结合表面引发的原子转移自由基聚合和气/固反应制备CdS纳米微粒/聚苯乙烯核壳微球

结合表面引发的原子转移自由基聚合和气/固反应制备CdS纳米微粒/聚苯乙烯核壳微球. 以表面富含环氧基团的聚苯乙烯微球为基底, 利用开环反应在水相中一步接枝表面引发剂, 然后在聚苯乙烯微球表面引发甲基丙烯酸镉的原子转移自由基聚合, 最后通入H2S气体原位生成CdS纳米微粒. 生成的CdS纳米微粒复合的核壳微球呈草莓状形貌, 且具有良好的光学性能.     

Thermosensitive copolymer networks modify gold nanoparticles for nanocomposite entrapment

The core-shell gold nanoparticles and copolymer of N-isopropylacrylamide (NIPAM) and N,N'-methylenebisacrylamide (MBAA) hybrids (Au@copolymer) were fabricated through surface-initiated atom-transfer radical polymerization (ATRP) on the surface of gold nanoparticles in 2-propanol/water mixed solvents. The surface of citrate-stabilized gold nanoparticles was first modified by a disulfide initiator for ATRP. The slight cross-linking polymerization between NIPAM and MBAA occurred on the gold surface and resulted in the formation of core-shell Au@copolymer nanostructures that were characterized by TEM, and FTIR and UV-visible spectroscopy. Such synthesized Au@copolymer hybrids possess clearly thermosensitive properties and exhibit "inspire" and "expire" water behavior in response to temperature changes in aqueous solution. Because of this property, we enable to trap and encapsulate smaller nanoparticles by using the free space of the copolymer-network scaffold anchored at the gold surface.     

Synthesis of Silica@α-Fe2O3 nanospheres by surface-initiated ATRP

We reported a new method to prepare Silica@α-Fe₂O₃ nanospheres by surface-initiated atom transfer radical polymerization (ATRP). Firstly, polymerizable surfactants-modified α-Fe₂O₃ nanoparticles were prepared in water-toluene microemulsion. Then, as-synthesized α-Fe₂O₃ nanoparticles acted as the macro-monomer of surface-initiated ATRP on silica nanospheres to make target product. Morphological characterization of the product was performed using transmission electron microscopy (TEM). Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance UV-vis spectroscopy were used to verify the incorporation of α-Fe₂O₃ nanoparticles on silica nanosphere.     

One-pot synthesis of robust core/shell gold nanoparticles

A one-pot synthesis of thermally stable core/shell gold nanoparticles (Au-NPs) was developed via surface-initiated atom transfer radical polymerization (ATRP) of n-butyl acrylate (BA) and a dimethacrylate-based cross-linker. The higher reactivity of the cross-linker enabled the formation of a thin cross-linked polymer shell around the surface of the Au-NP before the growth of linear polymer chains from the shell. The cross-linked polymer shell served as a robust protective layer, prevented the dissociation of linear polymer brushes from the surfaces of Au-NPs, and provided the Au-NPs excellent thermal stability at elevated temperature (e.g., 110 degrees C for 24 h). This synthetic method could be easily expanded for preparation of other types of inorganic/polymer nanocomposites with significantly improved stability.     

表面引发原子转移自由基聚合方法合成Fe3O4/PMMA复合纳米微粒

采用表面引发原子转移自由基聚合方法合成了核壳结构的磁性高分子纳米微粒. 作为聚合反应引发剂的3-氯丙酸, 首先与油酸修饰的Fe3O4纳米微粒表面的部分油酸置换, 然后在Fe3O4纳米微粒表面引发甲基丙烯酸甲酯聚合, 合成的纳米复合材料用TEM, FTIR, XRD和DSC表征. 磁性测试结果表明, 所制备的磁性高分子纳米微粒仍具有超顺磁性, 但由于聚合物的存在, 其饱和磁化强度降低.     

Thermoresponsive polymer brush on monolithic-silica-rod for the high-speed separation of bioactive compounds

Poly(N-isopropylacrylamide), one of the most utilized thermoresponsive polymers, brush-grafted monolithic-silica columns were prepared through surface-initiated atom transfer radical polymerization (ATRP) for effective thermoresponsive-chromatography matrices. ATRP initiator was grafted on monolithic silica-rod surfaces by flowing a toluene solution containing ATRP initiator into monolithic silica-rod columns. N-Isopropylacrylamide (IPAAm) monomer and CuCl/CuCl(2)/Me(6)TREN, an ATRP catalytic system, were dissolved in 2-propanol, and the reaction solution was pumped into the preprepared initiator-modified columns at 25 °C for 16 h. The constructed PIPAAm-brush structure on the monolithic silica-rod surface was confirmed by XPS, elemental analysis, SEM observation, and GPC measurement of grafted PIPAAm. The prepared monolithic silica-rod columns were also characterized by chromatographic analysis. PIPAAm-brush-modified monolithic silica-rod columns were able to separate hydrophobic steroids with a short analysis time (10 min), compared to PIPAAm-brush-modified silica-beads-packed columns, because of the horizontally limited diffusion path length of monolithic supporting materials. Additionally, diluted PIPAAm-brush monolithic silica-rod column gave a further shorting analysis time (5 min). These results indicated (1) surface-initiated ATRP constructed PIPAAm-brush structures on monolithic silica-rod surfaces and (2) PIPAAm-brush grafted monolithic silica-rod column prepared by ATRP was a promising tool for analyzing hydrophobic-bioactive compounds with a short analysis time.     

