共查询到20条相似文献,搜索用时 15 毫秒
1.
Mehdi Jaymand 《Polymer》2011,52(21):4760-4769
This paper describes the synthesis and characterization of novel type poly (4-chloromethyl styrene-graft-4-vinylpyridine)/TiO2 nanocomposite. Firstly, poly (4-chloromethyl styrene)/TiO2 nanocomposite was synthesized by in situ free radical polymerizing of 4-chloromethyl styrene monomers in the presence of 3-(trimethoxysilyl) propylmethacrylate (MPS) modified nano-TiO2. Thereafter, 1-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO-OH) was synthesized by the reduction of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). This functional nitroxyl compound was covalently attached to the poly (4-chloromethyl styrene)/TiO2 with replacement of chlorine atoms in the poly (4-chloromethyl styrene) chains. The controlled graft copolymerization of 4-vinylpyridine was initiated by poly (4-chloromethyl styrene)/TiO2 nanocomposite carrying TEMPO groups as a macroinitiators. The coupling of TEMPO with poly (4-chloromethyl styrene)/TiO2 was verified using 1H nuclear magnetic resonance (NMR) spectroscopy. The obtained nanocomposites were studied using transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and the optical properties of the nanocomposites were studied using ultraviolet-visible (UV-Vis) spectroscopy. 相似文献
2.
S. Monteiro A. Dias A.M. Mendes J.P. Mendes A.C. Serra N. Rocha J.F.J. Coelho F.D. Magalhães 《Progress in Organic Coatings》2014
In this work, TiO2 nanoparticles were dispersed and stabilized in water using a novel type of dispersant based on tailor-made amphiphilic block copolymers of poly(ethylene glycol)-block-poly(4-vinyl pyridine) (mPEG-b-P4VP) prepared by atom transfer radical polymerization (ATRP). The performance of this new block copolymer as dispersant was compared to a polyelectrolyte dispersant commonly used for TiO2, sodium salt of polyacrylic acid (Na-PAA). The effect of dispersion technique and type and amount of dispersant on deagglomeration and stability of the TiO2 aqueous suspensions were studied. After incorporation in a standard waterborne acrylic varnish formulation, dry film transparency, photocatalytic activity, and nanoparticle cluster size were also evaluated. The results show that mPEG-b-P4VP copolymer with appropriate block lengths can have a better performance than Na-PAA in terms of aqueous dispersion stabilization and cluster size reduction in the acrylic matrix. This translates into higher film transparency and photocatalytic performance. 相似文献
3.
Glaucione Gomes De Barros Maria Jos Araújo Sales Ana Regina Feitosa De Britto 《Polymer Engineering and Science》1996,36(8):1125-1128
The structures of low-density polyethylene (LDPE) modified by in situ sorption and thermal polymerization of 4-vinylpyridine (4VP) and of methyl methacrylate (MMA) were studied. The phase behavior of these materials was investigated by means of X-ray diffraction, scanning electron microscopy (SEM), and by thermal measurements (DSC). The diffraction studies indicated that the polymerization occurs at the amorphous domains of the matrix, except for the case of 4VP (168.0%), in which polymerization at the crystalline domains of LDPE matrix was also observed. These materials showed at least two Tg values, indicating microphase separation. The morphology of LDPE-P4VP was different from that of LDPE-PMMA. 相似文献
4.
This paper reports the development of a high-impact epoxy nanocomposite toughened by the combination of poly(acrylonitrile-co-butadiene-co-styrene) (ABS) as thermoplastic, clay as layered nanofiller, and nano-TiO2 as particulate nanofiller. Response surface methodology (RSM) was applied for optimization and modeling of the impact strength
of epoxy/ABS/clay/TiO2 quaternary nanocomposite. A second-order mathematical model between the response (impact strength) and variables (ABS, clay
and nano-TiO2 contents) was derived. Analysis of variance (ANOVA) showed a high coefficient of determination value (R
2 = 98%). Under optimum conditions, maximum impact strength of 29.2 KJ/m2 with 197% increase compared to neat epoxy was experimentally obtained. Also correlation between morphology and impact strength
of the nanocomposite was investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). A dispersion of
exfoliated clay platelets, TiO2 nanoparticles with low agglomeration and ABS nanoparticles was obtained as morphology of the nanocomposite. A new and more
effective method for impact toughening of epoxy was introduced. This study clearly showed that the addition of the combination
of layered and particulate nanofillers along with ABS as thermoplastic has a considerable enhancement effect on impact strength
of epoxy. 相似文献
5.
