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1.
Magnetic nanoparticles grafted with poly(poly(ethylene glycol) monomethacrylate) (P(PEGMA)) were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. In this approach, S-benzyl S′-trimethoxysilylpropyltrithiocarbonate, used as a chain transfer agent for RAFT, was first immobilized onto the magnetic nanoparticle surface, and then PEGMA was grafted onto the surface of magnetic nanoparticle via RAFT polymerization. The results showed that P(PEGMA) chains grew from magnetic nanoparticles by surface-induced RAFT polymerization. The grafted P(PEGMA) chains can decrease the nonspecific adsorption of proteins on the surface of Fe3O4 nanoparticles. 相似文献
2.
A simple method was developed for the immobilization of reversible addition-fragmentation chain-transfer (RAFT) initiators on the silicon surface. Well-defined polymer-silicon hybrids, including the tethered brushes of glycidyl methacrylate (GMA) polymer, poly(ethylene glycol) monomethacrylate (PEGMA) polymer and block copolymer on a silicon wafer, were prepared via surface-initiated RAFT living radical polymerization. The “living” chain ends were used as the macroinitiator for the subsequent synthesis of diblock copolymers. 相似文献
3.
Jianhua Qiu Yongbo Shen Yatao Zhang Haoqin Zhang Jindun Liu 《Applied Surface Science》2010,256(10):3274-1097
Polyacrylamide (PAM) brushes were grafted from chloromethylated polysulfone (CMPSF) membrane surface by surface-initiated atom transfer radical polymerization (SI-ATRP) to improve the membrane's hydrophilic property. In order to anchor the initiator onto polysulfone (PSF) membrane surface, CMPSF was used to prepare the microporous membrane by phase-inversion process. Attachment of the PAM chains on membrane surface was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The grafted density of PAM was calculated to be 0.08 chains nm−2. Field emission scanning electron microscopy (FESEM) and atomic force microscope (AFM) were used to characterize the surface morphology of the CMPSF membrane and modified membrane. The number-average molecular weight (Mn) of PAM linearly increased with the polymerization time, while the static water contact angle (θ) of the membrane grafted with PAM linearly decreased. This indicated the hydrophilic property of the membrane was linearly correlated with the chain length of graft polymer. Therefore linear control of PSF membrane's hydrophilic property was realized through adjusting polymerization time. 相似文献
4.
Yang Zhou Shixing WangKeqiang Xie Yongnian DaiWenhui Ma 《Applied Surface Science》2011,257(24):10384-10389
Azide-functionalized chain transfer agent (CTA) was synthesized and subsequently employed to mediate the reversible addition fragmentation transfer (RAFT) polymerization of poly(ethylene glycol) monomethacrylate (PEGMA) on the alkyne-functionalized Fe3O4 nanoparticles surface together with click chemistry. In a single pot procedure, azide-functionalized CTA, alkyne-functionalized Fe3O4 and PEGMA were combined to produce the desired product. Fourier transformed infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) results showed that PEGMA chains were grafted to Fe3O4 nanoparticles using RAFT polymerization and click chemistry. 相似文献
5.
A Comparative Study of Chemical Routes for Coating Gold Nanoparticles via Controlled RAFT Emulsion Polymerization
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Sónia O. Pereira Ana Barros‐Timmons Tito Trindade 《Particle & Particle Systems Characterization》2017,34(2)
The synthesis of core‐shell Au nanoparticles protected by an amphiphilic block copolymer is investigated by distinct reversible addition fragmentation chain transfer (RAFT) emulsion polymerization routes. The controlled polymerization of polymer shells onto Au nanoparticles is attempted by using the macroRAFT (MR) agent based on 2‐(dodecylthiocarbonothioylthio)‐2‐methylpropionic acid synthesized via RAFT polymerization of poly(ethylene glycol) methyl ether acrylate and exploring several approaches, which include (i) post‐modification; (ii) in situ synthesis and (iii) “grafting from” strategies. In the conditions investigated here all these strategies lead to Au polymer nanocomposites but morphological well‐defined core‐shell nanoparticles are only obtained by applying the “grafting from” strategy. In particular, conditions that promote chain extension from the MR agent adsorbed onto the Au nanoparticles are found necessary to obtain nanostructures with such morphological characteristics and that still show the localized surface plasmon resonance typical of colloidal Au nanoparticles. 相似文献
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A facile and environmentally friendly strategy for grafting polymers onto the surface of multi-walled carbon nanotubes (CNTs) was demonstrated by Diels-Alder “click chemistry”. Firstly, the copolymers of poly(styrene-alt-maleic anhydride) (PSM) were prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization and subsequently functionalized with furfuryl amine to introduce anchoring groups. The copolymers were then grafted on CNTs via the Diels-Alder reaction in water through a conventional heating-stirring route and ultrasound-assisted method. The obtained nanocomposite materials were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The results indicated that the reaction rate under ultrasound irradiation was accelerated about 12 times than the one under the conventional heating-stirring condition without losing the grafting efficiency. The direct functionalization of CNTs formed a stably dispersed solution in water, promising a green and effective method for industrial process. 相似文献
8.
