Study on interaction between Eu(III) and thermosensitive microsphere

Based on the synthesis of poly(N-isopropylacrylamide)-grafted poly(N-isopropylacrylamide-co-styrene) (PNNS) microsphere, Eu(III) was chosen to coordinate with PNNS. The interaction between Eu(III) and PNNS was characterized by using X-ray photoelectron spectroscopy, Fourier transform infrared, ultraviolet–visual and fluorescence spectroscopy. The results from experiments indicated that the Eu(III) is mainly bonded to O of the carbonyl groups of PNNS and formed the complex of PNNS–Eu(III). After forming the PNNS–Eu(III) complex, the emission fluorescence intensity of Eu(III) in the complex is significantly enhanced because the effective intramolecular energy-transfer from PNNS to Eu(III). Especially, the maximum emission intensity of the PNNS–Eu(III) complex at 614 nm is enhanced about 33 times comparing to that of the pure Eu(III). The intramolecular energy-transfer efficiency from PNNS to Eu(III) reaches 55%.     

Effect of SiC on the corrosion resistance of electroless Cu–P–SiC composite coating

In this work, Cu–P–SiC composite coatings were deposited via electroless plating with the addition of sodium hypophoshite (NaH₂PO₂) as a reducing agent. The coating compositions deposited were determined by using energy dispersive X-ray spectroscopy (EDX). The surface morphology of the coatings that were analyzed using scanning electron microscopy (SEM) showed that SiC particles were uniformly distributed by virtue of surfactant addition and mechanical stirring. The anti-corrosion properties of Cu–P and Cu–P–SiC coatings in NaCl and HCl solutions were investigated by the weight loss and potentiodynamic polarization techniques. The results showed that the corrosion resistance of Cu–P–SiC coatings was superior to that of electroless Cu–P coatings and carbon steel substrates in various concentrations of NaCl and HCl solutions.     

Synthesis,characterization and thermal behaviors of polymers containing organosilicon groups

Various bis(silyl)ethenyl groups were attached to the aromatic ring of poly(α-methylstyrene) via Peterson olefination reaction of (RMe₂Si)₃CLi (R = H, Me and Ph) with formylated poly(α-methylstyrene) (Pα-MS-CHO) to give poly(α-methylstyrene)-co-[2,2-bis(silyl)ethenyl(α-methylstyrene)] as functionalized poly(α-methylstyrene) (Pα-MS-SiMe₂H, Pα-MS-SiMe₃ and Pα-MS-SiMe₂Ph). The trimethylsilyl groups of Pα-MS-SiMe₃ have been converted to 2,2-dibromoethenyl and epoxybis(silanes) groups via NBS-based bromodesilylation and MCPBA-based epoxidation respectively. The thermal degradation behaviors of the polymers were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).     

The selective oxidation of η‐butane to maleic anhydride: comparison of bulk and supported V–P–O catalysts

V–P–O catalysts supported on the surface of silica and titania particles were studied and compared with bulk V–P–O. The catalytic performance was tested in the η‐butane oxidation reaction to maleic anhydride, and the structure of the equilibrated catalysts was characterised with X‐ray absorption spectroscopy (EXAFS) and (low‐temperature) ESR spectroscopy. Our results show considerable differences in catalytic performance between VPO/TiO₂ on the one hand, and VPO/SiO₂ and VPO/bulk on the other hand, the yield to maleic anhydride being comparable for VPO/bulk and VPO/SiO₂. The differences in catalytic behaviour are attributed to differences in the local structure around vanadium (EXAFS). Furthermore, different spin exchange interactions between vanadium atoms in the three samples have been observed (ESR). The combination of characterisation methods suggests that the structure of the supported V–P–O phase is amorphous and differs considerably from that of bulk crystalline vanadylpyrophosphate. We therefore propose that the oxidation of η‐butane to maleic anhydride takes place over an amorphous surface V–P–O phase. This finding has high relevance for our understanding of the catalytic activity of bulk crystalline V–P–O catalysts as well. This revised version was published online in July 2006 with corrections to the Cover Date.     