Well-defined polymer-TiO2 nanocomposites of core–shell structure were prepared by two-steps, surface-initiated atom transfer radical polymerization (ATRP) of styrene and in situ chemical oxidative polymerization of aniline monomers from the surfaces of the TiO2 nanoparticles. The methods used include the following: initially, the ATRP initiator was covalently attached to the surface of TiO2 nanoparticles by esterification of 2-bromo-2-methyl propionic acid with hydroxyl group. The metal-catalyzed radical polymerization of styrene with modified TiO2 nanoparticles was performed using a copper catalyst system to give the TiO2-based core hybrids linking PSt segments (TiO2-PSt hybrids). Next, the TiO2-PSt reacted with HNO3/H2SO4 to produce a nitro group containing polystyrene to form TiO2-PSt-NO2, and obtained TiO2-PSt-NO2 was treated with hydrochloric acid/SnCl2, and converted to an amine group containing polystyrene (TiO2–PSt-NH2). Finally, surface oxidative graft copolymerization of aniline, using the –NH2 moieties of TiO2/PSt-NH2 as the anchoring sites. Characterization of these well-defined nanocomposites included FTIR, thermogravimetric analysis, transmission electron microscopy, and X-ray diffraction. 相似文献
6.
Double In Situ Approach for the Preparation of Polymer Nanocomposite with Multi-functionality 总被引:1,自引:0,他引:1
De-Yi Wang Yan-Peng Song Jun-Sheng Wang Xin-Guo Ge Yu-Zhong Wang Anna A. Stec T. Richard Hull 《Nanoscale research letters》2009,4(4):303-306
A novel one-step synthetic route, the double in situ approach, is used to produce both TiO2 nanoparticles and polymer (PET), and simultaneously forming a nanocomposite with multi-functionality. The method uses the
release of water during esterification to hydrolyze titanium (IV) butoxide (Ti(OBu)4) forming nano-TiO2 in the polymerization vessel. This new approach is of general significance in the preparation of polymer nanocomposites,
and will lead to a new route in the synthesis of multi-functional polymer nanocomposites. 相似文献
7.
Miao Wu Feimin Zhang Jiahui Yu Hongye Zhou Di Zhang Chong Hu Jin Huang 《Iranian Polymer Journal》2014,23(7):513-524
A kind of light-curing nanocomposite resin, which consisted of reactive monomers, surface-modified TiO2 nanoparticles and a photoinitiation system, has been developed for the application of dental restoration. It may be noted that the conjugation of glycidyl methylmethacrylate (GMA) onto the surface of TiO2 nanoparticles (nano-TiO2) contributed to improvement in miscibility between nano-filler and matrix, because the reactive C=C group of GMA participated in curing of the matrix, and hence resulted in the enhancement of mechanical properties. When the content of GMA-modified nano-TiO2 was 2 wt%, the flexural strength and modulus of the nanocomposite resin reached 147.8 and 2918.3 MPa, respectively, which increased by 21.7 and 30.8 % in contrast to the resin without adding nano-filler. Furthermore, the polymerization shrinkage decreased after incorporating the nano-filler while the degree of monomer conversion and the water sorption for the nanocomposite resins was comparable with those of the resin without nano-filler. In conclusion, this study presented a new method, namely introduction of functional groups onto the nano-filler surface to participate in the reaction of resin monomer, to improve the interfacial adhesion and the resultant miscibility between nano-filler and resin matrix in light-curing dental nanocomposites by chemical linkage mediated with surface-modified specie. Moreover, the enhanced mechanical properties and decreased polymerization shrinkage of nanocomposite resins, which are considered the key to the effects of dental restoration, contributed a great potential as a dental material utilized for caries treatment and prevention. 相似文献
8.
Mohammad M. Fares Mohammad El-Khateeb Khalil J. Asali 《Journal of Inorganic and Organometallic Polymers》2003,13(3):143-155
The polymerization of 4-vinylpyridine (4VP) and 4-vinylpyridine chromium pentacarbonyl [(4VP)Cr(CO)5] was performed under N2 atmosphere at 60–80°C temperature range. Different percent of feed (%PF) of Cr(CO)5 groups were anchored into poly(4-vinylpyridine) (P4VP) by addition of the intermediate Cr(CO)5THF, which was generated photochemically from Cr(CO)6 in THF, to the polymer at ambient temperature. The determined percent of anchoring (%PA) has shown that the maximum anchored Cr(CO)5 groups was 40% (w/w) with respect to P4VP, and the optimum percent of anchoring was 20% (w/w). The rate of polymerization (R
p
) and the activation energy (E
a
) of 4VP in the absence and in the presence of 16.7% Cr(CO)5(4VP) were determined. Thermal analysis has shown various changes in the properties of the 4VP polymers after modification of the polymer by Cr(CO)5 groups. The X-ray diffraction and the melting enthalpy derived from the DSC thermogram revealed that the synthesized poly[(CO)5Cr(4VP)] has a crystallinity of about 40%, whereas no crystallinity was observed for pure P4VP. 相似文献
9.