Tarik Matrab Bernadette Charleux Eva Cabet-deliry Mohamed M. Chehimi Michel Delamar 《Surface science》2007,601(11):2357-2366
Poly(n-butyl methacrylate), PBMA, chains were grafted by atom transfer radical polymerization (ATRP) from the surface of iron plates using electrochemically attached initiators based on diazonium salts providing an iron/polyphenylene/PBMA structure. This surface-initiated ATRP procedure was controlled by the addition of a small proportion of Cu++ deactivator, but in the absence of any sacrificial initiator. Combined XPS, IR and AFM experiments provide a powerful means for the characterization of the obtained complex iron/polyphenylene/PBMA layered structure. It is possible to measure the thickness of the brominated aryl structure covalently attached to iron. Concerning the PBMA brushes, their presence on the surface was confirmed by IRRAS. The brominated chain end could be traced by XPS testifying for the ATRP character of the polymerization and the thickness of the polymer brushes was determined. The controlled living ATRP character of the polymerization is confirmed through a linear correlation between the thickness of the layer and the degree of polymerization. Measurement of the grafting density of PBMA chains indicates that they are compactly packed and that, approximately, one brominated aryl chain out of two efficiently initiates ATRP. 相似文献
9.
Bechir Mrabet Minh Ngoc Nguyen Aymen Majbri Samia Mahouche Mireille Turmine Amina Bakhrouf Mohamed M. Chehimi 《Surface science》2009,603(16):2422-2429
Poly(2-hydroxyethyl methacrylate), PHEMA, brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) on silanized glass slides bearing grafted initiators. High resolution X-ray photoelectron spectroscopy (XPS) highlighted the surface chemical changes of the glass slides upon silanization and surface-confined ATRP of HEMA. Particularly, the initiator sites from the silane were detected by their bromine Br3d core electron peak whilst the O/C atomic ratios and the high resolution C1s region of the glass–PHEMA hybrids are comparable to those of pure PHEMA, thus confirming that the PHEMA chains have indeed attached to the surface. The glass–PHEMA hybrids were found to behave as anti-fouling ultrathin coatings as they resisted non-specific Salmonella typhimurium bacterial adhesion. This behaviour is driven by the hydrophilic properties of the glass–PHEMA hybrids which were assessed by contact angle measurements. In contrast, after activation of PHEMA brushes by S. typhimurium antibodies through the trichlorotriazine coupling procedure, the bacteria specifically and strongly attached to the PHEMA-coated glass slides as judged from optical microscope observation. 相似文献
10.
Copolymer brushes growing onto magnetic nanoparticles were prepared by surface chain transfer free radical polymerization. Block copolymer brushes (P(PEGMA)-co-PNIPAAm) consist of poly(ethylene glycol) monomethacrylate (PEGMA) and N-isopropylacrylamide monomer. X-ray photoelectron spectroscopy (XPS) characterized the chemical composition of copolymer. Thermogravimetric analysis (TGA) suggested that the amount of copolymer on magnetic nanoparticles decreased with increasing azodiisobutyronitrile (AIBN). The saturation magnetization decreased significantly with increasing P(PEGMA)-co-PNIPAAm. The thermosensitive point is about 43 °C for magnetic nanoparticles with 33.8% P(PEGMA)-co-PNIPAAm. 相似文献
11.
