Nano‐emulsion use for the synthesis of polyaniline nano‐grains or nano‐fibers

We report that nano‐emulsions can be creatively used as a morphology selective synthesis method to prepare not only nano‐grains but also nano‐fibers with high selectivity. Synthesis of the two different morphological materials was demonstrated using polyaniline synthesis as a model case. Polyaniline nano‐grains were synthesized from aniline molecules in nano‐size aqueous droplets as polymerization sites whose droplets were generated by inverse water‐in‐oil nano‐emulsion use, and polyaniline nano‐fibers were synthesized from aniline in aqueous nano‐dimensional channels as polymerization sites whose channels were generated by direct oil‐in‐water nano‐emulsion use containing high population of oil droplets. Using the approaches, we successfully synthesized nano‐fibers of 60 nm diameter with 0.5 µm length and also nano‐grains having diameter of 60–80 nm. The two different polymerization sites of nano‐scale dimension were made by changing the ratio among surfactant, aqueous aniline/HCl solution, and oil, i.e. organic solvent. We found the nano‐fibers synthesized from the channels formed by the direct oil‐in‐water nano‐emulsion have higher bulk electrical conductivity than the nano‐grains which were synthesized from the droplets formed by the inverse water‐in‐oil emulsion. We also found that the emulsion use allows us to use a room temperature synthesis unlike conventional synthesis methods which require to use ice bath temperature. Physical properties of both nano‐fibers and nano‐grains synthesized were characterized by Fourier transform infrared (FTIR), UV–Vis spectra, scanning electron microscopy (SEM), and four probes conductivity measurement. Copyright © 2009 John Wiley & Sons, Ltd.     

pH‐responsive starch microparticles for a tumor‐targeting implant

Much progress has been made toward stimuli‐responsive polysaccharide‐based selective tumor therapy not only because polysaccharides have nontoxic biodegradability and biocompatibility but also because their stimuli‐sensitive characteristics enable the proper transport of payloads into tumors. Here, we attempted to deliver an antitumor drug, doxorubicin (DOX), using starch‐based microparticles coupled with pH‐responsive 3‐(diethylamino)propylamine. The microparticles of starch conjugated with 3‐(diethylamino)propylamine (SDEAP) allowed for the change in hydrophobicity of SDEAPs in a pH‐dependent manner. The results revealed that SDEAPs effectively carried and released DOX and selectively killed tumor cells under acidic condition. Overall, this study suggests that DOX‐loaded SDEAPs can be further explored as a strategy for applications to acidic tumor‐targeting implants owing to the drug‐deliver efficiency and tumor selectivity.     

Synthesis and characterization of folic acid‐modified carboxymethyl chitosan‐ursolic acid targeted nano‐drug carrier for the delivery of ursolic acid and 10‐hydroxycamptothecin

Carboxymethyl chitosan (CMCS), as a water‐soluble, biocompatible, and biodegradable polymer, is an excellent carrier for a sustained drug delivery system. In this study, a amphiphilic carboxymethyl chitosan‐ursolic acid nano‐drug carrier modified by folic acid (FPCU) were prepared, and then the nano‐drug carrier wrapped another anticancer drug 10‐hydroxycamptothecin were self‐assembled into nanoparticles (FPCU/HCPT NPs). The FPCU/HCPT NPs had a suitable size, high drug loading efficiency of ursolic acid (6.4%) and 10‐hydroxycamptothecin (14.1%). The drug release study in vitro indicated that the nanoparticles have obviously sustained effect and pH sensitive behaviors, the drug release amount was higher at pH 5.5 than at pH 7.4. in vitro and in vivo study showed that the nanoparticles displayed a high antitumor efficiency to tumor cells compared with free drug. The nano delivery system as a carrier for ursolic acid (UA) and 10‐hydroxycamptothecin (HCPT) has good application prospects in cancer treatment.     

Improvement in gas separation properties of a polymeric membrane through the incorporation of inorganic nano‐particles

The present work tries to introduce a high‐performance nano‐composite membrane by using polydimethylsiloxane (PDMS) as its main polymer matrix to meet some specific requirements in industrial gas separations. Different nano‐composite membranes were synthesized by incorporating various amounts of nano‐sized silica particles into the PDMS matrix. A uniform dispersion of nano‐particles in the host membranes was obtained. The nano‐composite membranes were characterized morphologically by scanning electron microscopy and atomic force microscopy. Separation properties, permeability, and ideal selectivity of C₃H₈, CH₄, and H₂ through the synthesized nano‐composite membranes with different nano‐particle contents (0.5, 1, 1.5, 2, 2.5, and 3 wt%) were investigated at different pressures (2, 3, 4, 5, 6, and 7 atm) and constant temperature (35°C). It was found out that a 2 wt% loading of nano‐particles into the PDMS matrix is optimal to obtain the best separation performance. Afterwards, sorption experiments for the synthesized nano‐composite membranes were carried out, and diffusion coefficients of the gases were calculated based on solution‐diffusion mechanism. Gas permeation and sorption experiments showed an increase in sorption and a decrease in diffusion coefficients of the gases through the nano‐composite membranes by adding nano‐particles into the host polymer matrix. Copyright © 2011 John Wiley & Sons, Ltd.     

