首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The preparation of a star triblock copolymer based on polystyrene, poly(ethylene oxide), and poly(methacrylic acid) blocks (S-St-EO-MAA) is described. The polymer structure was achieved by the following route: the polystyrene macroanion (PSm) was formed first by a butyllithium-initiated polymerization of styrene and capping with Michler's ketone; the resulting N,N,N′,N′-tetramethyl-4,4′-diaminodiphenylmethanol (TDDM)-terminated polystyrene was further reacted with metal potassium. The oxo-anion initiated the ring-opening polymerization of ethylene oxide, and the desired ABC triblock copolymer was obtained by precipitation polymerization of methacrylic acid (MAA) initiated with a charge transfer complex (CTC) under UV irradiation using benzene as a solvent. The complex is composed of PS-b-PEO with a TDDM end group (PS-b-PEOtm) and benzophenone (BP).  相似文献   

2.
In this work, the poly(methacrylic acid‐coN‐isopropylacrylamide) thermosensitive composite hollow latex particles was synthesized by a three‐step reaction. The first step was to synthesize the poly(methyl methacrylate‐co‐methacrylic acid) (poly(MMA‐MAA)) copolymer latex particles by the method of soapless emulsion polymerization. The second step was to polymerize methacrylic acid (MAA), N‐isopropylacrylamide (NIPAAm), and N,N′‐methylenebisacrylamide in the presence of poly(MMA‐MAA) latex particles to form the linear poly(methyl methacrylate‐co‐methacrylic acid)/crosslinking poly(methacrylic acid‐coN‐isopropylacrylamide) (poly(MMA‐MAA)/poly(MAA‐NIPAAm)) core–shell latex particles. In the third step, the core–shell latex particles were heated in the presence of ammonia solution to form the crosslinking poly(MAA‐NIPAAm) thermosensitive hollow latex particles. The morphologies of poly(MMA‐MAA)/poly(MAA‐NIPAAm) core–shell latex particles and poly(MAA‐NIPAAm) hollow latex particles were observed. The influences of crosslinking agent and shell composition on the lower critical solution temperature of poly(MMA‐MAA)/poly(MAA‐NIPAAm) core–shell latex particles and poly(MAA‐NIPAAm) hollow latex particles were, respectively, studied. Besides, the poly(MAA‐NIPAAm) thermosensitive hollow latex particles were used as carriers to load with the model drug, caffeine. The effect of various variables on the amount of caffeine loading and the efficiency of caffeine release was investigated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5203–5214  相似文献   

3.
Methacrylic acid (MAA), methyl methacrylate (MMA), methacrylamide, and oligomers of MAA and MMA were selected as a model of active radical species in living template polymerization using stereocomplex formation. The adsorption behaviors of the aforementioned model compounds were examined toward porous isotactic‐(it‐) poly(methyl methacrylate) (PMMA) ultrathin films on a quartz crystal microbalance, which was prepared by the extracting of syndiotactic‐(st‐) poly(methacrylic acid) (PMAA) from it‐PMMA/st‐PMAA stereocomplexes. The apparent predominant adsorption of oligomers to monomers was observed in both PMAA and PMMA oligomers, suggesting that the mechanism of template polymerization follows the pick up mechanism. Although vinyl monomers were not incorporated into the porous it‐PMMA ultrathin film, both PMMA and PMAA oligomers were adsorbed at the initial stages. However, adsorbed amounts were limited to about 5 and 15% at 0.1 mol L?1, respectively, which are much smaller values than corresponding st‐polymers. The results imply that radical coupling reaction is prevented during template polymerization to support the resulting living polymerization. ATR‐IR spectral patterns of oligomer complexes and it‐PMMA slightly changed in both cases, suggesting complex formation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5879–5886, 2008  相似文献   

