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Here, we report a new facile method to improve both the conductivity and alkaline stability of AEMs by directly growing poly(ionic liquid) from BrPPO and Br@CNTs via one-pot simultaneous ARGET ATRP and the following ionizing co-crosslink.

In this paper, a poly(methyl methacrylate)-block-poly(ethylene glycol methacrylate) [PMMA-b-P(PEGMA)] copolymer is synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerizat...

Folic acid is an important biological compound for human disease diagnosis. Traditional detection methods of folic acid are mostly time-consuming or dependent on analytical equipment. Here we demonstrate the rapid and colorimetric detection of folic acid using a novel colorimetric sensor enabled by molecularly imprinted photonic hydrogels, which are prepared by the polymerization of precursor solution in the interstitial voids of the polystyrene colloidal crystal and subsequent removal of colloidal crystal and folic acid molecules. As folic acid is instable under the preparation process of molecularly imprinted photonic hydrogels, we introduce folic acid (imprinted molecule) in the form of supramolecular complex with β-CD units to improve its stability and further create stable molecular recognition sites. The folic acid recognition can be directly transferred into a visually perceptible color change due to the highly ordered macroporous structure. With this novel sensory system, the highly selective, high sensitive (as low as 10–12 M), and rapid response (

In this work, the thiolized attapulgite (ATP-MTS) particles were prepared by the dealcoholation between hydroxyl and γ-mercaptopropyltrimethoxysilane (MTS). Then, based on the ‘grafting from’ mecha...

The present work aimed to develop polyvinyl alcohol (PVA) hydrogel films with physically crosslinking through controllable entanglement density of the polymer chains. The viscoelasticity of PVA aqueous solutions was investigated over a broad range in molecular weight. The chain length between the crosslinks in the hydrogel (Me¯) and entanglement density was determined by the plateau modulus (G'). The value of (Me¯) increased with the PVA molecular weight, which can be attributed to the enhanced entanglement associated with the hydrogen bonds between inter‐ and interchains. The melting and crystallization of the transparent PVA hydrogel films showed that the crystallinity was below 30%, which indicated that microcrystallites formed. Therefore, the entanglement effect and microcrystallization enhanced the stable crosslinked hydrogel network, which further improved by an increase in the molecular weight. Altogether, the PVA with the molecular weight higher than 88,000 g/mol can be envisioned as a promising material for preparing the hydrogel film possessing excellent performance. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1673–1683

Surface modification of azide-decorated multiwalled carbon nanotubes (MWCNTs) with well-defined alkyne-terminated poly(methyl methacrylate) (PMMA) chains was accomplished via the combination of reversible addition fragmentation chain transfer (RAFT) and “click” chemistry. Successful attachment of PMMA onto MWCNT was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), gel permeation chromatography, Raman spectroscopy, and transmission electron microscopy. The highest grafting percentage (GP) of the PMMA chains (GP = 23.3%) was calculated using TGA. The effect of the PMMA-grafted-MWCNTs (MWCNTs-g-PMMA) content on the performance of the poly(vinylidene fluoride) (PVDF)-MWCNTs-g-PMMA composite membrane was studied. The MWCNTs-g-PMMA was found to be well dispersed in the PVDF composite membrane matrix because of the excellent compatibility between the PMMA and PVDF chains. The composite membranes showed improved porosity, hydrophilicity, water flux, β-PVDF content, and mechanical properties at an optimal amount of 2 wt% MWCNTs-g-PMMA incorporated in the PVDF membrane matrix. In contrast, the hydroxyl functionalized MWCNTs (MWCNTs-OH) showed limited enhancement in the water flux and mechanical strength, which is mainly due to the poor dispersion of MWCNT because of the weak interaction between the MWCNT and PVDF chains. This study reveals the excellent prospect of the MWCNT-based ultrafiltration membrane with enhanced properties in water treatment applications.

