共查询到20条相似文献,搜索用时 31 毫秒
1.
交联度对原位聚合法制备聚合物胶束性质的影响及相应的空心球制备 总被引:2,自引:0,他引:2
用原位聚合法成功地制备出不同响应温度的温敏性聚乳酸/聚(异丙基丙烯酰胺-co-丙烯酰胺)[P(D,L-LA)/P(NIPAM-co-AM)]核壳胶束. 实验中发现, 壳层的交联剂含量对粒子的尺寸有很大的影响, 当交联剂的摩尔分数从5%提高到15%时, 粒子在25 ℃时的流体力学直径从170.2 nm增加到886.5 nm. 通过对胶束粒子的核进行生物降解, 方便地得到了相应的空心球. 用FTIR监测核的降解过程, 用SEM和AFM检测核降解完全后粒子的外在形貌和内在结构变化. DLS结果表明, 空心球粒子同样具有良好的温度响应性, 其响应温度可通过改变原位聚合时单体AM的含量加以调节. 相似文献
2.
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
3.
Li-qin Cao Liu-ping Chen Ji-qing Jiao Shu-ying Zhang Wei Gao 《Colloid and polymer science》2007,285(11):1229-1236
Herein, we report a new method that has been developed to prepare thermoresponsive polymers. The white, dry, fine powders
were obtained directly from cross-linking polymerization of N-isopropylacrylamide in supercritical carbon dioxide (scCO2) with N,N-methylenebisacrylamide as a cross-linker. The effects of the reaction pressure and time as well as the initial concentrations
of the initiator, cross-linker, and monomer on the yield and morphology of the resulting polymer were investigated systematically.
The polymer yield was increased with the concentrations of the cross-linker, monomer, and reaction time. Under the condition
of using higher cross-linker concentrations, the cross-linked poly (N-isopropylacrylamide) microparticles with diameters of 50 nm were generated in scCO2 in high-yield and short reaction times. These results suggest that the synthetic method using scCO2 can be used to prepare biomedical materials such as the controlled drug-release system. 相似文献
4.
The structure of the opaque poly(acrylamide) gels is studied by using a confocal laser scanning microscope. The polymer network of the gel consists of the fractal aggregate of the colloidal particles in the higher concentration region of the cross-linker. The diameter of the colloidal particle, which formed in the gel, increases from 180 to 420 nm with an increase of the concentration of cross-linker. On the other hand, the fractal dimensions of the aggregate remain constant, ranging from 1.5 to 1.7. The densities of the particle are calculated to be 0.7 and 1.2 x 103 kg/m3, which are >10 times larger than the average density of the polymer network of the gel. The results indicate that the monomer and the cross-linker are densely cross-linked into the particles. 相似文献
5.
Judit Éva Fleischer Radu Levente Novak John F. Hartmann Neda Beheshti Anna-Lena Kjøniksen Bo Nyström János Borbély 《Colloid and polymer science》2008,286(4):365-376
This work describes the formation of water-soluble hydrophilic nanoparticles from biosynthetic poly-γ-glutamic acid (PGA).
Nanoparticles were formed by cross-linking using 2,2′-(ethylenedioxy) diethylamine in the presence of water-soluble carbodiimide.
The structure was determined by nuclear magnetic resonance spectroscopy and the particle size by transmission electron microscopy
(TEM), size exclusion chromatography (SEC), and dynamic light-scattering (DLS) measurements. The results from TEM, SEC, and
DLS reveal that the particle size depends on the ratio of cross-linking. Particle size values measured by TEM were between
20 and 90 nm. Formation of cross-linked nanoparticles results in a dramatic viscosity drop compared to the viscosity of the
corresponding solution of the parent PGA. The viscosity and DLS experiments disclose an intriguing interplay between intrachain
and interchain cross-linking of the polymer chains, depending on the cross-linker density and polymer concentration. The SEC
measurements show that the retention time of the major portion of particles increase because of the higher cross-linking ratio.
At moderate cross-linker concentration, intramolecular cross-linking is the dominant process, whereas at higher cross-linker
densities, the interpolymer cross-linking plays an important role. As a result, large clusters are also formed. 相似文献
6.
碳纳米管表面绿原酸印迹固相萃取材料的制备及应用 总被引:2,自引:1,他引:1
在多壁碳纳米管表面接枝的双键键合,以绿原酸为模板,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,采用沉淀聚合技术,在碳纳米管表面成功制备绿原酸印迹材料.采用红外光谱、扫描电镜和热重分析研究此印迹材料的性能.结果表明,在碳纳米管表面接枝一层稳定、均匀、30~40 nm厚的印迹材料.采用高效液相色谱研究此印迹材料的吸附动力学及吸附容量,实验结果表明,此印迹材料对绿原酸的结合存在两个结合位点,最大吸附容量Qmax分别为21.5和32.7 μmol/g.以此印迹材料作为固相萃取剂,优化萃取条件,成功应用于金银花提取液中绿原酸的富集分离研究,富集因子达25. 相似文献
7.
