共查询到20条相似文献,搜索用时 15 毫秒
1.
A single-stage swelling and polymerization method was proposed for the synthesis of monodisperse porous poly(vinyl acetate-co-divinylbenzene) [poly(VAc-co-DVB)] particles with different VAc/DVB feed ratios. The particles obtained with the VAc/DVB feed ratio of 50:50 v/v had a narrow pore size distribution exhibiting a sharp peak at 30 nm. Based on this distribution the mean pore size and the specific volume were determined as 12 nm and 1.39 mL/g, respectively. The specific surface area of poly(VAc-co-DVB) particles was found to be 470 m2/g. These properties make poly(VAc-co-DVB) particles a promising support for potential HPLC applications. Poly(vinyl alcohol-co-divinylbenzene) [poly(VA-co-DVB)] particles were then obtained by the basic hydrolysis of poly(VAc-co-DVB) particles. The hydroxyl groups on poly(VA-co-DVB) particles have a suitably reactive functionality for surface grafting or derivatization protocols aiming at synthesizing various HPLC packings. The examination of poly(VA-co-DVB) particles by confocal laser scanning microscopy showed the homogeneous distribution of hydroxyl functionality in the particle interior. As a starting point, the chromatographic performance of plain material, poly(VAc-co-DVB) particles produced with VAc/DVB feed ratio of 50:50 (v/v) was tested by a commonly utilized chromatographic mode, reversed phase chromatography. Poly(VAc-co-DVB) particles were successfully used as packing material in the RP separation of alkylbenzenes with resolutions higher than 1.5. Theoretical plate numbers up to 17 500 plates/m were achieved. No significant change both in the chromatographic resolution and column efficiency was observed with increasing flow rate. The chromatography showed that poly(VAc-co-DVB) particles were a suitable starting material for the synthesis of chromatographic packings for different modes of HPLC. 相似文献
2.
Rong Long Li Cheng You Kan Ze Ping Li Yi Du Yan Nan Cui Department of Chemical Engineering Key Laboratory of Advanced Materials of Ministry of Education Tsinghua University Beijing China 《中国化学快报》2007,18(6):741-743
The effects of ionic emulsifier, sodium dodecylbenzene sulfate (SDBS), on the formation of the multihollow structures in sub-micron sized polymer particles produced by alkali/acid posttreatment were investigated. The original latex particles with narrow size distribution were synthesized by a new sequence emulsifier-free/emulsifier emulsion copolymerization of styrene (St) and methacrylic acid (MAA). Results indicated that the pore size decreased and the pore number increased with the increase of SDBS amount, and the morphology of the posttreated latex particles was also significantly influenced by the introducing time of SDBS in the preparation of the original latex particles, and a suitable introducing time was 3 h of polymerization. 相似文献
3.
Dong-ming Qi Yong-zhong Bao Zhi-ming Huang Zhi-xue Weng 《Colloid and polymer science》2008,286(2):233-241
Polyacrylate/silica nanocomposite latex particles were prepared by in situ emulsion polymerization of acrylate monomers initiated
by 2,2′-azobis(2-amidinopropane)dihydrochloride (AIBA) adsorbed by silica nanoparticles. The anchoring of polyacrylate (ACR)
onto silica nanoparticles was achieved through the physical absorption and chemical grafting reaction. The elution and HF
etching experiments showed that most silica nanoparticles were encapsulated by ACR to form the raspberry-like ACR/silica nanocomposite
latex particles. The silica nanoparticles with a greater grafting degree of ACR tended to locate in the bulk of the polymer,
and the silica particle with a lower grafting degree would not be combined with polymer latex particles and always remained
in water phase. The formation of the final ACR/silica nanocomposite latex particles included the anchoring of ACR onto silica
primary particles, aggregation of silica primary particles to form the silica-containing latex particles, and the growth of
latex particles. 相似文献
4.
Min Jiang Zhaohui Zheng Xiaobin Ding Xu Cheng Yuxing Peng 《Colloid and polymer science》2007,285(9):1049-1054
Novel fluorinated polyurethane hybrid latexes in the size range of 40–50 nm, fluoroalkyl acrylate as fluorinated monomers,
with various fluorine content (F% = 9∼26 wt%) were successfully prepared via emulsion polymerization process without traditional emulsifier. The waterborne
polyurethane, which was synthesized by using isophronediisocyanate, dimethylol propionic acid, polyethylene glycols, etc.,
served not only as copolymerizable macromonomer but also as polymeric high molecular weight emulsifier. The structures of
polyurethane macromonomer and fluorinated polyurethane were characterized by Fourier transform infrared and H1-NMR. Particle size, zeta potential, micromorphology of the latex par.ticles, and surface properties were investigated by
dynamic light scattering, potential particle size analyzer, transmission electron microscopy, and contact angle measurement,
respectively. Results illustrated that the advantage of this process is that the size of fluorinated polyurethane hybrid particle
is less sensitive to the composition. Furthermore, it was showed that fluorinated polyurethane latex particles had core-shell
structures, especially when the content of fluorine was 26.08 wt%. Moreover, there was an obvious migration of fluorinated
groups to the surface during the formation of fluorinated polymer films, although fluorinated groups were covered by polyurethane
in latex particles. 相似文献
5.