The National Free Antiretroviral Therapy (ART) Program in China has initiated to provide ART to HIV-1 patients, which has acted as an efficient method to suppress viral replication and helps prevent onward transmissions. But the problems of HIV drug resistance (HIVDR) may also come along. There is little data on the prevalence of HIVDR in Chengdu, where the number of HIV/AIDS patients ranks first among provincial capitals. Therefore, epidemiological surveillance was conducted in this area. From 2014 to 2016, HIV/AIDS patients (15 years and older) who had received first-line ART for at least six months were enrolled. Demographic, behavioral information and medical history were recorded, and blood samples were collected for viral loads and immune cell count analyses. HIV-1 pol was obtained for HIV-1 subtypes and drug resistance-associated mutations (DRMs) among virologic failure patients. A total of 13,782 individuals were enrolled, and 481 samples were sequenced for subtypes and drug resistance analysis. Six subtypes were identified, among which CRF01_AE (54.3%) and CRF07_BC (41.6%) were the dominant subtypes, and CRF55_01B (0.4%) was detected in Chengdu for the first time. The prevalence of HIVDR in treatment-experienced patients was 1.8%, with 1.2% to nucleoside reverse transcriptase inhibitors (NRTIs), 1.7% to non-NRTIs (NNRTIs), and 0.14% to protease inhibitors (PIs). The leading DRMs observed in the study were M184I/V (59.59%) against NRTIs and K103N (37.55%) against NNRTIs. This study focused on the HIVDR surveillance among patients receiving treatment in Chengdu. The overall prevalence of HIVDR was relatively low among treated patients. These findings were believed to be contributed to an understanding of HIV-1 subtypes, HIVDR prevalence, and DRMs in Chengdu and thereby optimizing clinical management, prevention, and control of HIV.

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In this work, we proposed the tuning of the interface between attapulgite (ATP) and polycarbonate (PC) by the surface tailoring of ATP via a combination of RAFT polymerization and alkynyl-thiol click reaction. The side alkynyl-functionalized random copolymer poly(MMA-co-PgMA) was synthesized as the immobilization block via redox-initiated room-temperature RAFT copolymerization of MMA and propargyl methacrylate (PgMA). Then, the dispersion block was synthesized by room-temperature RAFT polymerization of MMA using poly(MMA-co-PgMA) as the macro chain transfer agent to afford poly((MMA-co-PgMA)-b-MMA). FTIR, 1H NMR, gel permeation chromatograph (GPC), and kinetic results indicated the successful synthesis of copolymers with well-defined structures. Copolymers with different length of PMMA segment were tethered onto the surface of thiol-functionalized ATP via alkynyl-thiol click reaction to mediate the interfacial interaction between ATP and PC, the successful covalent grafting of copolymers was confirmed by FTIR, TGA, XPS and XRD, and the effects of dispersion blockchain length on nanocomposites were investigated. The functionalized ATP demonstrated an improved dispersity in nanocomposites and enhanced mechanical properties with increasing dispersion blockchain length. The PC nanocomposites with functionalized ATP showed lower Tg and complex viscosity as compared to that of pure PC and nanocomposites with bare ATP, which enhanced the processability of nanocomposites.

Nanoclay attapulgite (ATP) was first activated with hydrochloric acid to enhance the surface reactivity, and was then allowed to react with a synthetic aromatic tertiary amine coupling agent to introduce electron-donor groups. Subsequently, the surface-initiated reversible addition–fragmentation chain transfer (SI-RAFT) polymerization of methyl methacrylate (MMA) was carried out in the presence of a free RAFT agent cyanoisopropyl dithiobenzoate (CPDB) initiated by a redox pair made up of benzoyl peroxide (BPO) and aromatic tertiary amine functionalized ATP (ATP-ATA). The grafting process was verified by 1H nuclear magnetic resonance, UV-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermo gravimetric analysis, transmission electron microscopy and gel permeation chromatography. Kinetic behavior indicated that polymerization using this redox initiation system displayed a living/controlled nature. Both the grafted and free polymers were grown in a controlled manner, and the RAFT polymerization proceeded with 37.6% monomer conversion achieved within 10 h at 50 °C, yielding about 47.4% grafting ratio of polymer relative to hybrid particles with high affinity to organic media.

The surface grafting of attapulgite (ATP) with polystyrene (PS) was established via a simultaneous reverse and normal initiation atom transfer radical polymerization (SR&NIATRP). 4-(chloromethyl)phenyltrimethoxysilane (CMPTMS) chemical bounded on the surface of ATP (ATP-Cl, Cl-I) was prepared via one-step self-assembly. SR&NI ATRP of styrene was conducted using CuCl2 complex tris(2-(dimethylamino)ethyl)amine (Me6-TREN) as the catalytic system, initiated by 2,2-azobis(isobutyronitrile) (AIBN) and ATP-Cl. FT-IR, XRD, XPS, TGA and TEM data were consistent with the grafting of benzyl chloride groups and PS chains on ATP surface. The controllability of polymerization was investigated by the kinetics behavior under different molar ratio of AIBN and CuCl2. The obtained polymer possessed a uniform distribution of molecular weights with a lower polydispersity index of 1.2∼1.4. The relationship between polymerization on the surface of ATP and in solution was discussed in detail based on TGA data of hybrid particles and GPC trace of free polymer in solution. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015