Mechanical and electrical properties of the phosphor‐doped nano‐silicon film under an external electric field

The mechanical and electrical properties of the phosphor‐doped nano‐silicon film (nc‐Si:H) prepared by the plasma‐enhanced chemical vapor deposition (PECVD) method under electric field have been studied by Tribolab system, which is equipped with nano‐electrical contact resistance (ECR) tool. During indentation, different voltages and loads were applied. The topography of the sample surface was studied by atomic force microscopy (AFM). The experimental results show that the roughness of the film is 5.69 nm; the electric current was measured through the sample/indenter tip with different loads at a fixed voltage, and it increased nonlinearly during the indentation. The maximum current value depth was shallower than the maximum depth of each indent due to the plasticity of the film. When the loading speed is increased to 250 µN/s, the microcrack occurred on the film; the hardness (H) and elastic modulus (E) changed with the voltage applied both in open circuit and in short circuit case, which resulted in different values of H/E rate from 0.082 to 0.096. Copyright © 2009 John Wiley & Sons, Ltd.     

Boehmite nano‐particles functionalized with silylpropylamine‐supported Keggin‐type heteropolyacids: Catalysts for epoxidation of alkenes

Boehmite nano‐particles with a high degree of surface hydroxyl groups were covalently functionalized by 3‐(trimethoxysilyl)‐propylamine to support H₃[PMo₁₂O₄₀], H₃[PW₁₂O₄₀], H₄[SiMo₁₂O₄₀] and H₄[SiW₁₂O₄₀] Keggin‐type heteropolyacids. After characterization of these catalysts by FT‐IR, powder X‐ray diffraction, TG/differential thermal analysis, CHN, inductively coupled plasma and transmission electron microscopy techniques, they were applied to the epoxidation of cis‐cycloocten. The progress of the reactions was investigated by gas–liquid chromatography, and the catalytic procedures were optimized for the parameters involved, such as the solvent and oxidant. The results showed that 25 mg of supported H₃[PMo₁₂O₄₀] catalyst in 1 ml C₂H₄Cl₂ with 0.5 mmol cyclooctene and 1 mmol tert‐butylhydroperoxide at reflux temperature gave 98% yield over 15 min. Recycling experiments revealed that these nanocatalysts could be repeatedly applied up to five times for a nearly complete epoxidation of cis‐cycloocten. The optimized experimental conditions were also used successfully for the epoxidation of some other alkenes, such as cyclohexene, styrene and α‐methyl styrene.     

Self‐Assembled BolA‐like Amphiphilic Peptides as Viral‐Mimetic Gene Vectors for Cancer Cell Targeted Gene Delivery

In this study, two types of BolA‐like amphiphilic peptides with dual ligands comprising a tumor‐targeting moiety of RGD sequence and a cell‐penetrating moiety of R8 sequence are designed and synthesized as gene vectors. The BolA‐structural peptide carriers can self‐assemble into spherical nanoparticles with a hydrophilic core and shell, which are similar to the viral capsid and can bind plasmid DNA in an aqueous medium to form viral‐mimetic complexes. It is found that the BolA‐like dual ligands system exhibits significantly enhanced gene expression in both HeLa and 293T cell lines, as compared with poly(ethylenimine) PEI. These BolA‐like amphiphilic peptides are promising in clinical trials of gene therapy.

     

β‐cyclodextrin‐based polymeric nano‐receptor: the self‐assembly of cyclodextrin‐appended comb‐copolymer

Well‐defined β‐cyclodextrin (β‐CD)‐appended biocompatible comb‐copolymer ethyl cellulose‐graft‐poly (ε‐caprolactone) (EC‐g‐PCL) was synthesized via the combination of ring‐opening polymerization (ROP) and click chemistry. The resulting products were characterized by ¹H NMR, FT‐IR spectroscopy, and GPC. The synthesized comb‐copolymer could assemble to micelles, with the surface covered by β‐CD. The inclusion with ferrocene derivation was investigated by cyclic voltammetric (CV) experiments, which indicated the potential application of the micelles as nano‐receptors for molecule recognization and controlled drug release. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis of pyranopyrazoles using nano‐Fe‐[phenylsalicylaldiminemethylpyranopyrazole]Cl2 as a new Schiff base complex and catalyst

By the condensation reaction of benzaldehyde with ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of FeCl₂, a pyranopyrazole derivative was prepared which was then reacted with salicylaldehyde to afford nano‐Fe‐[phenylsalicylaldiminemethylpyranopyrazole]Cl₂ (nano‐[Fe‐PSMP]Cl₂). The prepared nano‐Schiff base complex was fully characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, differential thermogravimetry, scanning electron microscopy and UV–visible spectroscopy, and was used as an efficient and catalyst for the preparation of pyranopyrazoles.     

