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1.
Styrene polymer/ZnO nanocomposite latex was fabricated using miniemulsion polymerization in the presence of coupling agent
3-aminopropyltriethoxysilane (APTES) and hexadecane as hydrophobe. The size distribution and morphology of the composite latex
particles were characterized by dynamic light scattering and transmission electron micrograph. X-ray photoelectron spectroscopy
and Fourier transform infrared spectrophotometer results demonstrate that ZnO nanoparticles were encapsulated into polymer
phases. The coupling treatment of ZnO with APTES can improve the dynamic contact angles of ZnO nanoparticle with water to
enhance its hydrophobicity. When 0.6% APTES to ZnO (wt/wt) is used to modify ZnO, the encapsulation efficiency of ZnO reaches
to 95%. It shows that the high encapsulation efficiency improves dispersion of ZnO nanoparticles in polymer film by scanning
electron microscope. The stable structural hybrid latex can adequately exert unique function of nanoparticles in coatings.
It indicates that the coatings added the composite latex exhibits perfect antibacterial activity, which has a tremendous potentiality
in the field of coating materials. 相似文献
2.
Ali Reza Mahdavian Yaser Sehri Hamid Salehi-Mobarakeh 《European Polymer Journal》2008,44(8):2482-2488
The encapsulation of inorganic particles with polymers is desirable for many applications in order to improve the stability of the encapsulated products and disperse ability in different media. Colloidal particles with magnetic properties have become increasingly important both technologically and for fundamental studies. This is due to their tunable anisotropic. In the absence of an applied magnetic field, the particles have isotropic sphere dispersion, whereas in an external magnetic field the particles form anisotropic structures. Here, latexes containing nanocomposite particles of styrene-butyl acrylate/Fe3O4 with core-shell structure were prepared through miniemulsion polymerization technique. Magnetic composite nanospheres with high magnetic content were synthesized through miniemulsion polymerization using a new process based on a three-steps preparation route including two miniemulsion processes: (1) preparing a dispersion of oleic acid coated magnetite particles in water; (2) mixing of modified magnetite particles with styrene/butyl acrylate in the presence of sodium dodecyl sulfate (SDS), sorbitane mono oleate (Span 80), hexadecane (HD) and (3) miniemulsification of the modified Fe3O4 into the monomer droplets to reach to complete encapsulation. Subsequent polymerization generated magnetic nanocomposite spheres. Hence, the copolymerization reaction was performed on the surface of such particles in order to obtain core-shell morphology for these nanoparticles, which were characterized by several techniques such as TEM, SEM, DLS, TGA, VSM and FT-IR. The magnetic copolymer particles with diameter of 120-170 nm were obtained. The effect of several parameters such as magnetite, surfactants and hydrophobe amounts on the stability, particle size and magnetization were investigated and also optimized. 相似文献
3.
Micron-sized nonspherical polymer particles having different morphologies were synthesized by seeded soap-free emulsion polymerization of styrene(St) and ethyleneglycol dimethacrylate(EGDMA,used as a crosslinker) on spherical, linear polystyrene(PS) seed particles.The morphology of the resulting PS/poly(St-co-EGDMA) particles was dependent on the crosslinker concentration and polymerization temperature. 相似文献
4.
Poly(styrene-co-divinylbenzene) microspheres having a diameter range of 3.0–4.5 µm were synthesized by precipitation polymerization under various conditions, then the effects of the polymerization parameters such as monomer and initiator concentration, and used cosolvents on the characteristics of the final particles were compared with those in dispersion polymerization. It was found that precipitation polymerization is more sensitive to polymerization conditions than dispersion polymerization, and that precise control of polymerization parameters is therefore essential for individually stable spherical particles. Monomer and initiator concentration, and the use of cosolvents significantly vary the morphology and the size of the final particles. However, the uniformity of the microspheres is not greatly affected by the polymerization parameters. 相似文献
5.