Anne‐Claire Le Meur Cyril Aymonier Valérie Heroguez 《Journal of polymer science. Part A, Polymer chemistry》2012,50(9):1746-1754
This article proposes the first report on the synthesis of nanometric crosslinked polynorbornene particles by ring‐opening metathesis polymerization in dispersion using ruthenium‐based complex (PCy3)2Cl2Ru?CHPh as initiator. Stable but raspberry‐shaped particles were obtained. In this study, a particular attention was paid to the influence of the crosslinker nature and addition mode on reaction kinetics and morphology of the latex particles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
6.
Incorporation of nonionic emulsifier inside methacrylic polymer particles in emulsion polymerization
The incorporations of polyoxyethylene lauryl ether (Emulgen 109P) and polyoxyethylene nonylphenyl ether (Emulgen 911) nonionic
emulsifiers inside poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), and poly(iso-butyl methacrylate) (Pi-BMA) particles prepared by emulsifier-present emulsion polymerizations were examined. To measure the amounts of the incorporated
nonionic emulsifiers, optimum compositions of 2-propanol aqueous solutions to remove the nonionic emulsifier from the particle
surfaces without removal from the insides were determined. The amount of the incorporation measured by gel permeation chromatography
was increased in the order of PMMA > PEMA > Pi-BMA, which accorded with the order of miscibility between each polymer and the emulsifier. 相似文献
7.
Michelle Prevot Christophe Déjugnat Helmuth M?hwald Gleb B Sukhorukov 《Chemphyschem》2006,7(12):2497-2502
Layer-by-layer assembled polyelectrolyte microcapsules are of great interest because they can possibly be used as microcontainers and they show interesting stimuli-responsive properties, which have been recently investigated. Here, we exploit capsules which are made temperature-sensitive by encapsulating poly(N-isopropylacrylamide) (PNIPAM). PNIPAM has a cloud point in water at about 32 degrees C, above which it collapses and is insoluble in water. Further this temperature responsiveness can be tuned by addition of various ions at various concentrations. Here, we present the encapsulation of PNIPAM inside polyelectrolyte microcapsules, and describe the dependence of the lower critical solution temperature (LCST) on the nature and the amount of different salts added. With this information, we demonstrate the ability to tune and finely control the collapse of encapsulated PNIPAM. In this light, this system could be used as a microsensor or drug- delivery system. 相似文献
8.
Shunchao Gu Tatsuro Sakamoto Yasuyuki Yamada Daisuke Nagao Mikio Konno 《Colloid and polymer science》2007,285(5):581-586
Single-stage polymerization recently proposed for producing micron-sized polymer particles in aqueous media by Gu, Inukai
and Konno (2002) was carried out under the control of agitation with styrene monomer, an amphoteric initiator, 2,2′-azobis
[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate and a pH buffer NH3/NH4Cl at a monomer concentration of 1.1 kmol/m3 H2O, an initiator concentration of 10 mol/m3 H2O and a buffer concentration of [NH3] = [NH4Cl] = 10 mol/m3 H2O. In the polymerizations, impeller speed was ranged from 300 to 500 rpm to satisfy complete dispersion of the monomer phase
and not to introduce the gas phase from the free surface. Polymerization experiments under steady agitation indicated that
impeller speed was an important factor for size distribution of polymer particles. An increase in impeller speed promoted
particle coagulation during the polymerization to enlarge the average size of polymer particles but widen the size distribution.
To produce polymer particles with narrow size distribution, stepwise reduction in impeller speed was examined in the polymerization
experiments. It was demonstrated that this method was more effective than the steady agitation. The impeller speed reduction
could produce highly monodisperse particles with an average size of 2 μm and a coefficient of variation of size distributions
of 2.2% that was much smaller than typical monodispersity criterion of 10%. 相似文献
9.
Two kinds of temperature-sensitive composite polymer particles were prepared by seeded emulsion copolymerizations of (dimethylamino)ethyl methacrylate and ethylene glycol dimethacrylate with 0.14 μm-sized polystyrene and 0.26 μm-sized poly(methylmethacrylate) seed particles. To evaluate the usefulness as a carrier for biomolecules, the enzymatic activities of trypsin adsorbed on these two composite polymer particles were measured at temperatures above and below each lower critical solution temperature (LCST). In both cases, adsorbed trypsin retained its enzymatic activity during repeated adsorption/desorption measurements. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 883–888, 1998 相似文献
10.