Cobalt ferrite encapsulated in a zwitterionic chitosan derived shell: An efficient nano‐magnetic catalyst for three‐component syntheses of pyrano[3,2‐c]quinolines and spiro‐oxindoles

A nano‐magnetic core‐shell composite fabricated of a unique zwitterionic chitosan‐derived coating and cobalt ferrite core was found to be a green and reusable heterogeneous catalyst for efficient synthesis of pyrano[3,2‐c ]quinoline and spiro‐oxindole derivatives in high to excellent yields. Due to having negative charges at its outermost layer and a high magnetization, the catalyst is finely dispersed in ethanol and can be easily separated from reaction mixtures by using a simple external magnet. It is reasonably stable as can be reused several times without appreciable loss of catalytic activity.     

Medium energy ion irradiation of Ge surface – search for a better understanding of the surface nano‐patterning

We report the morphological changes on Ge surfaces upon 50 keV Ar⁺ and 100 keV Kr⁺ beam irradiation at 60° angle of incidence. The Ge surfaces having three different amorphous–crystalline (a/c) interfaces achieved by the pre‐irradiation of 50 keV Ar⁺ beam at 0°, 30° and 60° with a constant fluence of 5 × 10¹⁶ ions/cm² were further processed by the same beam at higher fluences viz. 3 × 10¹⁷, 5 × 10¹⁷, 7 × 10¹⁷ and 9 × 10¹⁷ ions/cm² to understand the mechanism of nano‐scale surface patterning. The Kr⁺ beam irradiation was carried out only on three fresh Ge surfaces with ion fluences of 3 × 10¹⁷, 5 × 10¹⁷ and 9 × 10¹⁷ ions/cm² to compare the influence of projectile mass on surface patterning. Irrespective of the depth of a/c interface, the nanoscale surface patterning was completely missing on Ge surface with Ar⁺ beam irradiation. However, the surface patterning was evidenced upon Kr⁺ beam irradiation with similar ion fluences. The wavelength and the amplitude of the ripples were found to increase with increasing ion fluence. In the paper, the mass redistribution at a/c interface, the incompressible solid flow through amorphous layer, the angular distribution of sputtering/backscattering yields and the generation of non‐uniform stress across the amorphous layer are discussed, particularly in analogy with low energy experiments, to get better understanding of the mechanism of nanoscale surface patterning by the ion beams. Copyright © 2016 John Wiley & Sons, Ltd.     

Supported dual‐acidic 1,3‐disulfoimidazolium chlorozincate@HZSM‐5 as a promising heterogeneous catalyst for synthesis of indole derivatives

HZSM‐5‐supported Brönsted and Lewis acidic ionic solid 1,3‐disulfoimidazolium chlorozincate materials ([dsim]₂[ZnCl₄]@HZSM‐5) were synthesized with various ratios (3, 6, 9, 17 and 50% w/w). The heterogeneous materials were characterized via a variety of spectroscopic techniques. Dual acidity of these materials was determined using specified techniques. These acidic solids were examined as stable heterogeneous catalysts for the Fischer indole reaction of equimolar amounts of phenylhydrazine hydrochloride and various aliphatic or aromatic ketones at 80–90°C in neat condition to produce substituted indole derivatives. The efficient 17% ionic salt‐loaded HZSM‐5 composite was easily reused for ten consecutive cycles with a slight loss of its activity. The recycled catalyst was further analysed using powder X‐ray diffraction and inductively coupled plasma optical emission spectrometric techniques.     

A novel nano‐cotton‐like bismuth oxyfluoride (NC‐BiOF) and a novel nanosheet heterogeneous compound BiOF@ZIF‐8 as catalyst for the selective and green oxidation of benzylic alcohols

We describe here for the first time a new morphology of BiOF nanoparticles with a cotton‐like structure, made using a hydrothermal synthesis method. We also prepared heterogeneous nanosheets of BiOF@ZIF‐8 by a one‐pot synthesis under hydrothermal conditions. We demonstrate that in this method the morphology of BiOF and one‐pot synthesis conditions are the main factors for the preparation of the nanosheet BiOF@ZIF‐8. Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray (EDX), thermogravimetry‐differential thermal analysis (TG‐DTA), and BET surface area were used to characterize the samples prepared. XRD, SEM, and adsorption–desorption analysis showed that the structure of ZIF‐8 and BiOF form intact only in one‐pot synthesis of BiOF (with nano‐cotton‐like morphology) with Zn(NO₃)₃, while spectral techniques show the successful encapsulation of the sheet BiOF on ZIF‐8. Nanosheet BiOF@ZIF‐8 was found to be a highly efficient heterogeneous catalyst for the selective oxidation of alcohols. BiOF@ZIF‐8 could be reused several times although it got less active with recycling.     