4.
In this work, the poly(methyl methacrylate‐co‐methacrylic acid)/poly(methacrylic acid‐co‐N‐isopropylacrylamide) thermosensitive composite semi‐hollow latex particles was synthesized by three processes. The first process was to synthesize the poly(methyl methacrylate‐co‐methacrylic acid) (poly (MMA‐MAA)) copolymer latex particles by the method of soapless emulsion polymerization. The second process was to polymerize methacrylic acid (MAA), N‐isopropylacrylamide (NIPAAm), and crosslinking agent, N,N′‐methylenebisacrylamide, in the presence of poly(MMA‐MAA) latex particles to form the linear poly(methyl methacrylate‐co‐methacrylic acid)/crosslinking poly(methacrylic acid‐co‐N‐isopropylacrylamide) (poly(MMA‐MAA)/poly(MAA‐NIPAAm)) core–shell latex particles with solid structure. In the third process, part of the linear poly(MMA‐MAA) core of core–shell latex particles was dissolved by ammonia to form the poly(MMA‐MAA)/poly(MAA‐NIPAAm) thermosensitive semi‐hollow latex particles. The morphologies of the semi‐hollow latex particles show that there is a hollow zone between the linear poly(MMA‐MAA) core and the crosslinked poly(MAA‐NIPAAm) shell. The crosslinking agent and shell composition significantly influenced the lower critical solution temperature of poly(MMA‐MAA)/poly(MAA‐NIPAAm) semi‐hollow latex particles. Besides, the poly(MMA‐MAA)/poly(MAA‐NIPAAm) thermosensitive semi‐hollow latex particles were used as carriers to load with the model drug, caffeine. The processes of caffeine loaded into the semi‐hollow latex particles appeared four situations, which was different from that of solid latex particles. In addition, the phenomenon of caffeine released from the semi‐hollow latex particles was obviously different from that of solid latex particles. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3441–3451  相似文献   

5.
Soap‐free poly(methyl methacrylate‐ethyl acrylate‐acrylic acid or methacrylic acid) [P(MMA‐EA‐AA or MAA)] particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and acrylic acid (AA) or methacrylic acid (MAA), and the influences of the mass ratio of core/shell monomers used in the two stages of polymerization ([C/S]w) and initiator amount on polymerization, particle size and its distribution were investigated by using different monomer addition modes. Results showed that when the batch swelling method was used, the monomer conversion was more than 96.0% and particle size distribution was narrow, and the particle size increased first and then remained almost unchanged at around 600 nm with the [C/S]w decreased. When the drop‐wise addition method was used, the monomer conversion decreased slightly with [C/S]w decreased, and large particles more than 750 nm in diameter can be obtained; with the initiator amount increased, the particle size decreased and the monomer conversion had a trend to increase; the particle size distribution was broader and the number of new particles was more in the AA system than in the MAA system; but the AA system was more stable than the MAA system at both low and high initiator amount. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

6.
A new diblock copolymer of isoprene (I) and methacrylic acid (MAA) was prepared by combination of an anionic mechanism with a charge transfer complex mechanism. In the first step, the polyisoprene (PI) macroanion formed by initiation with butyllithium was capped by p-dimethylaminobenzaldehyde (capped polyisoprene = PId); a dimeric coupling product was not detected. Then the binary system constituting of PId and benzophenone was used to initiate the polymerization of MAA under UV irradiation. The resulting diblock copolymer (PI-b-PMAA) was characterized by IR, NMR and gel permeation chromatography (GPC) in detail.  相似文献   

7.
In this work, an iron oxide (Fe3O4)/polystyrene (PS)/poly(N‐isopropylacryl amide‐co‐methacrylic acid) [P(NIPAAM–MAA)] thermosensitive magnetic composite latex was synthesized by the method of two‐stage emulsion polymerization. The Fe3O4 particles were prepared by a traditional coprecipitation method and then surface‐treated with either a PAA oligomer or lauric acid to form a stable ferrofluid. The first stage for the synthesis of the thermosensitive magnetic composite latex was to synthesize PS in the presence of a ferrofluid by emulsion polymerization to form Fe3O4/PS composite latex particles. Following the first stage of reaction, the second stage of polymerization was carried out with N‐isopropylacryl amide and methacrylic acid as monomers and with Fe3O4/PS latex as seeds. The Fe3O4/PS/[P(NIPAAM–MAA)] thermosensitive magnetic particles were thus obtained. The effects of the ferrofluids on the reaction kinetics, morphology, and particle size of the latex were discussed. A reaction mechanism was proposed in accordance with the morphology observation of the latex particles. The thermosensitive property of the thermosensitive magnetic composite latex was also studied. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3062–3072, 2007  相似文献   