A facile route for the preparation of novel optically active poly(amide–imide)/functionalized zinc oxide nanocomposites containing pyromellitoyl-bis-l-phenylalanine moieties

In the present investigation, at first, the surface of zinc oxide (ZnO) nanoparticles was treated with a silane coupling agent of γ-methacryloxypropyltrimethoxy silane (KH570), which introduces organic functional groups on the surface of ZnO nanoparticles. Secondly, optically active poly(amide–imide) (PAI) was synthesized via solution polycondensation of N,N′-(pyromellitoyl)-bis-phenylalanine diacid chloride 1 (M-1) with 4,4′-diaminodiphenylsulfone 2 (M-2). The polycondensation of diacid chloride with aromatic diamine was carried out with N,N-dimethylacetamide/triethylamine systems. Finally PAI/ZnO nanocomposites (NCs) containing 4, 8, and 12% of nanoparticles were successfully fabricated through ultrasonic irradiation technique. The obtained NCs were characterized by Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetry analysis, X-ray powder diffraction, UV–Vis spectroscopy, scanning electron microscopy (SEM), field emission-scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The FT-IR spectroscopy indicated that the silane coupling agent was anchored on the surface of ZnO nanoparticles. SEM, FE-SEM, and TEM images were showed ZnO nanoparticles were dispersed homogeneously in PAI matrix.     

Surface properties and chain structure of fluorinated acrylate copolymers prepared by emulsion polymerization

The fluorinated copolymer poly (MMA–co–FMA), composed of methyl methacrylate (MMA) and 2-perfluorooctylethyl methacrylate (FMA), was prepared by emulsion polymerization using a pre-emulsified monomer addition process. The results showed that the contact angle of water on its solvent-borne film increased dramatically and reached 118o when the FMA content in the copolymer was only 0.65 mol%, approaching that of poly(2-perfluorooctylethyl methacrylate) homopolymer. Unlike the copolymer prepared by solution polymerization, X-ray photoelectron spectroscopy (XPS), and sum frequency generation (SFG) vibrational spectroscopy analysis results indicated that the fluorinated moieties in this polymer were very easily segregated at the surface of the film. The interfacial structure and properties of this polymer in solution were investigated using SFG, surface tension, and dynamic laser light scattering (DLS). It was found that emulsion polymerization produced a chain structure of the fluorinated copolymer similar to that of FMA capped PMMA, thereby providing a possible way to produce fluorinated end-capped polymers using a popular polymerization method.     

Surface analysis of PP/EVA blends modified with amino acids for biomedical applications

The copolymers poly(propylene-co-ethylene) (PP/E) and poly(ethylene-co-vinyl acetate) (EVA) and blends of these were modified to develop an artificial matrix which promotes the growth of endothelial cells. Covalent immobilization of amino acids or sequences of adhesion glycoproteins should trigger the formation of an endothelial cell monolayer onto the polymeric surface. Reactive functional groups were generated by saponifying the ester groups of the EVA component. Esterification with oxalylic or malonic dichlorides in the gas phase yielded the required monoesters and gave the best results for further immobilization of amino acids, while reaction with α,ω-dicarboxylic acid dichlorides in solution led to diester formation. Subsequently, various protected amino acids were immobilized via the carbodiimide method. Surface analytical methods like infrared spectroscopy using at tenuated total reflection (IR-ATR), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS) were used to prove the modification steps. The analytical results confirmed covalent side-chain generation in the upper surface region. © 1995 John Wiley & Sons, Inc.     