Among the solid-phase extraction (SPE) techniques, a novel system for a triazine herbicide named ametryn, has been developed based on a molecular imprinted polymer (MIP) phase. Through this method, the synthesis of the complementary to ametryn MIP was accomplished and the factors influencing its efficiency have been optimized. Through the optimization process, the type and the amounts of functional monomer and solvents, template amount, cross-linker, initiator as well as the polymerization temperature were considered to be evaluated. Based on the obtained results, the optimum conditions for the efficient polymerized sorbent, considering the recovery efficiency were solvent: acetonitrile, 6.41 mL; monomer: methacrylic acid, 5.41 mmol; template: 1.204 mmol; cross-linker: 27.070 mmol; initiator: 2.03 mmol; temperature: 40.86 degrees C. The optimum molar ratio among the template, monomer and cross-linker for ametryn was 1:4.49:22.48. The reversed-phase HPLC-UV was used for the ametryn determination, using an isocratic solvent delivery system (acetonitrile: H(2)O, 60:40), flow-rate of 0.8 mL min(-1) and a UV wavelength of 220 nm. In line with the obtained results, using central composite design (CCD) can increase the precision and accuracy of synthesis and optimization of MIP to ametryn and possibly other similar analogues. 相似文献
8.
Alejandro Lapresta-Fernández Piotr J. Cywinski Artur J. Moro Gerhard J. Mohr 《Analytical and bioanalytical chemistry》2009,395(6):1821-1830
We present the synthesis of fluorescent acrylamide nanoparticles (FANs) capable of recognizing non-steroidal anti-inflammatory
drugs (NSAIDs) in buffered aqueous solutions. Within this important group, we selected naproxen, one of the 2-arylpropionic
acids (profens), due to its use for the treatment of moderate pain, fever, and inflammation. The nanosensors were prepared
under mild conditions of inverse microemulsion polymerization using aqueous acrylamide as the monomer and N,N′-methylenebisacrylamide as the cross-linker, employing the surfactants polyoxyethylene-4-lauryl ether (Brij?30) and sodium
bis(2-ethylhexyl)sulfosuccinate in hexane. Furthermore, a fluorescent monomer, (E)-4-[4-(dimethylamino)styryl]-1-[4-(methacryloyloxymethyl)benzyl]pyridinium chloride (mDMASP) has been synthesized and incorporated
into the nanoparticles. The nanosensors exhibit a broad absorbance at around 460 nm and a structureless fluorescence band
with maximum at 590 nm in 0.5 M phosphate buffer (pH = 7.2). The recognition process is performed on the basis of ionic interactions
which are monitored by the fluorescence increase at 590 nm upon addition of different concentrations of naproxen. The FANs
show a size distribution in the range of 20–80 nm, with a hydrodynamic diameter of 34 nm. In order to assess the selectivity
of the FANs, a systematic study was conducted on the effect produced by drugs and biomolecules that could interfere with the
analysis of naproxen. 相似文献
9.
Blanca Madrigal González 《Analytica chimica acta》2005,528(2):219-228
A holographic sensor for real-time detection of divalent metal ions (Ca2+, Mg2+, Ni2+, Co2+ and Zn2+) has been fabricated by incorporating a chelating monomer into a hydrogel matrix. A methacrylated analogue of iminodiacetic acid (IDA) was prepared and co-polymerised with hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EDMA) as a cross-linker to form polymer films. A silver-based reflection hologram was incorporated into the hydrogel by diffusion followed by holographic recording using a frequency-doubled Nd/YAG laser. Changes in the replay wavelength of the hologram were used to characterise the swelling behaviour of the matrix as a function of its chemical composition and concentration of analyte in the media. The effects of active monomer, cross-linker, pH and ionic strength on the swelling of the matrix and on metal detection sensitivity have been studied. Polymers containing >10 mol% of chelating monomer and 6 mol% of cross-linker showed significant responses (46.3 nm) within 30 s at an ion concentration of 0-40 nm. The selectivity of the holograms towards the different ions tested was Ni2+>Zn2+>Co2+>Ca2+>Mg2+. The sensor showed fully reversible responses, permitting real-time monitoring of calcium ion efflux during the germination of Bacillus megaterium spores. 相似文献
10.