8.
In this study, a novel molecularly imprinted polymer (MIP) based on methacrylic acid (MAA) monomer was synthesized to control release of trinitroglycerin (TNG) as a vasodilator drug for adjusting the cardiac conditions. For this purpose, TNG nanospheres based on poly(methacrylic acid) (PMAA) were prepared by using the precipitation polymerization process. The synthesized TNG nanospheres‐based MIP samples were characterized by means of Fourier transform infrared spectroscopy and field‐emission scanning electron microscopy in order to investigate their provided active functional groups within the cavities as well as morphology, respectively. The results showed that the appropriate non‐covalent bindings between the TNG (template) and PMAA provided within the MIP samples with imprinting factor of 1.98 were achieved by optimizing the amounts of trimethylolpropane trimethacrylate (TRIM) as a cross‐linker and MAA as a functional monomer. On the basis of these obtained conditions, the polymeric nanospheres containing TNG were formed in shape of spherical particles with an average diameter sizing about 40 nm. These remarkable results were obtained by the use of 1:10 molar ratio of TRIM/TNG and 1:6 molar ratio of MAA/TNG. Moreover, in‐vitro release of the TNG from the MIP samples to phosphate buffer solution (pH = 7.4) indicated that the MIP samples had a moderate and gradual release compared with the non‐imprinted polymer samples. These outcomes conducted us to consider the samples as carriers for adjusting potentially cardiac conditions. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

9.
The radical polymerization of methacrylic acid (MAA) at 0, 20, 40, and 70 °C was achieved in porous isotactic (it‐) poly(methyl methacrylate) (PMMA) films on quartz crystal microbalance (QCM) substrates, which were prepared by layer‐by‐layer assembled stereocomplex films of it‐PMMA and syndiotactic (st‐) poly(methacrylic acid) (PMAA), followed by the subsequent extraction of st‐PMAA. The MAA polymerization yields increased from 35 to 75%, as the polymerization temperature increased from 0 to 70 °C. Furthermore, infrared spectroscopy revealed that a higher polymerization temperature is necessary to form it‐PMMA/st‐PMAA stereocomplexes via stereoregular polymerization manner that resemble native it‐PMMA/st‐PMAA stereocomplexes. X‐ray diffraction pattern of porous it‐PMMA were also investigated for reaction fields. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3032–3036  相似文献   

10.
A carpetlike dense‐layer formation between a hydrophobic layer and a polyelectrolyte brush layer has been found in the monolayers of an ionic amphiphilic diblock copolymer, poly(1,1‐diethylsilacyclobutane)mblock‐poly(methacrylic acid)n, on a water surface by an X‐ray reflectivity technique. By detailed analysis, we have found that the hydrophilic layer under the water is not a simple layer but is divided into two layers, that is, a carpetlike dense methacrylic acid (MAA) layer near the hydrophobic layer and a polyelectrolyte brush layer. We have also confirmed that a well‐established polyelectrolyte brush is formed only for the m:n = 43:81 polymer monolayer: For m:n = 40:10 and m:n = 45:60 polymer monolayers, only a dense MAA layer is formed. This dense‐layer formation should be the origin of the interesting hydrophobic‐layer thickness variation previously reported; The hydrophobic‐layer thickness takes a minimum as a function of the hydrophilic chain length at any surface pressure studied. An overview of the data for three samples with different chain lengths (m:n = 40:10, 45:60, or 43:81) has shown that the thickness of this dense layer is 10–20 Å and is independent of the surface pressure and polymerization degree of poly(methacrylic acid) (PMAA) in the range studied. This dense‐layer formation is explained by the reasonable speculation that contact with PMAA is thermodynamically more stable than direct contact with water for the diethylsilacyclobutane (Et2SB) layer on water. In this sense, the dense layer acts like a carpet for the hydrophobic Et2SB layer, and a 10–20‐Å thickness could be a critical value for the carpet. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1921–1928, 2003  相似文献   