In this work, we employed the nonsolvent induced phase separation (NIPS) combined with the gelation method to prepare poly(vinylidene fluoride) (PVDF) membranes. The mixture of N,N-dimethylformamide (DMF) and γ-Butyrolactone (γ-BL) was used as a solvent, and water was used as a nonsolvent. Membrane changed from a cellular to spherulitic morphologies simply by varying the mass ratio of DMF/γ-BL and the PVDF concentration. On quenching the casting solution (with 15 wt% PVDF concentration) in the water bath, the membrane had a uniformly cellular morphology, which resulted from a typical liquid–liquid (L-L) phase separation. At higher PVDF concentrations (≥20 wt%), membranes presented a spherulitic structure, arising from a solid–liquid (S-L) phase separation. The crystallization behavior and crystalline form of the PVDF membrane were identified by different scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), respectively. For the 15 wt%-PVDF membrane gained from the mixed solvent with a mass ratio of DMF/γ-BL = 8/2, the highest tensile strength (7.3 MPa) and elongation at break (223%) was obtained.

Poly(methyl methacrylate) brushes grafted from attapulgite nanoparticles (ATP@PMMA) were prepared by R-Supported reversible addition-fragmentation chain transfer polymerization (RAFT). ATP was firstly activated, and allowed to react with γ-aminopropyltriethoxysilane (APTES), 4,4′-azobis(4-cyanovaleric acid) (ACVA) and bis(thiobenzoyl) disulfide stepwise to afford 4-cyanopentanoic acid dithiobenzoate functionalized ATP (ATP-CPADB). Then, RAFT polymerizations of MMA mediated by the different systems were conducted and compared systemically. The grafting process was verified by FTIR, XRD, XPS, TGA and TEM data. Kinetic behavior indicated that the anchored CPADB is more effective before diffusing into the bulk phase. The grafting ratio (G r), while M n of grafted and free polymer increased linearly with increasing monomer conversion in presence of free CPADB, giving the hybrid particles with more homogeneous distribution of grafted polymer layer.

An efficient synthesis route was developed for the preparation of multiwalled carbon nanotube (MWCNT) nanohybrids using azide-terminated poly(methyl methacrylate) (PMMA) via a combination of reversible addition fragmentation chain transfer (RAFT) and the click reaction. A novel azido-functionalized chain transfer agent (DMP-N3) was prepared and subsequently employed to mediate the RAFT polymerizations of methyl methacrylate (MMA). The RAFT polymerizations exhibited first-order kinetics and a linear molecular weight dependence with the conversion. The kinetic results show that the grafting percentage of PMMA on the MWCNTs surface grows along with the increase of the reaction time. Even at 50 &deg, C, the grafting rate of azide-terminated PMMA is comparatively fast in the course of the click reaction, with the alkyne groups adhered to MWCNTs in less than 24 h. The successful functionalization of PMMA onto MWCNT was proved by FTIR, while TGA was employed to calculate the grafting degree of PMMA chains (the highest GP = 21.9%). Compared with the pristine MWCNTs, a thicker diameter of the MWCNTs-g-PMMA was observed by TEM, which confirmed the grafted PMMA chain to the surface of nanotubes. Therefore, the MWCNTs-g-PMMA could be dispersed and stably suspended in water.

Lactic acid bacteria (LAB) are generally regarded as safe (GRAS) microorganisms and widely used in industry and medicine. We are trying to add additional properties to them by gene engineering. However, the genetically modified bacteria are not acceptable to use in food and medicine due to the presence of antibiotic resistance genes in plasmids. Thus, it is necessary to develop food-grade selection markers. Food-grade markers can be divided into three classes based on their selected characteristics: dominant, complementary and sugar fermentation markers. The developments on these food-grade selection markers were reviewed in order to provide valuable references for the further study. [TAF Prev Med Bull 2012; 11(4.000): 499-510]

A simple method by the decomposition of tetra-cis-9-octadecenoic germanium in thermal solvent was developed to prepare germanium nanowires with different diameters. Electrical transport measurements showed that larger diameter size Ge nanowires displayed good ohmic contact with metal electrodes while the nonohmic contact behavior was displayed between smaller diameter Ge nanowires and metal electrodes. The surface of these synthesized Ge nanowires has very high reactivity, the rough surface of Ge nanowires can be used as a center of nucleation for the growth of ZnO nanowires. The trace amount of Ge present in the nanowires, which could provide the green luminescence by either donor–acceptor pair or donor–hole recombination.