以羧基化的多壁碳纳米管(MWCNT)为基底,通过酰胺化表面接枝聚乙烯亚胺(PEI)得到MWCNT-PEI复合物功能单体,进而以没食子酸丙酯(PG)为模板分子、乙二醇二缩水甘油醚为交联剂,制备了PG表面分子印迹聚合物,最后采用滴涂法在玻碳电极(GCE)表面构建PG分子印迹电化学传感器。通过循环伏安、电化学阻抗和差分脉冲伏安等手段对所构建传感器的导电性以及PG分子的线性响应、特异识别性、检测稳定性和重复性等进行了测试与表征。结果表明,传感器在PG浓度为1×10~(-8)~1×10~(-5)mol/L的范围内具有良好的线性关系,相关系数为0. 9964,检出限达2. 5×10~(-9)mol/L。此外,该传感器在实际样品中的PG回收率为95%~98%。 相似文献
11.
12.
Colloidal Au/Ag multilayer films were prepared by alternate assembly of Au nanoparticles with a size of 5 +/- 1.2 nm and Ag nanoparticles with a size of 10 +/- 2.4 nm by using 1,5-pentanedithiol as cross-linker. Nanoporous gold films with a ligament size of 26.7 +/- 4.6 nm were then prepared by selective dissolution of sacrificial templates of silver particles in colloidal Au/Ag multilayers. The complete dissolution of Ag particles in colloidal Au/Ag multilayers in a mixture solution of 3.0 mM HAuCl(4) and 3 M NaCl took place at room temperature without damage of the colloidal Au film. This method to prepare nanoporous gold films was further extended to the preparation of nanoporous gold nanotubes by depositing colloidal Au/Ag film on the inner wall of anodic aluminum oxides (AAO) followed by dissolution of colloidal Ag and removal of AAO templates. 相似文献
13.
Surface grafting of a polymerizable monomer onto Au was used to produce nanometer-scale planar hydrogel films with controllable volume. A self-assembled monolayer of 11-mercaptoundecanoic acid on a planar Au surface was activated through water-soluble carbodiimide and N-hyroxysuccinimide followed by reaction with 2-aminomethacrylate to produce a methacrylate-terminated surface layer, which readily polymerized under UV radiation in the presence of hydroxyethyl methacrylate monomer, ethylene glycol dimethacrylate cross-linker, and a photoinitiator. The reaction steps were characterized by external reflection mode Fourier transform IR spectroscopy. Under controlled UV exposure, thin (3 nm < d < 10 nm) hydrogel films were obtained from 1:1 ethanol/H(2)O. Surface plasmon resonance measurements were used to characterize both the synthesis of the hydrogel and the potential-induced volume changes. The nanometer-scale hydrogels thus produced undergo reproducible changes in thickness, when a potential is applied across the film. Thickness changes increasing with applied potential were obtained for both voltages in the range |V(appl)| = 600 mV. In NaCl, electrolyte films swell with application of negative potentials and shrink with positive potentials, due to the imbibing or extrusion of hydrated Na(+) ions, respectively. Thickness changes as large as 50% can be achieved. An increase in the cross-linker content results in thicker films, but at the cost of dramatically restricted swelling. Response times are generally faster for smaller applied potentials, as expected if the volume change results from mass transport of electrolyte. 相似文献
14.
From discrete particles to spherical aggregates: a simple approach to the self-assembly of Au colloids 总被引:1,自引:0,他引:1
Zhong Z Subramanian AS Highfield J Carpenter K Gedanken A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(5):1473-1478
Here we demonstrate a simple, template-free approach to the formation of spherical gold aggregates through the reduction of HAuCl4 by NaBH4, in the presence of cysteine (Cys) as a capping agent. The resulting aggregates are quite stable in solution. The pH of the solution and the molar ratio of Au:Cys are two key empirical factors in the formation of such highly ordered aggregates. At slightly alkaline pH (7-10) and with Au:Cys ratios ranging from 1:0.5 to 1:2, spherical Au aggregates of 30-80 nm are formed. At lower Cys ratios (Au:Cys> or =1:0.5) very loosely linked aggregates are formed; however, at very high Cys ratios (Au:Cys< or =1:3), highly dispersed Au particles of 2-4 nm are obtained, which are virtually indistinguishable from the original colloidal form. Aggregate size is influenced markedly by component concentration; a 3-fold increase in standard levels resulted in Au spherical aggregates of a larger size, 200-500 nm. In addition, we used a combination of Cys and lysine (Lys) as a capping agent/cross-linker and found that the morphology of the Au colloid aggregates can be easily manipulated from a linear to a spherical form by adjusting the proportions of Cys and Lys in the capping agent/cross-linker mixture. The introduction of mercapto (SH)-containing organic acids reduced the cross-linking ability of Cys, especially in the case of long-chain acids. Complete disruption of the spherical aggregates highlights the importance of Cys per se. An explanation of this ordered self-assembly process is proposed, in the context of the known surface chemistry of Au colloids. 相似文献
15.
16.
