Preparation and Characterization of Polymer‐Protected Pt@Pt/Au Core‐Shell Nanoparticles

Poly(N‐vinyl‐2‐pyrolidone) protected Pt‐core bimetallic Pt/Au‐shell (Pt@Pt/Au) nanoparticles were prepared by multi‐step reduction of HAuCl₄ and H₂PtCl₆ alternately by hydrogen adsorbed on platinum atom. Transmission electronic microscopy (TEM) and x‐ray diffraction (XRD) were used to characterize Pt@Pt/Au nanoparticles. The structure of the shell of the nanoparticles seems to be the Au‐Pt solid solution.     

Preparation of Poly(methyl methacrylate) Nanoparticles 15–50 nm in Diameter from Submicrometer-Sized Latex Particles

Russian Journal of Applied Chemistry - A procedure was developed for preparing poly(methyl methacrylate) nanoparticles of 15–50 nm size from coarser (200–300 nm) polymer latex particles...     

The Preparation and Biodegradable Properties of Poly(L‐lactic acid)‐Poly(ϵ‐caprolactone) Multiblock Copolymers

Multi‐block copolymers of PLLA and PCL were prepared by a coupling reaction between PLLA and PCL prepolymers with –NCO end groups. FTIR proved that the products were PLLA‐PCL copolymers. The weight‐average molecular weight of the copolymers was up to 180,000 at a composition of 60% PLLA and 40% PCL. The degradation properties of PLLA and PLLA‐PCL copolymers were studied by a soil burial test and a hydrolysis test in a phosphate‐buffer solution. The degradation rate was estimated by the mass loss, molecular weight reduction, pH value changes and swelling index; the degradation rates of the copolymers were a function of the composition of PLLA and PCL. Increasing PCL content in the copolymers resulted in lower degradation rate.     

Preparation of Some Derivatives of N‐tert‐Butyldecahydro‐3‐isoquinoline Carboxamide

N‐tert‐Butyldecahydro‐3‐isoquinoline carboxamide (1) is a key structural fragment present in a variety of medicinally important HIV protease inhibitors. Derivatives of this carboxamide were prepared by alkylation with either 2‐iodoethanol, allyl bromide, or bromoacetaldehyde dimethylacetal. The corresponding aldehyde of the dimethylacetal derivative was prepared by reaction with BBr₃ in CH₂Cl₂.     

Preparation and Characterization of Poly(N‐Vinylpyrrolidone‐co‐Methacrylic Acid) Hydrogels

In this study, N‐vinylpyrrolidone (VP)/methacrylic acid (MAA) copolymers have been prepared at three different mole percents, the methacrylic acid composition being around 5, 10, 15%. MAA and VP monomer mixtures have been irradiated in ⁶⁰Co‐γ source at different irradiation doses and percent conversions have been determined gravimetrically. ～80% conversion of monomers into hydrogels were performed at 3.4 kGy irradiation dose. These hydrogels were swollen in distilled water at pH 4.0, 7.0, and 9.0. P(VP/MAA) hydrogel which contains 5% methacrylic acid showed the maximum % swelling at pH 9.0 in water. Diffusion of water was found to be of non‐Fickian character. Diffusion coefficients of water in P(VP/MAA) hydrogels were calculated. Initial swelling rates of P(VP/MAA) hydrogels increased with increasing pH and MAA content in hydrogels. Swelling kinetics of P(VP/MAA) hydrogels was found to be of second order. Thermal behavior of PMAA, PVP and P(VP/MAA) hydrogel were investigated by thermal analysis. P(VP/MAA) hydrogel gained new thermal properties and the temperature for maximum weight loss and temperature for half‐life of P(VP/MAA) hydrogel were determined.     

Preparation of Core/Shell Structure of α-Al(OH)3-SiO2 by Heterogeneous Nucleation-and-Growth Processing

In order to solve the difficult problem of heterogeneity of different components in the procedure of ceramic preparation, a novel processing (heterogeneous nucleation-and-growth processing) was used to prepare homogeneous distribution powders. Composite coating particles consisting of alpha aluminum hydroxide (-Al(OH)₃) cores (average particle size 0.42 m) with outer homogeneous amorphous silica layer are prepared by heterogeneous nucleation-and-growth processing. Effects of silica content in composite coating particles versus concentration of silicon tetraethoxide (TEOS), pH value, time and temperature are studied. The homogeneous amorphous silica layer on cores is confirmed by X-ray diffraction, transmission electron microscopy and zeta potential measurement.     

Synthesis of CuInS2@CdS Core‐Shell Nanocrystals

CuInS₂@CdS core‐shell nanocrystals were prepared in a wet chemical process. Transmission electron microscope (TEM), x‐ray energy dispersive spectroscopy (EDAX), x‐ray diffraction (XRD), absorption, and photoluminescence (PL) spectra were used to confirm the formation of the CuInS₂@CdS core‐shell structure. The growth of CdS shell not only increased the PL intensity, but also restrained the transformation of CuInS₂ from nanoparticles to nanorods after annealing, which was attributed to an effective chemical passivation of the CuInS₂ core by the CdS shell.     