NanoZnO initiated polymerization of N-vinylcarbazole (NVC) and evaluation of a poly(N-vinylcarbazole)–ZnO nanocomposite

The polymerization of N-vinylcarbazole was conducted in bulk in presence of ZnO without any external initiator and a nanocomposite of poly(N-vinylcarbazole)–ZnO (PNVC–ZnO) was isolated from the system. The polymerization of N-vinylcarbazole by ZnO impregnated with acetylene black (AB) and Fe³⁺ was also conducted to isolate the respective AB and Fe³⁺ loaded PNVC–ZnO composites, PNVC–ZnO(AB) and PNVC–ZnO(Fe³⁺). The formation of the poly(N-vinylcarbazole) in these systems was confirmed by FTIR, UV–vis and emission spectroscopic analysis. TGA, DSC and SEM characteristics of these composites were evaluated in details. XRD analysis revealed no crystanillity in poly(N-vinylcarbazole) moiety. PNVC–ZnO was nonconducting but PNVC–ZnO(AB) and PNVC–ZnO(Fe³⁺) systems exhibited conductivities in the range 0.12 and 10⁻³ S/cm respectively. A carbocationic propagation pathway was suggested to explain the initiation of N-vinylcarbazole by Zn⁺⁺ moiety in ZnO. Kinetic studies revealed that the polymerization is first order with respect to ZnO and the monomer concentration respectively.     

Synthesis,characterization, and infrared-emissivity study of Ni–P–CB nanocomposite coatings by electroless process

The Ni–P–CB (carbon black) nanocomposite coatings have been successfully deposited on an ABS plastic matrix via electroless plating process. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectrometry techniques were employed to examine the surface morphology and structure of the as-plated coating. Energy dispersive spectroscopy (EDS) was adopted to obtain the component analysis of the Ni–P–CB composite coating, and the infrared emissivity of the coating was determined by the IRE-I Infrared Emissometer. SEM and XRD results indicated that the nanoparticles were dispersed homogeneously in the Ni–P coating; the result of EDS showed that the increased rate of CB content is in correspondence with its concentration. In the case that CB concentration is lower than 4 g/L, the increase rate is sharp, whereas when the concentration is higher than 4 g/L, the increase rate is reduced significantly. Furthermore, study of infrared emissivity shows that the nanocomposite coatings possessed low emissivity value. A comparison of the infrared emissivity dependence on surface resistivity obtained from the analysis of the experimental results and those calculated using the Hagen–Rubens relation indicates that the Hagen–Rubens relation is good for modeling the infrared emissivity of the Ni–P–CB nanocomposite coatings.     

The preparation and characteristics of poly(methyl methacrylate–methylacrylate acid)/nano-ZnO composite latex particles

In this work, poly(methyl methacrylate-co-methylacrylate acid)/ZnO (poly(MMA–MAA)/ZnO) composite latex particle was synthesized by three steps The first step was to synthesize poly(MMA–MAA) copolymer latex particles by soapless emulsion polymerization. Following the first step, the second step was to polymerize MMA, MAA and 3,3-(trimethoxysilyl) propyl methacrylate (MPS) in the presence of poly(MMA–MAA) seed latex particles to form the poly(MMA–MAA)/poly(MMA–MAA–MPS) core–shell latex particles. In the third step, the poly(MMA–MAA)/poly(MMA–MAA–MPS) latex particles reacted with ZnO nanoparticles, which were synthesized by a traditional sol gel method, to form the polymer/inorganic poly(MMA–MAA)/poly(MMA–MAA–MPS)/ZnO composite latex. In this study, MPS with silanol groups essentially was used as the coupling agent to couple with ZnO nanoparticles, while the results of the study showed that there was not covalent bond existed between ZnO particles and polymer latex. The ZnO particles were adsorbed on the surface of polymer latex by electrostatic interaction. Besides, the linear poly(MMA–MAA)/crosslinking poly(MMA–MAA–MPS) core–shell latex particles which were synthesized in the second step were heated in the presence of ammonia to form the hollow poly(MMA–MAA–MPS) latex particles. The factors of heating time and concentration of crosslinking agent significantly influenced the morphology of hollow poly(MMA–MAA–MPS) latex particles.     