Chemical based approach for the synthesis of poly(styrene-co-acrylonitrile)/ZnO nanocomposites with different ZnO nanoparticle content by in situ emulsion polymerization is discussed. A significant increase in the thermal degradation temperature, melting and crystallization temperatures in all nanocomposite is observed. Increasing ZnO loading to polymer matrix enhances the flame retardant ability of polymer matrix with an appreciable increase in thermal degradation temperature of pristine polymer. 相似文献
6.
Poly(acrylamide-co-acrylic acid) nanocomposite physical (P(AAm-co-AAc)NCP) hydrogels have been prepared through the in situ free radical solution polymerization based on a “single network, dual cross-linkings” strategy. The P(AAm-co-AAc) NCP hydrogels are composed of nanobrushes of P(AAm-co-AAc) chains grafted on the surface of vinylhybrid silica nanoparticles (VSNPs). In the hydrogel system, the VSNPs act as the “analogous chemical cross-linking points” once the hydrogen bonds formed between the P(AAm-co-AAc) chains of the nanobrushes, thus leading to the fabrication of high-strength P(AAm-co-AAc) NCP hydrogels. Compared with conventional thermosensitive P(AAm-co-AAc) hydrogels, the P(AAm-co-AAc) NCP hydrogels have a broader range of phase transition temperature, which can be adjusted by altering the monomer ratio, the VSNPs concentration, the addition of urea and N,N-dimethylacrylamide (DMAAm). At the same time, the mechanical properties of the P(AAm-co-AAc) NCP hydrogels have been improved significantly by the introduction of VSNPs. Furthermore, both the phase transition and the tensile strength of the P(AAm-co-AAc) NCP hydrogels are largely influenced when Fe3+ ions are introduced as the ionic crosslinkers into the hydrogel networks. 相似文献
7.
Hollow micron-sized poly(styrene-co-divinylbenzene) particles were produced in seeded emulsions in the presence of swelling solvents. The size and morphology
of the resulting polymer particles can be altered by varying swelling solvent in seeded polymerization at elevated temperature.
The effects of swelling agents, including hydrophobic solvents, hydrophilic solvents and solvent mixtures, on the microstructure
of particles were investigated. The formation of hollow poly(styrene-co-divinylbenzene) particles depended significantly on a fast and effective phase separation between the cross-linked shell
and the swollen core, that occurred only in the presence of an appropriate swelling solvent. 相似文献
8.
E. V. Chernikova P. S. Terpugova E. S. Garina V. B. Golubev 《Polymer Science Series A》2007,49(2):108-119
The free-radical bulk homopolymerization of styrene and n-butyl acrylate at 80°C mediated by dibenzyl trithiocarbonate, poly(styryl) trithiocarbonate, or poly(n-butyl acrylate) trithiocarbonate as reversible addition-fragmentation chain-transfer agents has been studied. It has been shown that the use of low-and high-molecular-mass reversible addition-fragmentation chain-transfer agents makes it possible to efficiently control the molecular-mass characteristics of polymers. In the case of styrene, the rate of polymerization slightly depends on the concentration of the addition-fragmentation chain-transfer agent. In contrast, for the polymerization of n-butyl acrylate, the rate significantly decreases with the concentration of the chain-transfer agent. Formation of radical intermediates during the polymerization of styrene and n-butyl acrylate mediated by trithiocarbonates has been studied by ESR spectroscopy. It has been demonstrated that the polymeric chain-transfer agents are efficient for the synthesis of block copolymers with the controlled block length. 相似文献
9.
Two polystyrene-based capillary monolithic columns of different length (50 and 250 mm) were used to evaluate the effects of
column length on gradient separation of protein digests. A tryptic digest of a 9-protein mixture was used as a test sample.