Preparation and Characterization of Titania-grafted Poly（styrene-divinybenzene） Nanocomposite Microspheres

Titania-grafted poly（styrene-divinylbenzene）（TiO2/PSt-DVB） nanocomposite microspheres were prepared by an open-ring reaction and radical grafting copolymerization method. The TiO2 nanoparticles were first modified by attachment of epoxy groups to their surfaces to provide reactive groups that could covalently bond to the polymer （PSt-DVB） microspheres. The nanocomposite obtained was characterized by FTIR, SEM, XRD, and TGA analyses as well as UV-Vis spectrophotometry. The results indicated that the TiO2 nanoparticles were uniformly grafted onto the surface of the polymer microsphere producing grain sizes of about 5―10 μm. The modified TiO2 showed better UV absorbing property than the unmodified form, and the nanocomposite also retained the same UV absorbing property as the free modified TiO2 nanoparticle.     

Preparation of Comb‐like Styrene Grafted Silica Nanoparticles

Abstract

Comb‐like polystyrene grafted silica nanoparticles (c‐PS‐SNs) were prepared by the following steps: (a) methacryloxypropyl silica nanoparticles (MPSNs) were used as macromonomer and free radical copolymerized with 4‐vinyl benzyl chloride (VBC) by a solution polymerization method; (b) the product of (A), poly(4‐vinyl benzyl chloride) grafted silica nanoparticle (PVBC‐SN) was separated and then used as a macroinitiator for the surface‐initiated atom transfer radical polymerization (SI‐ATRP) of styrene catalyzed by the complex of Cu(I)Br and 2,2′‐bipyridyl (bipy) in toluene solutions. The structurally well‐defined polymer chains were grown from the nanoparticle surfaces to yield particles composed of a silica core and a well defined, densely grafted outer comb‐like PS layer. A percentage of grafting (PG%) (the weight ratio of the PS grafted with that of the silica charged) of more than 80% was achieved after a polymerizing time of 5?hr.     

A Way to Prepare Core‐Shell Biocompatible Polymeric Nano‐Particles from Gelatin and Acrylic Acid

Narrowly distributed core‐shell nano‐particles at relatively high concentration (30 mg/mL) were prepared via in situ polymerization of acrylic acid in an aqueous solution of biocompatible gelatin. These polymeric nano‐particles, in aqueous solution, had cores mainly comprised of an insoluble inter‐polymer complex of poly(acrylic acid, PAA) and gelatin and shells comprised of soluble gelatin (denoted as gelatin/PAA nano‐particles). Dynamic light scattering and electrophoretic light scattering techniques were used to trace the in situ polymerization process. The structure of the gelatin/PAA nano‐particle was further locked‐in via shell crosslinking; i.e., the reaction between glutaraldehyde and gelatin. Scanning force microscopy (SFM) was used to observe the morphologies of the particles before and after cross‐linking. Furthermore, the pH responsive behaviors of the gelatin/PAA nano‐particles before and after shell crosslinking were studied.     

Preparation of Silver Nanoshells on Silica Particles by a Simple Two-step Process

A simple two-step method was developed to prepare silver nanoshells coated on silica paticles. The method involves two steps: concentration of reaction precursor (AgNO3) on particle surfaces and subsequent reduction by formaldehyde. The obtained composite particles were characterized by TEM, ED, and SEM-EDS measurements. The results show that the silver nanoshell is coated on silica particle surface in the form of a polycrystalline (cubic structure) layer with average thickness of 20 nm and weight percentage of 1.9%.     

Preparation and Chemical Behavior of 2‐(tert‐Butoxycarbonyl)amino‐3‐bromomethyl Pyridine,a Novel Alkylating Agent

Synthesis of a novel heterocyclic alkylating agent has been developed. Its instability toward elevated temperatures and/or polar media can be used to prepare 8‐aza‐1,4‐dihydrobenzo[1,3‐d]oxazin‐2‐one.     

Synthesis of Poly[2‐decyloxy‐5‐(4′‐tert‐butylphenyl)‐1,4‐phenylenevinylene] as a Light Emitting Material

In this study, a new electroluminescent poly(2‐decyloxy‐5‐(4′‐tert‐butylphenyl)‐1,4‐phenylene‐vinylene) (designated as DBP‐PPV) with no tolane‐bis–benzyl (TBB) structure defect was prepared by dehydrohalogenation of 1,4‐bisbromomethyl‐2‐decyloxy‐5‐(4′‐tert‐butyl‐phenyl) benzene (as monomer). The monomer bearing decyloxy and 4′‐tert‐butylphenyl substituents was synthesized via alkylation, bromination and Suzuki coupling reactions. The two asymmetric substituents of the monomer can suppress the formation of TBB defect during polymerization process and make the resultant polymer be soluble in common organic solvents. The structure and properties of DBP‐PPV were examined by ¹H‐NMR, FT‐IR, UV/Vis, TGA and photoluminescence (PL) analyses. Moreover, with the DBP‐PPV acting as a light‐emitting polymer, a device with sequential lamination of ITO/PEDOT/DBP‐PPV/Ca/Ag was fabricated. The electroluminescence (EL) spectrum of the device showed a maximum emission at around 546 nm, corresponding to a yellowish‐green light. The device showed a turn‐on voltage of about 8.4 V and a maximum luminescence efficiency of 0.11 cd/A at an applied voltage of 12 V.     