Surface initiated ATRP in the synthesis of iron oxide/polystyrene core/shell nanoparticles

A method to prepare magnetic nanoparticles with a covalently bonded polystyrene shell by surface initiated atom transfer radical polymerization (ATRP) was reported. First, the initiator for ATRP was covalently bonded onto the surface of magnetic nanoparticles through our novel method, which was the combination of ligand exchange reaction and condensation of triethoxysilane having an ATRP initiating site, 2-bromo-2-methyl-N-(3-(triethoxysilyl)propyl) propanamide. Then the surface initiated ATRP of styrene mediated by a copper complex was carried out and exhibited the characteristics of a controlled/“living” polymerization. The as-synthesized nanoparticles were coated with well-defined PS of a target molecular weight up to 45 K. These hybrid nanoparticles had an exceptionally good dispersibility in organic solvents and were subjected to detailed characterization using DLS, GPC, FTIR, XPS, UV-vis, TEM and TGA.     

Thermo-responsive polymer brushes as intelligent biointerfaces: preparation via ATRP and characterization

PIPAAm-brush grafted glass substrates with various graft densities and chain lengths were prepared via surface-initiated ATRP. Temperature-dependent physicochemical properties of the surfaces were characterized by means of ATR/FT-IR spectroscopy, XPS, AFM, and contact angle measurements. ATRP conditions influence the amount of grafted PIPAAm and the surface wettability and roughness of the substrate. Fibronectin adsorption and EC adhesion increased with decreasing density of PIPAAm brushes. EC adhesion was diminished with increasing PIPAAm graft length. Thus, the preparation of PIPAAm brush surface with various graft densities and chain lengths using the surface-initiated ATRP is an effective method for modulating thermo-responsive properties of surfaces.     

以聚合物乳胶为模板经表面引发原子转移自由基聚合制备空心二氧化硅纳米微球

均匀的空心纳米及微米球因具有可裁剪结构及良好的光学性能和表面性能,而具有非常广泛的应用前景,空心胶囊是一类重要的材料,它是通过不同的化学和物理方法,直接除去壳-核粒子的内核而获得的,目前主要是通过控制表面沉积。或利用静电相互作用层层组装。制备空心胶囊,但前者易于产生独立的无机粒子沉淀,后者的步骤太过繁琐。     

Thermosensitive water-dispersible hairy particle-supported pd nanoparticles for catalysis of hydrogenation in an aqueous/organic biphasic system

We report in this article the use of thermosensitive water-dispersible polymer brush-grafted polymeric particles as carriers for Pd nanoparticles for the catalysis of hydrogenation of styrene in an aqueous/organic biphasic system. Thermoresponsive poly(methoxytri(ethylene glycol) methacrylate) brushes were grown from initiator-functionalized core-shell cross-linked poly( t-butyl acrylate) (P tBA) particles via surface-initiated atom-transfer radical polymerization. The t-butyl group of P tBA in the core was removed with trifluoroacetic acid, followed by loading of Pd2+ cations through ion exchange. Pd nanoparticles were prepared by reduction of Pd2+ ions with ethanol at 70 degrees C. Dynamic light scattering studies showed that the Pd nanoparticle-loaded thermosensitive hairy particles in water began to shrink when the temperature was above 30 degrees C. The supported Pd nanoparticles efficiently catalyzed hydrogenation of styrene in an aqueous/octane biphasic system and were reused five times with no changes in the yields in the first three cycles and slight decreases in the fourth and fifth cycles after the same period of time. Kinetics studies showed that the catalytic activity of Pd nanoparticles was modulated by the phase transition of the thermosensitive brush layer, resulting in a non-Arrhenius dependence of apparent initial rate constant, k app, on temperature.     