Enhanced mechanical and photoluminescence effect of poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide) reinforced with functionalized multiwalled carbon nanotubes

The poly(l-lactide) (PLLA) biocompatible and biodegradable polymer was reinforced with functionalized Multiwalled carbon nanotubes (MWCNTs) to overcome on insufficient mechanical properties of this polymer for high load bearing applications. To fully realize the potential of MWCNTs for this purpose, they have to be homogeneously dispersed in polymer matrix and have efficient load transfer across the MWCNTs/polymer interface. The pristine MWCNTs (pMWCNTs) were functionalized, at first, by Friedel–Crafts acylation, which introduced the aromatic amine groups on the sidewall of MWCNTs (MWCNT–NH₂) without shortening or cutting of pMWCNTs. And then, the PLLA chains covalently grafted from the sidewall of MWCNT–NH₂ by in situ ring-opening polymerization of l-lactide oligomers using stannous octanoate as the initiating system. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy spectra revealed that the PLLA chains grafted form the sidewall of MWCNTs strongly. The surface morphology of pristine and PLLA-grafted MWCNTs (MWCNT-g-PLLAs) was characterized by scanning electron microscopy and transmission electron microscopy. The tensile test of prepared composites of PLLA with various concentrations of MWCNT-g-PLLAs show a significant increment in tensile strength and elongation at failure of composites with increasing the concentration of MWCNT-g-PLLAs in composites. Also, it is found that the MWCNT-g-PLLAs increased the photoluminescence effect of PLLA and widened the luminescence region of PLLA.     

Patterning Si by using surface functionalization and microcontact printing with a polymeric ink

This paper describes a simple procedure for patterning Si substrate using a combination of surface functionalization and microcontact printing(ΜCP). The Si/SiO₂ surfaces were chemically modified to present self-assembled monolayers (SAMs) of siloxanes terminating in reactive carboxylic anhydride groups and then patterned with poly(ethylene imine) (PEI) by, ΜCP We used the patterned thin films of PEI as etch resists on Si surfaces.     

Graft copolymerization of N-isopropylacrylamide with 3-(methacryloxy)propyl trimethoxysilane on ultrafine silica and its application in chromatography separation

Thermosensitive core-shell particles were synthesized through graft copolymerization of N-isopropylacrylamide with [ 3-(methacryloxy) propyl]trimethoxysilane (MPT) coupled on the surface of ultrafine silica beads. The copolymerization was carried out using polyvinyl alcohol as a surfactant, water and cyclohexanol as mixed solvent, and 2,2′-azobis(isobutyronitrile) as an initiator. The effect of surfactant concentration and the composition of the mixed solvent on the graft rate were investigated. The structure of modified silica was confirmed by infrared spectra. Differential scanning calorimetry (DSC) has revealed the thermosensitivity of the particles. The thermosensitive particles were used as packing materials of high performance liquid chromatography (HPLC) columns for separating naphthalene derivatives. Satisfactory separation was obtained by controlling the temperature of the column. In contrast, the packing material of silica-MPT has no such separation efficiency due to the lack of thermosensitivity. The effect of the composition of the mobile phase on the separating efficiency was also investigated. The temperature-controlled separation was effective only when the water content was higher than 90% (v/v) in the water-methanol mobile phase. The mechanism for the temperature-controlled separation is attributed to a polarity change of poly(N-isopropylacrylamide) which undergoes volume phase transition on the silica surface as the temperature increases. __________ Translated from Acta Polymerica Sinica, 2007, 8(8): 765–769 [译自: 高分子学报]     

CMC and dynamic properties of poly(VA-<Emphasis Type="Italic">b</Emphasis>-St) copolymer micelles for drug delivery

The polymeric micelles from amphiphilic block copolymer poly(vinyl alcohol-b-styrene) (poly(VA-b-St)) with different syndiotacticity of poly(vinyl alcohol) (PVA) block were prepared by dialysis against water. Critical micelle concentration (CMC) and dynamic properties of poly(VA-b-St) copolymeric micelles were investigated by fluorescence techniques. From the fluorescence emission spectrum measurements using pyrene as a fluorescence probe, the observed CMC value was in the range of 0.125–4.47 mg/L. The CMC value increased with decreasing the weight ratio of PS to PVA block and with increasing the syndiotacticity of PVA block. The rate of pyrene release was very slow for block copolymers containing PVA block with higher syndiotacticity, which indicates that their micelles have increased kinetic stability. This work was presented at 13 ^th YABEC symposium held at Seoul, Korea, October 20–22, 2007.     