Baijun Liu Shicheng Sun Huixuan Zhang 《Journal of Dispersion Science and Technology》2017,38(8):1147-1153
Particle coagulation technology is a facile approach to prepare large-scale and narrowly dispersed polymer particles. However, diverse shapes such as ellipsolid, snowman, dumbbell, and trimer among others were obtained if the cross-linker was directly added into the initial reaction mixtures due to the restriction of the highly cross-linking particle fusion process. In this study, we prepared sub-200?nm, narrowly dispersed, highly cross-linked, and spherical latex particles using particle coagulation technology by controlling the relation between the cross-linking net formation and particle coagulation. Depending on the addition time or feeding rate of the cross-linker (divinylbenzene, DVB), the particles with different sizes or shapes were obtained. The later the addition start time of DVB, the narrower the particle size distribution of the latex particles. Alternatively, the increase of the continuing feeding time could also be used to decrease the width of particle size distribution of the ultimate latex. In addition, narrowly dispersed and spherical latex particles also could be directly obtained by advancing the particle coagulation time using 2, 2′-Azobis (2-methylpropionamidine) dihydrochloride as a cationic initiator. Our study presents a new method that will further widen the fields of application of particle coagulation technology. 相似文献
11.
Abraham Chemtob Valrie Hroguez Yves Gnanou 《Journal of polymer science. Part A, Polymer chemistry》2004,42(5):1154-1163
Latex particles based on 1,4‐polybutadiene were synthesized via dispersion ring‐opening metathesis copolymerization of 1,5‐cyclooctadiene with a α‐norbornenyl poly(ethylene oxide) macromonomer. Stable but polydisperse colloidal dispersions in the 50 nm to 10 μm size range were obtained. In this work, particular attention was paid to the effects of the kinetics of copolymerization on the structure of the graft copolymers formed and on the onset of turbidity. Strategies to prepare monodisperse polybutadiene particles were also designed through the growth of a polybutadiene shell from a well‐defined polynorbornene seed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1154–1163, 2004 相似文献
12.
Norma Negrete-Herrera Jean-Luc Putaux Elodie Bourgeat-Lami 《Progress in Solid State Chemistry》2006,34(2-4):121
We report the synthesis and characterization of polymer/Laponite nanocomposite latex particles through emulsion polymerization using organically modified Laponite clay platelets as seeds. Two approaches were adopted for the organic modification of Laponite. The first one is based on the grafting of either γ-methacryloyloxy propyl dimethyl-methoxysilane (γ-MPDES) or γ-methacryloyloxy propyl triethoxysilane (γ-MPTES) on the clay edges. The other strategy consists in exchanging the clay interlayer sodium ions by either a free radical initiator, 2,2-azobis(2-methyl propionamidine)hydrochloride (AIBA) or a cationic vinyl monomer, 2-(methacryloyloxy)ethyl trimethyl ammonium chloride (MADQUAT). The grafting was characterized both qualitatively using FTIR and quantitatively using elemental analysis or UV analysis. The results show that the degree of functionalization depends on the nature of the organic modifier. Before performing the emulsion polymerization reaction, the functionalized clay platelets were successfully dispersed in water. Nanocomposite latexes were then synthesized using a mixture of styrene (Styr) and butyl acrylate (BA) and sodium dodecyl sulphate (SDS) as anionic surfactant. An important result of the present work is that clay redispersion in water is a key step of the overall process. The larger the size of the clay aggregates, the poorer the stability of the resulting latex suspension. The morphology and mechanism of formation of the nanocomposite particles are discussed. 相似文献
13.
Yan Gao Sabrina Reischmann Johannes Huber Tobias Hanke Rudolf Bratschitsch Alfred Leitenstorfer Stefan Mecking 《Colloid and polymer science》2008,286(11):1329-1334
Single semiconductor quantum dots were embedded into polymer particles with diameters below 0.1 μm by an emulsion polymerization
procedure or via a secondary dispersion approach. The photoluminescence properties of the nanocrystals are retained upon encapsulation,
as demonstrated by fluorescence confocal microscopy.
相似文献
Stefan MeckingEmail: |
14.