Peak capacities were determined from selected extracted ion chromatograms, and tandem mass spectrometry data were used for
database matching using the MASCOT search engine. Peak capacities and protein identification scores were higher for the long
column with all gradients. Peak capacities appear to approach a plateau for longer gradient times; maximum peak capacity was
estimated to be 294 for the short column and 370 for the long column. Analyses with similar gradient slope produced a ratio
of the peak capacities of 3.36 for the long and the short column, which is slightly higher than the expected value of the
square root of the column length ratio. The use of a longer monolith improves peptide separation, as reflected by higher peak
capacity, and also increases protein identification, as observed from higher identification scores and a larger number of
identified peptides. Attention has also been paid to the peak production rate (PPR, peak capacity per unit time). For short
analysis times, the short column produces a higher PPR, while for analysis times longer than 40 min, the PPR of the 250-mm
column is higher. 相似文献
10.
E. V. Chernikova N. S. Serkhacheva O. I. Smirnov N. I. Prokopov A. V. Plutalova E. A. Lysenko E. Yu. Kozhunova 《Polymer Science Series B》2016,58(6):629-639
The effect of the chain length of oligomer acrylic acid obtained in the presence of a low-molecularmass trithiocarbonate and the position of trithiocarbonate fragment (within the chain or at the chain end) on the process of emulsion polymerization of n-butyl acrylate and characteristics of the resulting dispersions has been studied for the first time. It has been found that, when using an oligomer with trithiocarbonate group located within the chain in the emulsion polymerization of n-butyl acrylate in a wide range of monomer–water phase compositions, triblock copolymers self-organizing in aqueous medium to give stable particles with the core–shell structure are formed. Oligomers with M n ~ (5–10) × 103 are optimal for synthesis of stable dispersions. In this case, block copolymers with the controlled length of hydrophobic block and a rather narrow MWD may be obtained. Thin films formed from these copolymers retain the structure of the initial dispersions on solvent removal. If the trithiocarbonate group in the oligomer is located at the chain end, the main polymerization product is a diblock copolymer. In this case, the formation of polymer–monomer particles occurs during a longer period of time, the control of MWD is weakened, and the dispersions of particles lose the aggregative stability after thin film formation. 相似文献
11.
Cationic poly(styrene-co-N,N-dimethylaminoethyl methacrylate) (P(St-co-DMAEMA)) latexes were prepared in the absence of surfactant by using 2,2’ -azobis (2-methylpropionamidine) dihydrochloride (AIBA) as the initiator. The effects of the AIBA concentration, HCl/DMAEMA molar ratio and DMAEMA amount on the emulsion polymerization and the latex properties were investigated. The particle morphology and size, the zeta potential and the amino distribution of the P(St-co-DMAEMA) latexes were characterized by transmission electron microscope (TEM), dynamic light scattering (DLS) and conductometric titration, respectively. Results showed that the emulsion polymerization performed smoothly with high monomer conversion and narrow particle size distribution under the optimized conditions with AIBA concentration of 1 wt%, HCl/DMAEMA molar ratio of 1.2 and DMAEMA content of 5 wt%. The diameter of the dried latex particles decreased and the density of amino groups on the particle surfaces increased with increasing the DMAEMA content. The zeta potential of the P(St-co-DMAEMA) latexes was pH-dependent and the zero point was around at pH 7.2. A facile method was developed to fabricate P(St-co-DMAEMA)/laponite hybrid nanoparticles via electrostatic adsorption, in which the loading capacity of laponite platelets reached 17.7 wt%, and the resultant hybrid nanoparticles showed good thermal stability. 相似文献
12.
The morphology and thermomechanical properties of well-defined polyethylene-graft-poly(n-butyl acrylate) (PE-g-PBA) copolymers prepared via atom transfer radical polymerization were investigated. Differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), wide angle X-ray scattering (WAXS), dynamic mechanical measurement and large deformation tensile tests were performed on the graft copolymers and the results were compared with the behavior of the polyethylene macroinitiator. The existence of both crystalline polyethylene segments and amorphous poly(n-butyl acrylate) segments in the copolymers leads to microphase separation and unique thermomechanical behavior. Strong microphase separation was observed by DSC and X-ray diffraction studies. Correlation of morphology and thermomechanical properties was also studied using dynamic mechanical measurement and large deformation tensile tests.Dedicated to Prof. E. W. Fischer on the occasion of his 75th birthday 相似文献
13.