Isotropical conductive adhesives (ICAs) have recently received a lot of focus and attention from the researchers in electronic industry as a potential substitute to lead-bearing solders. In this paper, a novel kind of isotropical conductive adhesives was made by using silver (Ag) nanowires and nanosized silver particles as conductive fillers. These Ag nanowires with dismeters in the range of 30-50 nm and lengths of up to ~ 50 mum could be synthesized by a solution-phase method, which was proceed by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP). Electrical property including bulk resistivity and mechanical property including shear strength were investigated and compared with that of conventional ICA filled with micrometer-sized Ag particles or nanometer-sized Ag particles. Our results indicated that ICA filled Ag nanowires exhibited higher conductivity, higher shear strength and low percolation threshold value than traditional ICA. Possible conductive mechanism was discussed based on theory calculation.

Cancer poses a tremendous therapeutic challenge worldwide, highlighting the critical need for developing novel therapeutics. A promising cancer treatment modality is gene therapy, which is a form of molecular medicine designed to introduce into target cells genetic material with therapeutic intent. The history of RNA interference (RNAi) has only a dozen years, however, further studies have revealed that it is a potent method of gene silencing that has developed rapidly over the past few years as a result of its extensive importance in the study of genetics, molecular biology and physiology. RNAi is a natural process by which small interfering RNA (siRNA) duplex directs sequence specific post-transcriptional silencing of homologous genes by binding to its complementary mRNA and triggering its elimination. RNAi has been extensively used as a novel and effective gene silencing tool for the fundamental research of cancer therapeutics, and has displayed great potential in clinical treatment.

Uniform-sized monodisperse cerium dioxide nanocubes with 20–120 nm edge lengths can be synthesized by an inexpensive microwave-assisted method. This is based on the oxidation and then decomposition of cerium (III) nitrate aqueous solution under a basic environment. The high energy emitted by microwave irradiation at a short time can promote the reaction and the crystallization process simultaneously. Both shape and size of the cerium oxide could be tuned more conveniently by changing the concentration of surfactant in the solution and the power of the microwave irradiation. The morphology and crystal structure of cerium dioxide nanocubes obtained at different conditions were characterized by high-resolution transmission electron microscope, X-ray diffraction and selected area electron diffraction.

The dynamics of transportation, accumulation, disappearance and distribution of 60 Co in a simulated aquatic-terrestrial ecosystem was studied by isotope-tracer technique. In the aquatic system, 60 Co was transported and transformed via depositing, coupling with ions and adsorption. The absorption resulted in the redistribution and accumulation of 60 Co in each compartment of the system. Specific activities of 60 Co in water started sharply and gently decreased. The sediment accumulated a large amount of 60 Co by adsorption and ion exchange. The hornwort (Ceralophyllum demersum) could also adsorb a large amount of 60 Co in a short time, because of its large specific surface area. Fish (Carassius auratus) and snail (Bellamya purificata) had a poor capacity of adsorbing 60 Co. The distribution of 60 Co in the fish was mainly in the viscera, and the amount of 60 Co in the snail flesh was greater than that in the shell. The amount of 60 Co in individual compartment in the system was changed with time. The highest specific activity of 60 Co in the bean of the terrestrial system remained in the root nodule.

Hybrid nanocomposites consisting of polydimethylaminoethyl methacrylate (PDMAEMA) and attapulgite (ATP) were prepared by using a surface thiol-Ce (IV) redox initiation system via graft from approach. Initially, ATP was chemically modified with γ-mercaptopropyltrimethoxysilane (MTS) to anchor thiol groups on the surface (ATP-MTS). Subsequently, surface-initiated polymerization of dimethylaminoethyl methacrylate was performed by using ATP-MTS and cerium (IV) ammonium nitrate (CAN) in aqueous nitric acid (HNO3) to afford hybrid particles (ATP-g-PDMAEMA). Evidence of grafting of PDMAEMA was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Thermogravimetric Analysis (TGA). The crystal structure of PDMAEMA grafted ATP was characterized by X-ray diffraction (XRD) analysis. Morphology of ATP-g-PDMAEMA was observed by transmission electron microscopy (TEM). The effects of concentration of Ce (IV), HNO3, and reaction temperature were examined by determining the percentage of grafting (PG). With other condition kept constant, the optimum conditions were obtained as follows: the reaction temperature was 50°C, Ce (IV) and HNO3 concentrations were 12.5 mmol/L and 1 mol/L, respectively, when 0.2 g of ATP-MTS, 1 mL of DMAEMA, and 4 mL of aqueous solution were used. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42762.