The use of particle formulations with antifouling surface properties attracts increasing interest in several biotechnological applications. Majority of these studies utilize a poly(ethylene glycol) coating to render the corresponding surface nonrecognizable to biological macromolecules. Herein, we report a simple way to prepare novel antifouling colloids composed of oligo(ethylene glycol) backbones via surfactant-free emulsion polymerization. Monodisperse cross-linked poly(ethylene glycol) ethyl ether methacrylate particles were characterized by dynamic light scattering and transmission electron microscopy. The effects of monomer, cross-linker and initiator on particle characteristics were investigated. More importantly, a prominent blockage of bovine serum albumin adsorption was obtained for the poly(ethylene glycol)-based sub-micron (~200 nm) particles when compared with similar-sized poly(methyl methacrylate) counterparts. 相似文献
17.
Effects of solution pH on the physical properties of a semidilute aqueous alginate solution without cross-linker agent and during gelation via the Ugi multicomponent condensation reaction at a fixed cross-linker concentration have been investigated. Both rheology and turbidity results on the alginate solution without cross-linker revealed enhanced associations at low pH. In the course of the cross-linker reaction, the time of gelation is shortest at pH = 3.5 and at pH values above 3.8 no gel is formed but only a viscosification of the solution is observed. The turbidity during the cross-linking reaction rises as the pH increases from 3.5 to 5. Furthermore, the initial change of the turbidity in the course of the cross-linking process is more pronounced at higher pH. The dynamic light scattering (DLS) results of the reaction mixture at pH = 4.0 (ergodic features at this condition) show that the chain relaxation is slowed down as the reaction proceeds. The effect of pH on the kinetics of the Ugi reaction is discussed. 相似文献
18.
侧链型偶氮聚合物液晶在不同波长激发条件下的光致取向 总被引:4,自引:0,他引:4
合成了聚甲基丙烯酸 (6 [4 (4 氰基偶氮苯 )苯氧基 ]己酯 ) (Poly(6 [4 (4 cyanophenylazo)phenoxy]hexylmethacrylate) (PM6ABCN) ) ,采用溶液挥发法在玻璃载片上成膜 ,研究了薄膜样品在Tg 温度以下的光致取向 .用波长分别为 36 6、40 0和 436nm的偏振光照射 ,发现PM6ABCN薄膜的光致取向过程不仅依赖于光的强度 ,还依赖所使用的偏振光的波长 .在低于Tg 的温度下 ,用波长为 40 0nm ,功率为 2 0mW cm2 的光照射 10 0s可以使样品的取向达到饱和 ,而用 36 6nm的光导致的取向程度要小于 40 0nm和 436nm的光 ,因为 36 6nm的光会在稳态时产生更多数目的cis异构体 相似文献
19.
Yueqin Yu Yanshun Li Chunjing Zhu Lingxiu Liu 《Central European Journal of Chemistry》2010,8(2):426-433
Based on a biodegradable cross-linker, N-maleyl chitosan (N-MACH), a series of Poly(N-isopropylacrylamide) (PNIPAAm) and Poly(N-isopropylacrylamide-co-acrylamide) [P(NIPAAm-co-Am)] hydrogels were prepared, and their lower critical solution temperature
(LCST), swelling kinetics, equilibrium swelling ratio in NaCl solution, and enzymatic degradation behavior in simulated gastric
fluids (SGF) were discussed. The LCST did not change with different cross-linker contents. By altering the NIPAAm/Am molar
ratio of P(NIPAAm-co-Am) hydrogels, the LCST could be increased to 39°C. The LCST of the hydrogel was significantly influenced
by the monomer ratio of the NIPAAm/Am but not by the cross-linker content. In the swelling kinetics, all the dry hydrogels
exhibited fast swelling behavior, and the swelling ratios were influenced by the cross-linker content and NIPAAm/Am molar
ratios. Equilibrium swelling ratio of all the hydrogels decreased with increasing NaCl solution concentration. In enzymatic
degradation tests, the weight loss of hydrogels was dependent on the cross-linker contents and the enzyme concentration.
相似文献
20.
Wei-jun Ye Jason S. Keiper Joseph M. DeSimone 《高分子科学》2006,(1):95-101
Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant (bis-[2-(F-hexyl)ethyl]phosphate sodium), water-soluble/CO2-insoluble acryloxyethyltrimethyl ammonium chloride monomer and N,N'-methylene-bisacrylamide cross-linker were solubilized into CO2 continuous phase via the formation of water-in-CO2 (w/c) microemulsion water pools. Initiated by a CO2-soluble initiator, 2,2'-azo-bisisobutyronitrile (AIBN), cross-linked poly(acryloxyethyltrimethyl ammonium chloride) particles were produced and stabilized in these w/c internal water pools. Nano-sized particles with sizes less than 20 nm in diameter and narrow particle size distributions were obtained. 相似文献