11.
《European Polymer Journal》2004,40(8):1683-1690
Multifunctional polymeric materials were obtained from poly(methacrylic acid-co-2-hydroxyethyl methacrylate), to be used as a raw material in the manufacture of contact lens and as drug delivery systems. Poly(methacrylic acid-co-2-hydroxyethyl methacrylate) was prepared by free-radical polymerization in aqueous solution at 60 °C using potassium persulfate (KPS) as initiator and N,N-methylenebisacrylamide (BIS) as cross-linker agent. The dynamic and equilibrium swelling properties of dry glassy poly(methacrylic acid-co-2-hydroxyethyl methacrylate) polymeric networks were studied as a function of pH and methacrylic acid (MAA) content. The water content increase as MAA content and pH increase. Timolol maleate delivery from poly(MAA) and poly(2-hydroxyethyl methacrylate) (HEMA) homopolymers was studied and the results show a Fickian diffusion behavior.  相似文献   

12.
Magnetic poly(methyl methacrylate) (PMMA)/poly(methyl methacrylate‐co‐methacrylic acid) [P(MMA–MAA)] composite polymer latices were synthesized by two‐stage soapless emulsion polymerization in the presence of magnetite (Fe3O4) ferrofluids. Different types and concentrations of fatty acids were reacted with the Fe3O4 particles, which were prepared by the coprecipitation of Fe(II) and Fe(III) salts to obtain stable Fe3O4 ferrofluids. The Fe3O4/polymer particles were monodisperse, and the composite polymer particle size was approximately 100 nm. The morphology of the magnetic composite polymer latex particles was a core–shell structure. The core was PMMA encapsulating Fe3O4 particles, and the shell was the P(MMA–MAA) copolymer. The carboxylic acid functional groups (COOH) of methacrylic acid (MAA) were mostly distributed on the surface of the composite polymer latex particles. Antibodies (anti‐human immunoglobulin G) were then chemically bound with COOH groups onto the surface of the magnetic core–shell composite latices through the medium of carbodiimide to form the antibody‐coated magnetic latices (magnetic immunolatices). The MAA shell composition of the composite latex could be adjusted to control the number of COOH groups and thus the number of antibody molecules on the magnetic composite latex particles. With a magnetic sorting device, the magnetic immunolatices derived from the magnetic PMMA/P(MMA–MAA) core–shell composite polymer latex performed well in cell‐separation experiments based on the antigen–antibody reaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1342–1356, 2005  相似文献   

13.
香豆素分子模板聚合物的合成与性能研究   总被引:2,自引:0,他引:2  
以香豆素为模板分子, α-甲基丙烯酸(MAA)、丙烯酰胺(MA)、2-乙烯基吡啶(2-VP)和4-乙烯基吡啶(4-VP)为功能单体, 二甲基丙烯酸乙二醇酯(EGDMA)为交联剂, 利用分子模板技术分别在甲苯、甲醇、氯仿和乙腈溶剂中合成了一系列香豆素分子模板聚合物(MTP), 研究了聚合体系组成对模板聚合物吸附特性的影响. 结果表明, 在所合成的模板聚合物中, 以MAA为功能单体, 乙腈为致孔溶剂, 以1∶4∶30的摩尔比加入模板分子、MAA及EGDMA时制备的模板聚合物吸附容量高、印迹效果和选择性好. 此模板聚合物有作为白芷样品中香豆素吸附分离材料的应用前景.  相似文献   