A novel approach for preparation of conductive hybrid elastomeric nano‐composites

Since the discovery of carbon nanotubes (CNTs) and intrinsically conductive polymers, such as polyaniline (PANI) some research has focused on the development of novel hybrid materials by combining CNT and PANI to achieve their complementary properties. Electrically conductive elastomer nano‐composites containing CNT and PANI are described in the present investigation. The synthesis procedure includes in‐situ inverse emulsion polymerization of aniline doped with dodecylbenzene sulfonic acid in the presence of CNT and dissolved styrene‐isoprene‐styrene (SIS) block copolymer, followed by a precipitation–filtration step. The synthesis step is carried out under ultrasonication. The resulting uniform SIS/CNT/PANI dispersions are stable for long time durations. The incorporation of CNT/PANI in the SIS elastomeric matrix improves thermal, mechanical and electrical properties of the nano‐composites. The formation of continuous three‐dimensional CNT/PANI network, assumed to be responsible for enhancement of the resulting nano‐composite properties, is observed by HRSEM. A relatively low percolation threshold of 0.4 wt.% CNT was determined. The Young's modulus of the SIS/CNT/PANI significantly increases in the presence of CNT. High electrical conductivity levels were obtained in the ternary component systems. Copyright © 2013 John Wiley & Sons, Ltd.     

In situ synthesis of nano‐assemblies of the high molecular weight ferrocene‐containing block copolymer via dispersion RAFT polymerization

The in situ synthesis of the nano‐assemblies of the high molecular weight ferrocene‐containing block copolymer of poly(ethylene glycol)‐block‐poly(4‐vinylbenzyl ferrocenecarboxylate) (PEG‐b‐PVFC) via dispersion reversible addition‐fragmentation chain transfer (RAFT) polymerization was discussed. Taking the advantage of the accelerated polymerization rate of the dispersion RAFT polymerization, the nano‐objects of the well‐defined PEG‐b‐PVFC diblock copolymer with the polymerization degree (DP) of the ferrocene‐containing PVFC block up to 300 were prepared. It was found that the morphology of the PEG‐b‐PVFC diblock copolymer nano‐assemblies was dependent on the DP of the PEG and PVFC blocks, and nanospheres favorably formed in the case of the long PEG block and vesicles containing a thick and porous membrane were formed in the case of the short PEG block and long PVFC block, respectively. Our results demonstrate that the dispersion RAFT polymerization is an effective way to prepare the high molecular weight ferrocene‐containing block copolymer with interesting morphologies. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 900–909     

Template‐free anion‐controlled synthesis of Pd (II) nano‐aggregates for the antifouling polymerization of CO and ethylene

The reaction of [(domppp) Pd (OAc)₂] [domppp = 1,3‐bis (di‐o‐methoxyphenylphosphino)propane] and imidazolium‐functionalized carboxylic acids containing various anions (Br^?, PF₆^?, SbF₆^? and BF₄^?) resulted in the formation of nano‐sized Pd (II) aggregates under template‐free conditions. The rate of formation of aggregates can be modulated by changing the anion, affecting the rate of polymerization of CO and olefins without fouling. Herein, we describe the analysis of Pd (II) catalysts by dynamic light scattering, atomic force microscopy, X‐ray photoelectron spectroscopy and X‐ray crystallography, and co‐ and terpolymerization results including the catalytic activity, and bulk density and molecular weight of polymers.     

Synthesis and molecular structure analysis of nano‐sized methacryl‐grafted polysiloxane resin for fabrication of nano hybrid materials

The molecular structures of methacryl‐grafted polysiloxane resins from 3‐(trimethoxysilyl)propyl methacrylate (MPTS) and diphenylsilanediol (DPSD) were determined by theoretical computation and experimental measurement. The molecular structures obtained from theoretical computation coincided well with those from experimental measurement, and we found that the structural changes in the resins could be controlled by precursor compositions. While molecular weights and polysiloxane chain lengths of the resins increase with DPSD contents, their molecular sizes do not vary significantly. In the present study, molecular sizes and shapes of the resins with various compositions are hypothesized theoretically and proven experimentally. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 827–836, 2005