Si‐Si Liu Zi‐Yi Yu Yuan Fang Su‐Na Yin Cai‐Feng Wang Li Chen Su Chen 《Journal of polymer science. Part A, Polymer chemistry》2011,49(14):3121-3128
In this work, a dually sensitive colloidal crystal (CC)‐loaded hydrogel has been synthesized via frontal polymerization (FP) in a facile and rapid way. First, a polystyrene CC film was fabricated by vertical deposition on the inner wall of a test tube. Then, a mixture of acrylic acid (AAc), 2‐hydroxyethyl methacrylate (HEMA), and glycerol along with the initiator and crosslinker was added to this test tube to carry out FP, resulting in the formation of CC‐loaded hydrogel. The influence of the mass ratios of HEMA/AAc on front velocity and temperatures were studied. The swelling behavior, the morphology, and the stimuli‐responsive behavior of the CC‐loaded hydrogels prepared via FP were thoroughly investigated on the basis of swelling measurement, scanning electron microscopy, and reflection spectra. Results show that the as‐prepared CC‐loaded hydrogels exhibit excellent dual sensitivity to both methanol concentrations and pH values with very short response time, which can be observed visually without the aid of instruments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
15.
16.
Hiroshi Kobayashi Toyoko Suzuki Mineho Moritaka Emi Miyanaga Masayoshi Okubo 《Colloid and polymer science》2009,287(3):251-257
Seeded emulsion polymerizations of styrene using polystyrene (PS) seed particles with incorporated nonionic emulsifier were
carried out at 40 and 70 °C to investigate the influence of temperature during the polymerization process including the swelling
step of the seed particles with monomer on the formation of multihollow PS particles. An increase in the temperature during
the polymerization process caused an increase in the rate of coalescence (i.e., the degree of coalescence at any given time)
of the small water domains in the inside. After the coalescence proceeded excessively, the water domains were eventually discharged
from the particles to the medium, resulting in nonhollow particles. The results show that it is important for the preparation
of the multihollow PS particles to control the coalescence of a lot of small water domains inside the seed particles with
the incorporated nonionic emulsifier, and strongly support the formation mechanism previously proposed.
Part CCCXX of the series “Studies on Suspension and Emulsion”. 相似文献
17.
A novel method to prepare organic/inorganic composite particles, i.e. poly(methyl methacrylate)/CaCO3/SiO2
three-component composite particles, using emulsion polymerization of methyl methacrylate with sodium lauryl sulfate as a surfactant in an aqueous medium was reported. CaCO3/SiO2
two-component inorganic composite particles were obtained firstly by the reaction between Na2CO3 and CaCl2 in porous silica (submicrometer size) aqueous sol and the specific surface area of the particles was measured by the Brunauer–Emmett–Teller (BET) method. The results show that the BET specific surface area of the CaCO3/SiO2
composite particle is much smaller than that of the silica particle, indicating that CaCO3 particles were adsorbed by porous silica and that two-component inorganic composite particles were formed. Before copolymerization with methyl methacrylate, the inorganic composite particles were coated with a modifying agent through covalent attachment. The chemical structures of the poly(methyl methacrylate)/CaCO3/SiO2
composite particles obtained were characterized by Fourier transform IR spectroscopy and thermogravimetric analysis. The results show that the surface of the modified inorganic particles is grafted by the methyl methacrylate molecules and that the grafting percentage is about 15.2%. 相似文献
18.
Preparation and properties of polytetrafluoroethylene-modified polyacrylate via emulsion polymerization 总被引:1,自引:0,他引:1
One method of preparation of polytetrafluoroethylene(PFTE)-modified polyacrylate emulsion has been studied. Through pre-emulsion technology, PTFE powder could be dispersed by high speed shearing with high-speed dispersor. PFTE-modified polyacrylate has been prepared by in situ copolymerization of n-butyl acrylate, n-methyl methacrylate, n-styrene, and α-methacrylic acid in the presence of seed particles of dispersed PTFE by semi-starved addition method. The properties of the emulsion under various polymerization conditions were investigated. The morphology of the latex particles with about 180 nm were observed by scanning electron microscopy (SEM). It was shown that the particles with linear PTFE/core–polyacrylate/shell could eventually be dispersed homogeneously. TG showed that the heat-stability was improved obviously. 相似文献
19.
20.
In this communication, a novel one-pot synthetic strategy for preparing hollow PNIPAM microspheres via an interfacial polymerization approach at the interface of an inverse W/O emulsion has been proposed and demonstrated. The results show that the prepared PNIPAM microspheres have real empty core and polymer shell structure, with a size range of 1-3 mum. The hollow microspheres experienced a reversible swelling and deswelling process by mediating the temperature below and above the lower critical solution temperature (LCST) of the PNIPAM. The new approach not only provided a unique technical pathway to prepare hollow PNIPAM microspheres in situ under mild reaction conditions but also opened a platform for helping to understand the mechanism of diffusion, migration of the PNIPAM at an oil/water interface above its LCST, and the polymer layer formation mechanism as well. 相似文献