14.
Double‐shelled zirconia/titania (ZrO2/TiO2) hollow microspheres were prepared by the selective removal of the polymer components via the calcination of the corresponding tetra‐layer poly(N,N′‐methylenebisacryl amide‐co‐methacrylic acid) (P(MBA‐co‐MAA))/Zr(OH)4/poly(ethyleneglycol dimethacrylate‐co‐methacrylic acid) (P(EGDMA‐co‐MAA))/TiO2 hybrid microspheres. These tetra‐layer microspheres were synthesized by the combination of the distillation copolymerization of N,N(‐methylenebisacryl amide‐co‐methacrylic acid (MBA) or ethyleneglycol dimethacrylate (EGDMA) crosslinker and methacrylic acid (MAA) for the preparation of polymer core and third‐layer as well as the controlled sol‐gel hydrolysis of inorganic precursors for the construction of zirconium hydroxide (Zr(OH)4) and titania (TiO2) layers. The thicknesses of zirconia and titania shell‐layers were conveniently controlled via varying the feed of zirconium n‐butoxide (Zr(OBu)4) and titanium tetrabutoxide (TBOT) during the sol‐gel hydrolysis, while the sizes of polymer layers were tuned through a multi‐stage distillation precipitation copolymerization. The structure and morphology of the resultant microspheres were characterized by transmission electron microscopy (TEM), X‐ray diffractometer (XRD), X‐ray photoelectronic spectroscopy (XPS), and thermogrametric analysis (TGA).  相似文献   

15.
倪恨美 《高分子科学》2014,32(4):476-487
ATRP-template dispersion polymerization of methacrylic acid (MAA) on the template of polyvinyl pyrrolidone (PVP K-30) was carried out in the aqueous solution by using methyl 2-bromopropionate (MBP)/CuC1/2,2'-bipyridine (bpy) as the initiation system. The scanning electron microscopy (SEM), dynamic light scattering (DLS) and gel permeation chromatography (GPC) were employed for evaluating the results of polymerization. As a result, the minimonomer droplets formed due to the H-bond interaction of PVP-MAA. The stability of droplets was dependent on pH and the concentrations of both PVP and MAA. When pH 〈 2, the coagulum of PVP-MAA formed, whereas when pH 〉 4.5, the droplets were not observable by DLS. In order to prepare the stable latex, the concentration of PVP should be lower than 9 wt%, whilst the concentration of MAA should be lower than 5.5 wt%. The optimum condition was pH 2.4, PVP 4.76 wt% and MAA 5 wt%, by which the stable latex of ca. 50 nm nanoparticles of PMAA/PVP was prepared by ATRP polymerization and simultaneously the molar mass of PVP was duplicated by PMAA according to GPC diagrams. In contrast, by using AIBN, KPS and KPS-Na2SO3 redox initiation system, the coagulum accompanying with the larger molar mass of PMAA was obtained, irrespective of pH and concentrations of PVP and MAA.  相似文献   

16.
In this research, the synthesis and properties of thermally responsive complex polymer networks containing Fe3O4 nanoparticles were studied. First, a stable ferrofluid containing Fe3O4 nanoparticles was synthesized via a coprecipitation method in the presence of a poly(acrylic acid) oligomer. This stable ferrofluid could mix well with water‐soluble monomers by the adjustment of its pH value. Second, a thermally responsive copolymer was synthesized in the presence of the ferrofluid containing Fe3O4 nanoparticles to obtain the complex polymer networks. By the adjustment of the pH value, the ferrofluid could remain stable in the polymerization system, in which N‐isopropylacrylamide (NIPAAm) and methacrylic acid (MAA) were used as comonomers to provide thermoresponsive properties and acid groups and ammonium persulfate and sodium metabisulfite were used as the redox initiator system. Several variables, such as the molar ratio of MAA to NIPAAm, the concentrations of the monomers and crosslinking agent, the addition of an ammonium solution, and the content of the ferrofluid, were studied in this polymerization. Their effects on the morphology, structure, polymerization rate, and thermal properties of the complex polymer networks were discussed. The swelling and thermoresponsive behaviors of the complex polymer networks containing Fe3O4 nanoparticles were also studied, and the composition–morphology–property relationship was established. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5923–5934, 2005  相似文献   