The Core-shell hybrid particles with attapulgite (ATP) as the core and polymethylmethacrylate (PMMA) as the shell (ATP-g-PMMA) were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization method. The diameter of ATP-g-PMMA was increased to 50–60 nm, and the surface hygroscopicity was decreased observably after surface grafting. Then, ATP-g-PMMA hybrid particles were filled into the polycarbonate (PC) by melt mixing to afford nanocomposites, and the mechanical properties, microstructures, thermal stability, and rheological behavior of nanocomposites were investigated by varying ATP-g-PMMA concentration in the range 1, 3, 5, and 7 wt % in PC. Fourier Transform infrared spectroscopy (FTIR) suggested that there is no esterification reaction between particles and matrix. Slight changes in tensile strength, and noticeable decrease of elongation and impact strength were observed with the increase in ATP-g-PMMA particles loading. The morphology evaluated by field-emission scanning electron microscopy (FESEM) indicated that ATP-g-PMMA was dispersed with a diameter range of 80–100 nm, and phase separation was appeared with increasing ATP-g-PMMA loadings. Thermogravimetric analysis (TGA) results revealed the thermal stability of composites was strengthened. The disentanglement and interface slip induced by preferred orientation and directional arrangement of ATP-g-PMMA resulted in lower complex viscosity (η*) and higher loss factor (tan δ) compared with the pristine PC. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42262.

A series of polymer–clay nanocomposites consisting of polystyrene (PS) and attapuglite (ATP) were prepared successfully. First, silane coupling agent containing aromatic tertiary amine groups was synthesized to functionalize ATP (M-ATP). Then, PS nanocomposites with varied clay loadings were prepared via in situ suspension polymerization process with a redox initiation system consisting of aromatic tertiary amine and benzoyl peroxide. The synthesis of silane coupling agent and functionalization of ATP were confirmed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectra, and X-ray photoelectron spectroscopy. Mechanical properties, morphology, thermal stability, and rheological behavior of nanocomposites were investigated to illuminate the effects of M-ATP on the structure and properties of nanocomposites. Field-emission scanning electron microscope images revealed an ideal dispersion of M-ATP and an enhanced toughness of nanocomposites. The improved interface interaction between M-ATP and PS matrix endowed the nanocomposites with outstanding mechanical properties and thermal stability. The formation of hybrid network in the nanocomposites containing 3 wt % M-ATP resulted in higher complex viscosity (η*), storage modulus (G′), and lower loss factor (tanδ) compared with the pristine PS and PS/ATP nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41567.

Poly(methyl methacrylate) (PMMA) was bonded on the surface of attapulgite (ATP) by using an ammonium persulfate amine redox initiation system via grafting from approach. ATP was modified with (3-aminopropyl)triethoxysilane to anchor amine groups on the surface, and then the amine-functionalized ATP was further treated with methacryloyl chloride and 4,4′-azobis(4-cyanovaleric acid) to give methacryl- and azo-functionalized ATP, respectively. Subsequently, surface-initiated graft polymerization of MMA in a soap-free emulsion was performed to afford ATP/PMMA hybrids. Meanwhile, graft polymerizations on the surface of methacryl- and azo-functionalized ATP were carried out for comparison. The grafting of PMMA on the surface of ATP was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis (TGA). The crystal structure of hybrids was characterized by X-ray diffraction analysis. The morphology of hybrids was observed by scanning electron microscopy and transmission electron microscopy. The degree of grafting obtained from surface-initiated graft polymerization in a soap-free emulsion was found to be the greatest (29.4%) estimated from TGA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41062.

Novel high density polyethylene (HDPE)/SiO2 hybrid materials were prepared by the sol–gel process using tetraethoxysilane (TEOS). HDPE and synthesized HDPE-g-vinyl trimethoxysilane (VTMS) through melt grafting method was used as the raw material. The structure and thermal, mechanical properties of hybrid materials were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), simultaneous thermogravimetric (TG), differential thermal analysis (DTA), and tensile tests, respectively. Silica phase in the HDPE-g-VTMS hybrids showed a network structure and nano-scale size. The covalent bonds between organic and inorganic phases were introduced by the HDPE-g-VTMS bearing trimethoxysilyl groups, which underwent hydrolytic polycondensation with TEOS. The thermal stability and mechanical properties of HDPE-g-VTMS hybrids were obviously improved by embedded silica networks. It was found that the silica content in the HDPE-g-VTMS hybrid material was linearly increased with the TEOS dosage. The formation of the HDPE-g-VTMS hybrid was beneficial for enhanced mechanical strength and thermal stability, in comparison with the neat HDPE. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39891.