Swelling characterization of poly (acrylamide-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">N</Emphasis>-vinylimidazole) hydrogels crosslinked by TMPTA and semi-IPN’s with PEG

In this study, a novel semi-interpenetrating network (semi-IPN’s) hydrogel, composed of acrylamide (AAm) with N-vinylimidazole (NVI) as comonomer, with poly (ethylene glycol)(PEG) and a multifunctional crosslinker such as trimethylolpropane triacrylate (TMPTA) was prepared. Highly swollen poly (AAm/NVI) hydrogels and semi-IPN’s were synthesized by free radical solution polymerization. Swelling experiments were performed in water at 25°C, gravimetrically. The influence of NVI and PEG content in hydrogels were examined. Poly (AAm/NVI) and poly (AAm/NVI/PEG) hydrogels showed large extents of swelling in aqueous media the swelling being highly dependent on the chemical composition of the hydrogels. Swelling ratio of poly (AAm/NVI) hydrogels and poly (AAm/NVI/PEG) hydrogels was shown 7.16–39.85. Diffusion behavior was investigated. Water diffusion into hydrogels was found to be non-Fickian in character. This study has given the quantitative information on the swelling characteristic of poly (AAm/NVI) hydrogel and semi-IPN’s as water absorbent in many potential applications.     

Surface grafting polymerization of vinyl monomers on poly(tetrafluoroethylene) films by plasma treatment

Poly(tetrafluoroethylene) films were surface modified by argon plasma treatment followed by graft polymerization. Peroxidе groups were introduced on the surface of poly(tetrafluoroethylene) films after plasma treatment and the consequent contact with air when the films were taken out of the reactor. Grafting polymerization initiated by the surface peroxide (hydroxide) groups was performed on the poly(tetrafluoroethylene) film surface by using acrylic acid, 4-vinylpyridine and 1-vinylimidazole as monomers. Copolymers were obtained with grafting yield from 0.436 to 0.457 mg/cm² for poly(acrylic acid), from 0.299 to 0.390 mg/cm² for poly(4-vinylpyridine) and from 0.212 to 0.256 mg/cm² for poly(1-vinylimidazole), respectively. The free surface energies of the copolymers were determined. The chemical structures and the copolymer surfaces were characterized by IR, XPS and SEM analyses. High energy resolution X-ray photoelectron spectroscopy (XPS) confirmed the grafting of acrylic acid, 4-vinylpyridine and 1-vinylimidazole. The surface hydrophilicities of modified polytetrafluoroethylene films were significantly enhanced after plasma treatment and grafting modification. It is worth emphasizing that in this work acrylic acid, 4-vinylpyridine and 1-vinylimidazole were used as the reactive monomers for grafting on the poly(tetrafluoroethylene) film by plasma treatment. We believe that this vinyl monomers may be employable as functional groups, permitting a potentially wide range of applications: as ionomers, membranes, carriers for immobilization of biomolecules, for complex formation with heavy metals as catalysts.     

Low-temperature selective catalytic reduction of NO with NH3 based on MnOx-CeOx/ACFN

MnO _x -CeO _x /ACFN were prepared by the impregnation method and used as catalyst for selective catalytic reduction of NO with NH3 at 80°C-150°C. The catalyst was characterized by N₂-BET, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The fraction of the mesopore and the oxygen functional groups on the surface of activated carbon fiber (ACF) increased after the treatment with nitric acid, which was favorable to improve the catalytic activities of MnO _x -CeO _x /ACFN. The experimental results show that the conversion of NO is nearly 100% in the range 100°C-150°C under the optimal preparation conditions of MnO _x -CeO _x /ACFN. In addition, the effects of a series of performance parameters, including initial NH₃ concentration, NO concentration and O₂ concentration, on the conversion of NO were studied. __________ Translated from Chemical Industry and Engineering Progress, 2007, 27(1): 87–91 [译自: 化工进展]     