Preparation and Application of a Nanocomposite (MPNS/SMA) in Leather Making

Environmental pollution is one of headache problems in leather tanning industry.Traditionally chrome tanning was the predominant technique used in leather making.However,chrome tanning is being substituted due to its pollution and scarcity of resource.The study of non-chrome tanning in leather shows more interests with the development of nanomaterial and nanotechnology.J.Z.Ma et al.have reported that organic–montmorillonite nanocomposite can raise the shrinkage temperature of pickled pigskin…     

Preparation and Chromatographic Features of Fibrous Core–Shell HPLC Packing Material

In this study, fibrous core–shell silica particles were successfully synthesized via a one-step oil–water biphase stratification coating strategy. The core–shell silica particles were composed of 3-µm non-pore silica cores and thin shells (50–100 nm), which have radial-like direct channels and a large pore size (19.89 nm). The fibrous core–shell silica particles were further modified by n-octadecyltrichlorosilane and used as stationary-phase media in high-performance liquid chromatography (HPLC). The chromatographic properties of the particles were systematically studied in small-molecule and protein separation processes. The results showed that the back pressure was as low as 8.5 MPa under the 1.0-mL min^?1 flow velocity. Furthermore, fibrous core–shell silica particles with an 80-nm shell were used for separating seven small molecules within 10 min and six proteins within 6 min. This work demonstrates that the fibrous core–shell silica particles could be used as an HPLC stationary phase with good performance and low back pressure, and that they have great potential for application to HPLC separation in the future.     

Preparation of Macroporous Aluminium Oxide using Template of Poly(methacrylic acid‐co‐glycidylmethacrylate) Crosslinked with Methylenebisacrylamide

Poly(methacrylic acid‐co‐glycidylmethacrylate), poly(MA‐co‐GMA) samples were prepared by exposure to γ–irradiation, at fixed concentration of methylenebisacrylamide MBA, 0.5% wt/wt as crosslinker while the MA/GMA ratio was varied. FTIR spectra showed bands refer to MA, as well as GMA, indicating the involvement of both in the copolymerization. Al(NO₃)₃.9H₂O as a precursor for the preparation of aluminium oxide was templated as a guest into the crosslinked gels by soaking the gels in a methanol solution. The perturbation of the bands at 3439, 2926, 1635, 1476, 1394, and 1166 cm^?1 after the templation of the guest, provides evidence for the loading of the guest species into the gel. The swelling behavior of the prepared samples found to be dependent on the composition of the gel and the pH. The templation of the aluminium nitrate into the gel was further proved by thermal gravimetric analysis (TGA). Scanning electron microscopy (SEM) was used for investigating the produced oxide particles, which revealed macropores with maximum diameter at MA/GMA, 40∶60 wt/wt (H3) and complete disappearance at 80 wt% of methacrylic acid (H5). X‐ray diffraction (XRD) showed an amorphous structure of the aluminium oxide. Increasing the hydrophilicity of the template leads to an increase in the Lewis acidic sites on the surface of the produced aluminium oxide up to 60 wt% of methacrylic acid (H4) while a further increase was met by a redecrease in the surface acidity (H5).     

Electrochemical Properties of Poly (ethyl acrylate-co-lithium methacrylate) Latex Film Solid Electrolyte

Muchattentionhasbeenpaidtothedevelopmentofnewpolymerelectrolytewithspecialmorphology,soastoimprovetheirelectrochemicalpropertiestomeettheneedsoflithium(ion)battery.Inthiswork,PEMlatexwassynthesizedbyemulsion-fi-eepolymerization.ThemicrophotoofPEMlate...     

Preparation of Poly(N‐isopropylacrylamide) Microgels using Different Initiators Under Various pH Values

Ammonium persulfate (APS), 2,2′‐azobis(amidinopropane) dihydrochloride (V50) and 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) were utilized to prepare temperature‐sensitive poly(N‐isopropylacrylamide) (PNIPAM) microgels by precipitation polymerization under various reaction pH conditions. Their particle sizes and swelling ratios depended on the reaction pH due to the pH dependence on the ionization degree of the decomposed fragments originating from the initiators and their hydrophilicity‐hydrophobicity. The more hydrophobic initiator, under the reaction pH conditions used, could be partitioned to a greater extent into the microgel particles due to the hydrophobicity of PNIPAM chains at the reaction temperature, which led to a more cross‐linked structure inside the microgels resulting in their smaller swelling ratio. pH dependence of surface charge density of the microgels with amidino groups or carboxylic acid groups on their surfaces was evidenced by the variation of their zeta potentials as a function of pH.