The objective of this work is to investigate the fundamentals of surface-initiated atom transfer radical polymerization (s-ATRP) on metal substrates. Acrylic polymers were grafted from active metal surfaces such as cold rolled steel (CRS), stainless steel (SS) and nickel (Ni) through s-ATRP. Severe deactivation was found with copper bromide bipyridine catalyst. Controlled polymerization with relatively low polydispersities, 1.18-1.35, was achieved using iron bromide triphenylphosphine catalyst. Polymer films up to 80 nm in thickness were obtained within 80 min. Grafting densities were estimated to be 0.58 chains/nm2 for CRS-g-PMMA, 0.55 chains/nm2 for Ni-g-PMMA, 0.18 chains/nm2 for SS-g-PMMA, and 0.66 chains/nm2 for SS-g-PDMAEMA. Electrochemical experiments were also carried out to measure the polarization resistance and corrosion potential of CRS-g-PMMA substrates. Metal surfaces with grafted brush polymer coatings showed significant corrosion resistance. This work demonstrated that the surface-initiated ATRP is a versatile means for the surface modification of active metals with well-defined and functionalized polymer brushes. 相似文献
12.
《Composite Interfaces》2013,20(8):701-714
To investigate the influence of the grafting density and the molecular structure of block copolymers on the interfacial assembly behavior and interfacial shear strength, macromolecular coupling agents, hydroxyl-terminated poly(n-butyl acrylate-b-styrene) (HO-P(BA-b-S)) were synthesized by atom transfer radical polymerization, and then chemically anchored on the glass fiber surfaces to form a well-defined monolayer. The phase separation and 'hemispherical' domain morphologies of diblock copolymer brushes at the polystyrene/glass fiber interface were observed. The interfacial assembly morphology differs with changes in the grafting density of diblock copolymers. When the grafting density is greatest, the highest height difference of the hemispherical domain and the largest surface roughness are achieved, as well as the best interface shear strength. It was also found that the copolymer brush with a PBA block of the polymerization degree (Xn) about 77 is the optimal option for the interfacial adhesion of PS/GF composites. Thus, the grafting density and molecular structure of diblock copolymers determines the interfacial assembly behavior of copolymer brushes, and therefore the interfacial shear strength. 相似文献
13.
The dispersion polymerization of styrene has been carried out using polystyrene-block-poly(4-vinylpyridine) copolymer [P(S-b-4VP)], prepared by a reversible addition-fragmentation chain transfer (RAFT) method, as a steric stabilizer in alcohol media. These block copolymer contains a long poly(4-vinylpyridine) block and a short polystyrene block. The stable spherical particles were obtained when the block copolymer concentrations increased from 2 to 20 wt.% relative to the monomer and the average particle sizes decreased from 340 to 200 nm with increasing concentration of the block copolymer. Alcoholic solvents, from methanol to n-hexanol, are responsible for the particle size. These results indicate that the poly(S-b-4VP) block copolymer is effective for providing polystyrene nano-sized particles with a low content of it working as a good stabilizer in any kind of alcoholic medium. 相似文献
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Huan Liu Wei Hu Zijing Zhang Leming Zhu 《Journal of Macromolecular Science: Physics》2014,53(9):1505-1521
Glycidyl methacrylate (GMA), a functionalized agent that can chemically link to TiO2 nanomaterial (n-TiO2), was used to modify the surface of n-TiO2 via a Ti-ethereal bond, yielding a GMA-modified n-TiO2 (mn-TiO2). Then the GMA bonded to the TiO2 surface was copolymerized with methyl methacrylate (MMA) via a reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of the RAFT agent S-1-dodecyl-S′-(α, α′- dimethyl -α″-acetic acid)trithiocarbonate (DDACT) to form mn-TiO2-PMMA nanoparticles. The resulting mn-TiO2 nanoparticles and mn-TiO2-PMMA nanoparticle materials were characterized by using infrared spectroscopy (IR), thermal analysis, and electron microscopy. The mn-TiO2 nanoparticles demonstrated good dispersive capacity in organic solvents. The results of TGA indicated that the amount of PMMA grafted onto the surface of TiO2 increased with the polymerization time. Additonally, the effects of mn-TiO2/PMMA on the thermal and mechanical properties of polypropylene were studied. 相似文献
16.
Grande CD Tria MC Felipe MJ Zuluaga F Advincula R 《The European physical journal. E, Soft matter》2011,34(2):15-10
The synthesis of homopolymer and diblock copolymers on surfaces was demonstrated using electrodeposition of a methacrylate-functionalized
carbazole dendron and subsequent reversible addition-fragmentation chain transfer (RAFT) “grafting-through” polymerization.