Roghayeh Shabanlouei Peyman Najafi Moghadam Nasim Movagharnezhad Amir Reza Fareghi 《Polymer Science Series B》2016,58(5):574-579
In the present work new conductive nanostructures based on poly (acrylamide-co-maleic acid) (PAAMA) and polyaniline were prepared. The template polymerization of aniline was conducted in the aqueous solution of PAAMA with different ratios (w/w%) of aniline to polyacid. The prepared composite was characterized by FTIR and UV–Vis spectroscopy, SEM, electrical conductivity measurements and solubility tests. 相似文献
14.
Wenzhong Ma Jun Zhang Shuangjun Chen Xiaolin Wang 《Colloid and polymer science》2008,286(10):1193-1202
Poly (styrene-co-acrylonitrile) (SAN) is a hydrophilic non-crystalline copolymer, which is initially used in this paper to improve the hydrophilicity
of poly (vinylidene fluoride) (PVDF). Investigation of the crystallization behavior of PVDF/SAN blends showed that the samples
presented only α phase regardless of SAN content as cooling from the melt. A double-melting phenomenon was related to the
perfection or crystal size of PVDF crystals. As the SAN content is increasing, crystallization of PVDF was limited, leading
to a decreased crystallinity and lamellar growth. Besides, the hydrophilicity of PVDF was improved by blending with SAN. The
sample containing 70 wt.% SAN performed a similar surface property of the neat SAN owing to the besieging of the PVDF phase
by SAN. Observed from the cross section of the blends, PVDF/SAN blends were partially miscible with less than 50 wt.% SAN
addition. As the SAN content was more than 50 wt.%, the crystalline PVDF particles clearly dispersed in the amorphous matrix. 相似文献
15.
In order to exploit the biological functions of materials, a series of new random terpolymers were synthesized by the ring-opening polymerization of p-dioxanone, trimethylene carbonate, and L-phenylalanine N-carboxyanhydride (L-Phe- NCA) in the presence of stannous octoate. The terpolymers were characterized by 1H-NMR, 13C-NMR, FTIR, and gel permeation chromatography. The effects of the reactant ratio, catalyst dosage, reaction temperature and time on the copolymerization were investigated, and were found to regulate the composition of the terpolymer. Increases in the reaction temperature, polymerization time, L-Phe-NCA monomer amount, and catalyst content generated a product with a slightly decreased molecular weight. The crystallinity of the terpolymer was investigated by differential scanning calorimetry and polarized optical microscopy. A reasonable mechanism for the polymerization was proposed based on the obtained results. 相似文献
16.
Janakiraman Vivekanandan Arunachalam Mahudeswaran Xiao-Yan Tang Sangamesh G. Kumbar Pachanoor Subbaian Vijayanand 《Chemical Papers》2015,69(7):964-972
Novel copolymers of poly(aniline-co-m-chloroaniline)-doped dodecylbenzenesulphonic acid (DBSA) with embedded silver nanoparticles were synthesised using the in situ chemical oxidative method. The structural properties of the copolymers were characterised using the UV-VIS and FTIR spectroscopic methods. The crystalline nature of the copolymer was demonstrated by way of the X-ray diffraction (XRD) pattern. Scanning electron microscopy (SEM) revealed the presence of particle agglomerates measuring 50 nm to 100 nm on the surface of the nanocomposites. The electrical conductivity of the copolymer was dependent on the monomer composition and was found to be in the range of 10?2 S cm?1 to 10?6 S cm?1 with an increasing chloroaniline content and exhibiting improved solubility. 相似文献
17.