Construction of a comb-like glycosylated membrane surface by a combination of UV-induced graft polymerization and surface-initiated ATRP

Carbohydrate residues are found on the extracellular side of the cell membrane. They form a protective coating on the outer surface of the cell and are involved in intercellular recognition. Synthetic carbohydrate-based polymers, so-called glycopolymers, are emerging as important well-defined tools for investigating carbohydrate-based biological processes and for simulating various functions of carbohydrates. In this work, the surface of a polypropylene microporous membrane (PPMM) was modified with comb-like glycopolymer brushes by a combination of UV-induced graft polymerization and surface-initiated atom-transfer radical polymerization (ATRP). 2-Hydroxyethyl methacrylate (HEMA) was first grafted to the PPMM surface under UV irradiation in the presence of benzophenone and ferric chloride. ATRP initiator was then coupled to the hydroxyl groups of poly(HEMA) brushes. Surface-initiated ATRP of a glycomonomer, D-gluconamidoethyl methacrylate, was followed at ambient temperature in aqueous solvent. Water had a significant acceleration effect on the ATRP process; however, loss of control over the polymerization process was also observed. The addition of CuBr2 to the ATRP system largely increased the controllability at the cost of the polymerization rate. The grafting of HEMA, the coupling of ATRP initiator to the hydroxyl groups, and the surface-initiated ATRP were confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.     

Multifunctional nanoparticles/silica microsphere assemblies using polyglycidyl methacrylate shells as supports

A general method to prepare functional (or multifunctional) nanoparticles/silica microsphere assemblies is reported in this article. A thin shell of polyglycidyl methacrylate is grafted on the surface of silica through surface-initiated atom transfer radical polymerization technique. And then, various types of nanoparticles, including water-soluble CdTe quantum dots, Au nanoparticles and oil-soluble Fe₃O₄ nanoparticles are assembled on silica microspheres, respectively, or simultaneously. The properties of the assembled nanoparticles are well retained in the nanocomposite assemblies, and the controllable integration of magnetic and fluorescent properties can be achieved through varying the proportion of different nanoparticles assembled on nanoparticle/silica microsphere.     

HYDROPHILIC MODIFICATION OF PPESK POROUS MEMBRANES VIA AQUEOUS SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

Hydrophilic surface modification of poly(phthalazinone ether sulfone ketone)(PPESK) porous membranes was achieved via surface-initiated atom transfer radical polymerization(ATRP) in aqueous medium.Prior to ATRP.chloromethyl groups were introduced onto PPESK main chains by chloromethylation.Chloromethvlated PPESK(CMPPESK) was fabricated into porous membrane through phase inversion technique.Hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate)(P(PEGMA)) brushes were grafted from CMPPESK membra...     

A controlled approach to iron oxide nanoparticles functionalization for magnetic polymer brushes

In this article, we report a detailed study of surface modification of magnetite nanoparticles by means of three different grafting agents, functional for the preparation of magnetic polymer brushes. 3-Aminopropyltriethoxysilane (APTES), 3-chloropropyltriethoxysilane (CPTES), and 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane (CTCS) were chosen as grafting models through which a wide range of polymer brushes can be obtained. By means of accurate thermogravimetric analysis a good control over the amount of immobilized molecules is achieved, and optimal operating conditions for each grafting agent are consequently determined. Graft densities ranging from approximately 4 to 7 molecules per nm(2) are obtained, depending on the conditions used. In addition, the surface-initiated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) carried out with CTCS-coated nanoparticles is presented as an example of polymer brushes, leading to a well-defined and dense polymeric coating of around 0.6 PMMA chains per nm(2).     

Functionalization of nylon membranes via surface-initiated atom-transfer radical polymerization

The ability to manipulate and control the surface properties of nylons is of crucial importance to their widespread applications. In this work, surface-initiated atom-transfer radical polymerization (ATRP) is employed to tailor the functionality of the nylon membrane and pore surfaces in a well-controlled manner. A simple two-step method, involving the activation of surface amide groups with formaldehyde and the reaction of the resulting N-methylol polyamide with 2-bromoisobutyryl bromide, was first developed for the covalent immobilization of ATRP initiators on the nylon membrane and its pore surfaces. Functional polymer brushes of 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol)monomethacrylate (PEGMA) were prepared via surface-initiated ATRP from the nylon membranes. A kinetics study revealed that the chain growth from the membranes was consistent with a "controlled" process. The dormant chain ends of the grafted HEMA polymer (P(HEMA)) and PEGMA polymer (P(PEGMA)) on the nylon membranes could be reactivated for the consecutive surface-initiated ATRP to produce the corresponding nylon membranes functionalized by P(HEMA)-b-P(PEGMA) and P(PEGMA)-b-P(HEMA) diblock copolymer brushes. In addition, membranes with grafted P(HEMA) and P(PEGMA) brushes exhibited good resistance to protein adsorption and fouling under continuous-flow conditions.     