Hybrid nanocomposites of poly(2‐hydroxyethyl methacrylate) (PHEMA) and TiO2 nanoparticles were synthesized via surface thiol‐lactam initiated radical polymerization by following the grafting from strategy. Initially, TiO2 nanoparticles were modified by 3‐mercaptopropyl trimethoxysilane to prepare thiol functionalized TiO2 nanoparticles (TiO2? SH). Subsequently, surface initiated polymerization of 2‐hydroxyethyl methacrylate was conducted by using TiO2? SH and butyrolactam as an initiating system. The anchoring of PHEMA onto the surface of TiO2 nanoparticles was investigated by FTIR, 1H‐NMR, XPS, TGA, and XRD analyses. The experimental results indicated a strong interaction between PHEMA and TiO2 nanoparticles owing to covalent bonding. The TEM and SEM images of PHEMA‐g‐TiO2 showed that the agglomeration propensity of TiO2 nanoparticles was significantly reduced upon the PHEMA functionalization. The molecular weight and polydispersity index of the cleaved PHEMA from the surface of TiO2 nanocomposites were estimated by GPC analysis. An improved thermal property of the nanocomposites was observed from TGA analysis. PHEMA‐g‐TiO2 nanocomposites were found to be highly dispersible in organic solvents. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
10.
Angel Romo-Uribe 《大分子材料与工程》2021,306(2):2000591
Spatially distributed TiO2 nanoparticles induced an order of magnitude decrease of glass transition temperature, Tg, and chain disentanglement in waterborne acrylic coatings. Acrylic/TiO2 coatings are synthesized in situ by batch emulsion polymerization. The copolymer is based on butyl acrylate (BA), methyl methacrylate (MMA), and acrylic acid (AA) with composition 56:42:2 mol%, and nano-TiO2 (ca. 12 nm) is incorporated up to 3 wt% content. Transmission electron microscopy (TEM) showed that TiO2 is dispersed at nearly single unit throughout the acrylic matrix. The nanoparticle reduced Tg and broadened the temperature range of the glass transition, δTg. The considerable increase of δTg suggests gradients of dynamics. Shear rheometry demonstrated that TiO2 induced chain disentanglement, the rubbery modulus Ge decreased two orders of magnitude with only 1 wt% TiO2 content thus increasing the packing length p (and the reptation tube diameter as dt = kp, k > 1). Consequently, the tensile Young's modulus E decreased an order of magnitude, relative to the neat copolymer. The reduction of Tg, the slowdown of macromolecular dynamics, the chain disentanglement and the increase of dt suggests dynamics modification due to intercalation of the entangled web by the TiO2 nanoparticles, and these results may be ascribed to a nanoconfinement effect. 相似文献
11.
Stable nano-TiO2/polyurethane (PU) emulsions were prepared via in situ reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization of 2-hydroxyethyl acrylate (HEA)-capped PU macromonomer, using azobisisobutyronitrile (AIBN) as a radical initiator and 2-{[(butylsulfanyl)carbonothioyl]sulfanyl} propanoic acid (BCSPA) anchored onto TiO2 nanoparticles (TiO2-BCSPA) as a RAFT agent. When the molar ratio of AIBN to TiO2-BCSPA was changed from 1:3 to 1:10, the polydispersity index (PDI) of polymers in the emulsions decreased from 1.83 to 1.06, due to more effective RAFT polymerization in the emulsions. The TiO2 nanofillers were well-dispersed throughout the polymer films. The tensile strengths of the nanocomposite films were significantly enhanced due to coordination bonding between the TiO2 nanofillers and the –COOH end groups of the polymers, as evidenced by the FT-IR spectral data. 相似文献
12.
