patients after allogeneic hematopoietic stem cell transplantation （HSCT）. Methods A panel of 29 selected sequence polymorphism （SP） markers was screened by real-time polymerase chain reaction （RT-PCR） to obtain the informative marker for every leukemia patient. Quantitative chimerism analysis of bone marrow （BM） samples of 21 relapsed patients and 20 patients in stable remission was performed longitudinally. The chimerisms of BM and peripheral blood （PB） samples of 14 patients at relapse were compared. Results Twenty-one patients experienced leukemia relapse at a median of 135 days （range, 30-720 days） after transplantation. High recipient chimerism in BM was found in all patients at relapse, and increased recipient chimerism in BM samples was observed in 90% （19/21） of patients before relapse. With 0.5% recipient DNA as the cut-off, median time between the detection of increased recipient chimerism and relapse was 45 days （range, 0-120 days）, with 76% of patients showing increased recipient chimerism at least 1 month prior to relapse. Median percentage of recipient DNA in 20 stable remission patients was 0.28%, 0.04%, 0.05%, 0.05%, 0.08%, and 0.05% at 1, 2, 3, 6, 9, and 12 months, respectively, after transplantation. This was concordant with other specific fusion transcripts and fluorescent in situ hybridization examination. The recipient chimerisms in BM were significantly higher than those in PB at relapse （P=-0.001）. Conclusions This SP-based RT-PCR assay is a reliable method for chimerism analysis. Chimerism kinetics in BM can be used as a marker of impending leukemia relapse, especially when no other specific marker is available. Based on our findings, we recommend examining not only PB samples but also BM samples in HSCT patients.

α-Fe2O3 immobilized benzimidazolium tribromide as novel magnetically retrievable catalyst for one-pot synthesis of highly functionalized piperidines

Nanostructured ot-Fe2O3 were prepared by precipitation followed by calcination method. Cetyltrimethylammonium bromide （CRAB） was used as surfactant. The nano α-Fe2O3 was then silanized with （3-chloropropyl）-triethoxysilane （CPTES） by room temperature mixing ofα-Fe2O3 and CPTES to produce silane coated ct-Fe2O3 （CIPr-Si@Fe2O3）. As-synthesized CIPr-Si@Fe2O3 was functionalized via covalent grafting of benzimidazole to produce 3-（1-benzimidazole）Pr-Si@Fe2O3. This was further reacted with bromine to afford α-Fe2O3 immobilized benzimidazolium tribromide （α-Fe2O3-BIM tribromide）. This ionic liquid （IL） α-Fe2O3 BIM tribromide was characterized by FT-IR, XRD, TEM, SEM, TGA, VSM, EDX and BET analysis. The as-synthesized IL tribromide was used as catalyst for one-pot synthesis of highly substituted piperidines. The method is greener in terms of solvent selection, recovery of the catalyst and efficiency.

Photo-induced Synthesis and Characterization of Poly(methyl methacrylate) Grafted Sodium Salt of Partially Carboxymethylated Guar Gum

Photo-induced graft copolymerization of methyl methacrylate（MMA） onto sodium salt of partially carboxymethylated guar gum（Na-PCMGG, DS = 0.291） was carried out in an aqueous medium using ceric ammonium nitrate（CAN） as photoinitiator to synthesize a novel graft copolymer, Na-PCMGG-g-PMMA, which may find its potential application as a metal adsorbent. The influences of synthesis variables such as concentrations of photoinitiator（CAN）, nitric acid and monomer（MMA） as well as reaction time, temperature and amount of substrate on the grafting yields were studied and the reaction conditions for optimum photo-grafting were evaluated. At optimum concentration, the maximum values of the grafting yields achieved were G = 271.61% and GE = 63.89%. The experimental results were found to be in very good agreement with the proposed kinetic scheme. The photo-graft copolymerization of MMA onto Na-PCMGG（ DS = 0.291） was also carried out in the presence and absence of ultraviolet radiation for studying the efficiency of the photoinitiator. The influence of carboxymethyl groups introduced onto the guar gum molecules with regard to its behavior towards ultra-violet radiation induced grafting with MMA was also investigated. Photo-grafting process was confirmed and the products were characterized with the help of the spectroscopic（1H-NMR and FTIR） and SEM techniques.