NARROW-DISPERSED CROSSLINKED CORE-SHELL POLYMER MICROSPHERES PREPARED BY SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION＊

Grafting of polystyrene with narrowly dispersed polymer microspheres through surface-initiated atom transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) microspheres were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as stabilizer. The surfaces of PDVB microspheres were chloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzene initiating core sites for subsequent ATRP grafting of styrene using CuCl/bpy as catalytic system. Polystyrene was found to be grafted not only from the particle surfaces but also from within a thin shell layer, resulting in the formation of particles size increased from 2.38-2.58μm, which can further grow to 2.93μm during secondary grafting polymerization of styrene. This demonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature. All of the prepared microspheres have narrow particle size distribution with coefficient of variation around 10%.     

Influence of graft interface polarity on hydration/dehydration of grafted thermoresponsive polymer brushes and steroid separation using all-aqueous chromatography

We have prepared poly( N-isopropylacrylamide) (PIPAAm) brush-grafted surfaces with varied temperature-responsive hydrophobic properties through surface-initiated atom transfer radical polymerization (ATRP). These temperature-responsive surfaces were characterized by chromatographic analysis using modified silica beads as a chromatographic stationary phase in aqueous mobile phase. Mixed silane self-assembled monolayers (SAMs) comprising ATRP initiator and silanes with various terminal functional groups were formed on the silica bead surfaces. IPAAm was then polymerized by ATRP using the CuCl/CuCl2/Me6TREN catalyst system in 2-propanol at 25 degrees C for 16 h. The chromatographic retention behavior of steroids on the resulting PIPAAm brushes made on more polar silane components was distinct from that on more apolar silane interfaces. Retention times for steroids on PIPAAm mixed apolar silane graft interfaces were significantly longer than those on analogous polar silane interfaces due to enhanced dehydration of PIPAAm brushes on apolar silane-grafted surfaces. Changes in retention factor, k', on polar silane PIPAAm-grafted interfaces were relatively large compared to that on apolar PIPAAm grafted interfaces due to larger hydration/dehydration alterations of grafted PIPAAm brushes on the former surfaces. Applied step-temperature gradients from 50 to 10 degrees C show that PIPAAm brushes on polar silane interfaces tend to hydrate more, leading to shorter retention times. In conclusion, the polarity of the grafted interface significantly influences the grafted PIPAAm brush hydration/dehydration characteristics and subsequently also the temperature-modulated separation of bioactive compounds in all-aqueous chromatography.     

Synthesis of Hydrophobic Polymer Brushes on Silica Nanoparticles Via the Combination of Surface-Initiated ATRP,ROP and Click Chemistry

A fascinating nanoobject, hydrophobic polymer brushes with a hard core of silica nanoparticles and a relatively soft shell of polystyrene-block-poly(? -caprolactone) (PS-b-PCL), was easily constructed by surface-initiated atom transfer radical polymerization (ATRP) of styrene, ring-opening polymerization (ROP) of ?-caprolactone and click reaction. The structure and morphology of the as-prepared hybrid nanomaterials were characterized and confirmed by FTIR, ¹H-NMR, TGA and TEM. We believe that the breakthrough associated with formation of such a complex nanoobject would open a door for the fabrication of novel functional nanomaterials or nanodevices with designable structure and tailor-made properties.     

Fuzzy ternary particle systems by surface-initiated atom transfer radical polymerization from layer-by-layer colloidal core-shell macroinitiator particles

We report the synthesis of ternary polymer particle material systems composed of (a) a spherical colloidal particle core, coated with (b) a polyelectrolyte intermediate shell, and followed by (c) a grafted polymer brush prepared by surface-initiated polymerization as the outer shell. The layer-by-layer (LbL) deposition process was utilized to create a functional intermediate shell of poly(diallyl-dimethylammonium chloride)/poly(acrylic acid) multilayers on the colloid template with the final layer containing an atom transfer radical polymerization (ATRP) macroinitiator polyelectrolyte. The intermediate core-shell architecture was analyzed with FT-IR, electrophoretic mobililty (zeta-potential) measurements, atomic force microscopy, and transmission electron microscopy (TEM) techniques. The particles were then utilized as macroinitiators for the surface-initiated ATRP grafting process for poly(methyl methacrylate) polymer brush. The polymer grafting was confirmed with thermo gravimetric analysis, FT-IR, and TEM. The polymer brush formed the outermost shell for a ternary colloidal particle system. By combining the LbL and surface-initiated ATRP methods to produce controllable multidomain core-shell architectures, interesting functional properties should be obtainable based on independent polyelectrolyte and polymer brush behavior.     

由平面合成聚合物刷--表面引发原子转移自由基聚合研究进展

原子转移自由基聚合反应(ATRP)是实现活性聚合,获得可控聚合物的一种有效途径。通过表面引发原子转移自由基聚合,在材料表面合成聚合物刷,是改变材料表面特征的有效方法。本文综述了表面引发原子转移自由基聚合合成聚合物刷及其最新进展。