Liqin CaoYaodong Hu Lijuan ZhangChuang Ma Xiaohu WangJide Wang 《The Journal of Supercritical Fluids》2011,58(2):233-238
Compared with conventional precipitation polymerization method, cross-linked poly(4-vinylpyridine) (P4VP) and its microgels copolymerized with α-methacrylic acid (MAA) were synthesized through a new route of stabilizer-free polymerization in supercritical fluids. The yellow, dry, fine powders were directly obtained from precipitation polymerization of 4-vinylpyridine in supercritical carbon dioxide (scCO2) at pressures ranging from 70.0 to 230 bar, using N,N′-methylenebisacrylamide as cross-linker. The effects of the reaction pressure, cross-linker ratio, initiator concentration, and reaction time were investigated. The capacity of this microgel for adsorption of copper(II) was also studied. At higher cross-linker concentrations, a high yield of the cross-linked P4VP microgel was generated in scCO2, and its particle size was less than 300 nm. Polymerization of cross-linked P4VP in scCO2 was extremely sensitive to the density of the continuous phase. The adsorption followed the Langmuir isotherm. The adsorption capacities of cross-linked P(4VP-co-MAA) and cross-linked P4VP were 47.2 and 26.9 mg g−1, respectively. 相似文献
13.
Direct grafting poly(methyl methacrylate) from TiO2 nanoparticles via Cu2+‐amine redox‐initiated radical polymerization: An advantage of monocenter initiation
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Cu2+ can oxidize amines to generate radicals to initiate radical polymerization of electron‐deficient monomers under mild conditions. Here, CuSO4‐catalyzed redox‐initiated radical polymerizations of methyl methacrylate from amino‐functionalized TiO2 nanoparticles (TiO2‐NH2 nanoparticles) was performed to prepare TiO2 nanoparticles grafted with poly(methyl methacrylate) (TiO2‐g‐PMMA hybrid nanoparticles) in dimethylsulfoxide or N,N‐dimethylformamide at 90°C. Infrared spectroscopy, thermogravimetric analysis, and X‐ray photoelectron spectroscopy confirmed the presence of the grafted PMMA and the grafting yield was about 50 wt%. Microscopy and particle‐size analysis indicated that TiO2‐g‐PMMA nanoparticles had a good affinity to organic media. Because only aminyl radical (? NH?) on TiO2 nanoparticles formed in Cu2+‐amine redox‐initiation step, there was no free PMMA chains formed during polymerization. Thus, our protocol provides a facile strategy to prepare inorganic/organic hybrid nanoparticles via one‐pot Cu2+‐amine redox‐initiated free radical polymerization. POLYM. ENG. SCI., 55:735–744, 2015. © 2014 Society of Plastics Engineers 相似文献
14.
Poly(α-methylstyrene) (PMS) macromonomer having one vinylbenzyl group per polymer chain was prepared by the couplings of living PMS with p-chloromethylstyrene (CMS). Subsequently, well-defined poly[acrylic acid (AA)-g-α-methylstyrene (MS)] and poly[4-vinylpyridine (4VP)-g-MS] graft copolymers composed of polyelectrolyte trunks were prepared by radical copolymerization of PMS macromonomer with AA and 4VP monomers, respectively. Binary poly(AA-g-MS)/poly(4VP-g-MS) or poly[AA · triethyl amine (Et3N) salt-g-MS)/poly(4VP-g-MS) graft copolymer blend films were cast from a benzene/methanol mixture. The morphological results of binary graft copolymer blends are discussed with respect to three-phase separated structures. 相似文献
15.
A straightforward approach has been developed for fabricating antibacterial and antistatic epoxy coatings by using polyaniline-chitosan modified TiO2 ternary nanocomposite. This nanocomposite was synthesized through the following steps. First, chitosan was grafted onto the TiO2 nanoparticles and then final nanocomposite was prepared via solution polymerization of aniline. Electrical conductivity measurement revealed that nanocomposite with 7.5 wt % of the modified TiO2 nanoparticles has noticeably higher conductivity compared to polyaniline. Evaluating the coatings' antibacterial property indicated epoxy coatings with the content of ternary nanocomposite show significant bactericidal activity against Gram-positive bacteria and have acceptable antibacterial action against Gram-negative ones. Also, obtained results showed that the ternary nanocomposite would greatly decrease coatings' surface resistivity and when nanocomposite content is about 2 wt % surface resistivity is about 3 × 107 Ω sq−1. On the contrary, the coating with nanocomposite loading exhibits improved thermal and mechanical performance compared to the coating made of neat epoxy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47629. 相似文献
16.
Encapsulation of inorganic nanoparticles by polymers is one of the interesting research topics that lead to the synthesis of nanocomposites. These nanocomposite materials comprise the properties of both organic polymer and inorganic nanoparticles. Here, hybrid latex particles with core–shell nanostructure were prepared via semi-batch emulsion polymerization. Copolymers of (methyl methacrylate-butyl acrylate) and (dimethylaminoethyl methacrylate-butyl acrylate-acrylic acid) were formed as the inner and outer layers, respectively on the surface of modified TiO2 nanoparticles as the core. In order to create compatibility between inorganic and polymeric phases, modification of TiO2 nanoparticles was performed with glycidyl methacrylate with an optimized procedure for the first time and then emulsion polymerization was carried out. The products of each step were fully characterized. The results of dynamic light scattering, TEM and SEM analyses proved the formation of encapsulated hybrid latex particles. DLS and SEM data revealed that the sizes of nanocomposite particles vary between 85 and 120 nm for 0–5 wt% of the modified TiO2 nanoparticles. Physico-mechanical properties of the obtained nanocomposite films were studied by DMTA. It was found that using only 3 wt% of modified TiO2 improved those properties of resulting films remarkably. 相似文献
17.