Studies on the radical polymerization of N-vinyl 2-pyrrolidone initiated by diphenyl ditelluride

N-vinyl pyrrolidone (NVP) was polymerized in dioxan at 60 ± 0.1°C for 1 h using diphenyl ditelluride as radical initiator. The system follows ideal kinetics i.e. R _p α [DPDT]^0.5[NVP]. The activation energy and dissociation constant is computed as 46 kJ mol⁻¹ and 1.1 × 10⁻¹¹ s⁻¹, respectively. The polymer was characterized with the help of FTIR, ¹H-NMR, ¹³C-NMR, ESR spectroscopy. The FT-IR spectrum showed bands at 1660–1680 cm⁻¹ due to combination of >C = O and C–N stretching. The gyromagnetic constant ‘g’ has been computed as 2.2203. The main product of this reaction were poly(N-vinylpyrrolidone)s with phenyl tellanyl ends. The presence of tellurium in polymer is confirmed by ICP analysis. The DSC shows the T _g of poly(N-vinylpyrrolidone) is 168°C due to rigid pyrrolidane group. The TGA showed that polymer was stable up to 380°C.The GPC studies showed that the weight average molecular weight decreases with increase of [DPDT].     

Synthesis, formulation, and characterization of siloxane–polyurethane coatings for underwater marine applications using combinatorial high-throughput experimentation

Crosslinked siloxane–polyurethane coatings were designed, synthesized, formulated, applied, and characterized using combinatorial high-throughput experimentation and eight coatings were selected as candidates for further characterization. First, 72 novel hydroxyalkyl carbamate and dihydroxyalkyl carbamate-terminated poly(dimethylsiloxane) (PDMS) oligomers and their carbamate-linked block copolymers with poly(ε-caprolactone) (PCL) were synthesized using a high-throughput synthesis system. These PDMS oligomers and block copolymers were characterized for their molecular weight using high-throughput Gel Permeation Chromatography (Rapid-GPC). The 72 oligomers were then incorporated into siloxane–polyurethane formulations at four different levels resulting in 288 coatings. After initial screening of these 288 coatings, eight coatings were selected for further characterization. Differential scanning calorimetry, dynamic mechanical analysis, X-ray photoelectron spectroscopy and surface energy analysis demonstrate the presence of PDMS on the surface with a polyurethane underlayer. Pseudo-barnacle adhesion and the attachment strength of reattached live barnacles (Balanus amphitrite) were in good agreement. Out of the eight coatings that were down-selected, two coatings performed well in algal (Ulva), bacterial (Cytophaga lytica, Halomonas pacifica), and barnacle (Balanus amphitrite) laboratory screening assays and are potential candidates for ocean testing. This paper was awarded Second Place in the 2006 Roon Awards competition, held as part of the FutureCoat! conference, sponsored by the Federation of Societies for Coatings Technology, in New Orleans, LA, on November 1-3, 2006.     

Poly(Urethane–Urea) Varnishes Containing Tributyltin Groups

New poly(urethane–urea) varnishes containing tributyltin groups were prepared by the reaction of dibenzyldiisocyanate in excess with a macrodiol (PEGA-2000), trimethylolpropane, diethylene glycol and a bisalcohol maleimide monomer containing tributyltin carboxylate group. Tributyltin maleimide monomers were obtained from 4-{3,4-bis[(2-hydroxyethyl)sulfanyl]-2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl}benzoic acid and bis(tributyltin) oxide. Structure of monomers and polymers was confirmed by the IR, NMR spectroscopy and elemental analysis. The polymer films were characterized by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), X-ray diffractions, thermogravimetric (TGA) and stress–strain measurements.