17.
An interpolymer complex was prepared by mixing aqueous solutions of poly(ethylene oxide) (PEO) and of a poly(carboxylic acid), i.e., poly(acrylic acid)(PAA), poly(methacrylic acid)(PMAA), or styrene-maleic acid copolymer(PSMA). The complexation mechanism was discussed on the basis of results of such experimental methods as viscosity, potentiometric titration, and turbidimetry. The hydrogen bond is primarily involved in these complexations, but the influence of hydrophobic interaction on complexation can not be ignored. If the degree of dissociation α of carboxylic acid or the degree of polymerization Pn of PEO was perceptibly changed, a stable complex was obtained at about α 0.1 or Pn (PEO) = 40 for PMAA, 200 for PAA. This fact indicates that more than a definite number of binding sites are necessary for a stable interpolymer complex to be formed and that cooperative interaction among active sites plays an important role in complex formation.  相似文献   

18.
The kinetics and mechanism of polymerization of methacrylic acid (MAA) and ethyl acrylate (EA) initiated by the redox system, Mn3+–thiodiglycolic acid (TDGA) were investigated in the 15–35°C temperature range. The polymerization kinetics of both the monomers followed the same mechanism, viz., initiation by primary radical and termination by Mn3+–thiodiglycolic acid complex. The rate coefficients ki/k0 and kp/kt were related to the monomer reactivity and polymer radical reactivity, respectively. It was observed that both monomer reactivity and polymer radical reactivity followed the same order, viz., EA > MAA. The polymer radical reactivity varied inversely with the Q values of the monomers.  相似文献   

19.
The boronic acid‐functionalized core–shell polymer nanoparticles, poly(N,N‐methylenebisacrylamide‐co‐methacrylic acid)@4‐vinylphenylboronic acid (poly(MBA‐co‐MAA)@VPBA), were successfully synthesized for enriching glycosylated peptides. Such nanoparticles were composed of a hydrophilic polymer core prepared by distillation precipitation polymerization (DPP) and a boronic acid‐functionalized shell designed for capturing glycopeptides. Owing to the relatively large amount of residual vinyl groups introduced by DPP on the core surface, the VPBA monomer was coated with high efficiency, working as the shell. Moreover, the overall polymerization route, especially the use of DPP, made the synthesis of nanoparticles facile and time‐saving. With the poly(MBA‐co‐MAA)@VPBA nanoparticles, 18 glycopeptides from horseradish peroxidase (HRP) digest were captured and identified by MALDI‐TOF mass spectrometric analysis, relative to eight glycopeptides enriched by using commercially available meta‐aminophenylboronic acid agarose under the same conditions. When the concentration of the HRP digest was decreased to as low as 5 nmol, glycopeptides could still be selectively isolated by the prepared nanoparticles. Our results demonstrated that the synthetic poly(MBA‐co‐MAA)@VPBA nanoparticles might be a promising selective enrichment material for glycoproteome analysis.  相似文献   

20.
An amphiphilic block copolymer of silacyclobutane and methacrylic acid (MAA) was synthesized via a living anionic polymerization of 1,1‐diethylsilacylcobutane (EtSB). Sequential addition of 1,1‐diphenylethylene and t‐butyl methacrylate (tBMA) to living poly(EtSB) in the presence of lithium chloride gave poly(EtSB‐blocktBMA) with narrow molecular weight distributions. The t‐butyl ester groups in the obtained polymer were readily hydrolyzed via heating in 1,4‐dioxane in the presence of concentrated aqueous hydrochloric acid. The block copolymer with a short MAA segment was soluble in chloroform and insoluble in methanol and basic water, whereas the block copolymer with a long MAA segment was soluble in methanol and basic water and insoluble in chloroform. The block polymer (EtSB/tBMA = 45/60) formed a monolayer film on the water surface; this was confirmed by surface pressure measurement. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 86–92, 2001  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号