Hydrophobically modified nanosilica was prepared from tetraethoxysilane (TEOS) and γ‐methacryloxypropyltrimethoxysilane (MPS) by a two step sol‐gel process. The polystyrene‐grafted‐modified nanosilica (PS‐g‐mSiO2) hybrid particles were prepared by grafting polystyrene onto the resulting hydrophobically modified nanosilica by dispersion polymerization. The hybrid nanoparticles were subsequently used as the filler to fabricate polypropyrene (PP) nanocomposites. The crystallization kinetics, crystal morphology and crystallization phase component of PS‐g‐mSiO2/PP nanocomposite were studied using a differential scanning calorimeter (DSC), polarizing optical microscopy (POM) and X‐ray diffraction (XRD). Crystallization half life (t1/2) decreased, while the Arami exponent (n) of PS‐g‐mSiO2/PP nanocomposite increased compared with that of virgin PP. A rheological study allowed the unambiguous characterization of the dispersibility of nanosilicas in PS‐g‐mSiO2/PP nanocomposite. The storage modulus, melt viscosity and the elongation to break of the PS‐g‐mSiO2/PP nanocomposite were found to be strongly dependent on the grafting of PS on nanosilicas. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers 相似文献
18.
Mohammad M. Fares Mohammad El-Khateeb Khalil J. Asali 《Journal of Inorganic and Organometallic Polymers and Materials》2003,13(3):143-155
The polymerization of 4-vinylpyridine (4VP) and 4-vinylpyridine chromium pentacarbonyl [(4VP)Cr(CO)5] was performed under N2 atmosphere at 60–80°C temperature range. Different percent of feed (%PF) of Cr(CO)5 groups were anchored into poly(4-vinylpyridine) (P4VP) by addition of the intermediate Cr(CO)5THF, which was generated photochemically from Cr(CO)6 in THF, to the polymer at ambient temperature. The determined percent of anchoring (%PA) has shown that the maximum anchored Cr(CO)5 groups was 40% (w/w) with respect to P4VP, and the optimum percent of anchoring was 20% (w/w). The rate of polymerization (R p ) and the activation energy (E a ) of 4VP in the absence and in the presence of 16.7% Cr(CO)5(4VP) were determined. Thermal analysis has shown various changes in the properties of the 4VP polymers after modification of the polymer by Cr(CO)5 groups. The X-ray diffraction and the melting enthalpy derived from the DSC thermogram revealed that the synthesized poly[(CO)5Cr(4VP)] has a crystallinity of about 40%, whereas no crystallinity was observed for pure P4VP. 相似文献
19.
A new method is presented for grafting poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (P(HEMA-co-MMA)) chains from the surface of TiO2 nanoparticles via atom transfer radical polymerization (ATRP). First, the ATRP initiators were immobilized onto the TiO2 surface by using 3-aminopropyltriethoxysilane coupling agent and 2-bromoisobutyryl bromide. Then the copolymerization of 2-hydroxyethyl methacrylate with methyl methacrylate was initiated and propagated on the TiO2 surface by ATRP. The resulting composite nanoparticles were characterized by means of XPS, FT-IR, 1H NMR, GPC and TGA. The results indicated that the grafting of copolymer chains from the TiO2 surface was successful. This method opens up new avenues for the preparation of TiO2-polymer nanocomposites. 相似文献
20.
It is found that the complexes of PS-b-P2VP and HAuCl4 in THF can form a compound vesicle when the THF solution is treated at 40 °C. The compound vesicle is composed of an insoluble
wall formed by P2VP/HAuCl4 complexes and a soluble PS shell. The vesicular character of the aggregates was investigated by dynamic light scattering
(DLS) and transmission electron microscope (TEM). The decrease of the solubility of P2VP blocks in THF drives the PS-b-P2VP/HAuCl4 complexes to aggregate into vesicles, which are stable upon dilution or crosslinking. Based on this study, the vesicles decorated
with gold nanoparticles can be produced, which hold potential for the facile organization of the vesicle-supported precious
metal catalysts. 相似文献