First, the anodically electroactive carbazole dendron with methacrylate moiety (G1CzMA) was electrodeposited over a conducting
surface (i.e. gold or indium tin oxide (ITO)) using cyclic voltammetry (CV). The electrodeposition process formed a crosslinked layer of
carbazole units bearing exposed methacrylate moieties. This film was then used as the surface for RAFT polymerization process
of methyl methacrylate (MMA), styrene (S), and tert-butyl acrylate (TBA) in the presence of a free RAFT agent and a free radical
initiator, resulting in grafted polymer chains. The molecular weights and the polydispersity indices (PDI) of the sacrificial
polymers were determined by gel permeation chromatography (GPC). The stages of surface modification were investigated using
X-ray photoelectron spectroscopy (XPS), ellipsometry, and atomic force microscopy (AFM) to confirm the surface composition,
thickness, and film morphology, respectively. UV-Vis spectroscopy also confirmed the formation of an electro-optically active
crosslinked carbazole film with a p \pi - p* \pi^{{\ast}}_{} absorption band from 450-650nm. Static water contact angle measurements confirmed the changes in surface energy of the ultrathin
films with each modification step. The controlled polymer growth from the conducting polymer-modified surface suggests the
viability of combining electrodeposition and grafting-through approach to form functional polymer ultrathin films. 相似文献
17.
A versatile method was developed for the chain-end functionalization of the grafted polymer chains for surface modification of nanoparticles with functionalized groups through a combination of surface-initiated atom-transfer radical polymerization (ATRP) and Huisgen [3 + 2] cycloaddition. First, the surface of SiO2 nanoparticles was modified with poly(methyl methacrylate) (PMMA) brushes via the “grafting from” approach. The terminal bromides of PMMA-grafted SiO2 nanoparticles were then transformed into an azide function by nucleophilic substitution. These azido-terminated PMMA brushes on the nanoparticle surface were reacted with alkyne-terminated functional end group via Huisgen [3 + 2] cycloaddition. FTIR and 1H NMR spectra indicated quantitative transformation of the chain ends of PMMA brushes onto SiO2 nanoparticles into the desired functional group. And, the dispersibility of the end-functional polymer-grafted SiO2 nanoparticles was investigated with a transmission electron microscope (TEM). 相似文献
18.
Harry J. Barraza Levent Aktas Edgar A. O’Rear M. Cengiz Altan 《Composite Interfaces》2017,24(2):125-148
Adequate stress transfer between the inorganic reinforcement and surrounding polymeric matrix is essential for achieving enhanced structural integrity and extended lifetime performance of fiber-reinforced composites. The insertion of an elastomeric interlayer helps increase the stress-transfer capabilities across the fiber/matrix interface and considerably reduces crack initiation phenomena at the fiber ends. In this study, admicellar polymerization is used to modify the fiber/matrix interface in glass woven fabric composites by forming thickness-controlled poly(styrene-co-isoprene) coatings. These admicellar interphases have distinct characteristics (e.g. topology and surface coverage) depending on the surfactant/monomer ratios used during the polymerization reaction. Overall, the admicellar coatings have a positive effect on the mechanical response of resin transfer molded, E-glass/epoxy parts. For instance, ultimate tensile strength of composites with admicellar sizings improved 50–55% over the control-desized samples. Interlaminar shear strength also showed increases ranging from 18 to 38% over the same control group. Interestingly, the flexural properties of these composites proved sensitive to the type of interphase formed for various admicellar polymerization conditions. Higher surface coverage and film connectedness in admicellar polymeric sizings are observed to enhance stress transfer at the interfacial region. 相似文献
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A Pd catalyst bearing acetylacetone ligand [(CH3CO)2CHPdCl2] was covalently attracted onto the surface of glass slides, and then these Pd-terminated glass slides were immersed into a toluene solution of norbornene (NB) to produce a vinyl-type addition polynorbornene (PNB) layer on the surface of glass slides. It was found that the contract angles of the PNB-terminated glass slides surface increased with the increasing of polymerization time, and the thickness of the PNB layers were approximately 0-44.0 μm when the polymerization time was 0.5-24 h. The researching on etching also has been operated. 相似文献