The ring opening polymerization of ε-caprolactone (CL) was initiated by glycol and yttrium tri(2,6-di-tert-butyl-4-methylphenolate)s (Y(OAr)3), preparing dihydroxy-capped poly (ε-caprolactone) (PCL) with controllable molecular weight. 1H NMR and SEC analyses indicate that two kinds of active species and corresponding PCL with different structures exist in
the system. Increasing the ratio of glycol to Y(OAr)3 benefits the formation of monofunctional active species. However, poly(ethylene glycol) (PEG)/Y(OAr)3 system only contains sole bifunctional active species to synthesize copolymer of CL with PEG (poly(CL-b-PEG-b-CL)). Dihydroxycapped PCL as macroinitiator can further initiate the polymerization of 2,2-dimethyltrimethylene carbonate
(DTC). Thus, triblock copolymer of CL with DTC (poly(DTC-b-CL-b-DTC)) has been prepared. 相似文献
18.
In this article, we report the experimental synthesis of reactive polymer microspheres of poly(p-hydroxycinnamic acid). Enzyme-catalyzed polymerization of poly(p-hydroxycinnamic acid) using horseradish peroxidase as a catalyst and hydrogen peroxide as an oxidant took place in a mixture solution of methanol and phosphate buffer solution; it was found that the fraction of methanol in the mixture solution strongly affected the yield of powdery polymer materials. The chemical structure of the polymers was characterized by 1H-NMR and FT-IR spectroscopies, and the molecular weight was measured by gel permeation chromatography. The 1H-NMR chart of the obtained polymer was almost the same as that of the monomer; FT-IR spectra indicated the existence of carboxyl groups. The weight-average molecular weight of the soluble part in tetrahydrofuran was found to be 1,451. Dispersion polymerization of p-hydroxycinnamic acid was carried out in a mixture solution of methanol and phosphate buffer solution by adding a dispersion stabilizer. Of the several such polymers tested, poly(vinyl alcohol) was found to be the most effective in producing reactive poly(p-hydroxycinnamic acid) microspheres. 相似文献
19.
Compatibilization of the partially miscible poly(vinylidene fluoride) (PVDF)/poly(styrene-co-acrylonitrile) (SAN) pair by a third homopolymer, i.e., poly(methyl methacrylate) (PMMA), was investigated in relation to
cross section morphology, crystallization behaviors and hydrophilicity of the polyblends. Scanning electron microscopy showed
a more regular and homogeneous morphology when more than 15 wt.% PMMA was incorporated. The samples presented only α phase
regardless of PMMA content in the blend. As the PMMA content increased in the blends, the interactions between each component
were enhanced, and the crystallization of PVDF was limited, leading to a decreasing of the crystallinity and the crystallite
thickness. Besides, the hydrophilicity of PVDF was further improved by PMMA addition. The sample containing 15 wt.% PMMA showed
a more hydrophilic property due to the more polar part of surface tension induced by PMMA addition. Observed from the cross
section of the blends, the miscibility of partially miscible PVDF/SAN blends were efficiently improved by PMMA incorporation. 相似文献
20.
This work successfully prepared nanohybrids by in situ atom transfer radical polymerization (ATRP) of styrene from titanate nanotubes (TNTs). Fourier-transform infrared (FT-IR),
pronton nuclear magnetic resonance spectroscopy (1H NMR), and thermal gravimetric analysis (TGA) were used to verify the successful graft of polystyrene (PS) chains from TNTs.
Transmission electron microscopy (TEM) displayed that the obtained PS-g-TNTs nanohybrids had a core-shell structure of TNT core and PS shell. The grafted PS content was well controlled and increased
with increasing of the monomer/initiator ratio. Further copolymerization of tert-butyl acrylate (tBA) from the surface of PS-g-TNTs was studied, illustrating the “living” characteristics of the surface-induced ATRP method used in this work.
Supported by the Special Funds for Major State Basic Research Projects (Grant No. 2005CB623803), the National Basic Research
Program (Grant Nos. 2007CB808000 & 2009CB930400), the National Natural Science Foundation of China (Grant Nos. 50633010 &
20874060), the Program for New Century Excellent Talents in University (Grant No. NCET-07-0558), the Basic Research Foundation
of Shanghai Science and Technique Committee (Grant No. 07DJ14004), and Shanghai Leading Academic Discipline Project (Grant
No. B202). 相似文献