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本文以St/DVB凝胶、St/DVB超髙交联凝胶为参比网络结构,用荧光光谱方法跟踪研究了St/DVB交联凝胶氯甲基化反应过程中网络结构形态的衍变.发现随着凝胶中氯百分含量的增加,其苯基激基缔合物320nm荧光谱带趋于消失;在最初反应阶段.苯基多环聚集体420nm荧光谱带强度迅速上升.而后急剧下降,同时在488nm左右出现一新的荧光谱带,与超高交链凝胶荧光谱带相近似:红外光谱证实了氯甲基化凝胶中亚甲基交联桥的增加.结果表明,伴随氯甲基化反应发生的后交联反应可使交联凝胶疏松网络区结构趋向紧密,使溶剂难以逾渗的微凝胶核松弛解体,从而使St/DVB交联凝胶网络涨落趋向均匀. 相似文献
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The morphological change of St/DVB crosslinked gels during chloromethylation wasstudied by fluorescence spectroscopy using St/DVB crosslinked and hypercrosslinked gels as controlsamples. It has been found that with increase of chlorine content, the excimer emission band (~325nm)approaches to vanish, while the intensity of multi-ring aggregate emission band (~420nm) quicklyreaches a maximum, and then decreases sharply accompanied by appearance ofa new broad bandcentred at ca 488nm which roughly coincides with the typical emission band of hypercrossllinkedSt/DVB gels. Mearwhile, the result of IR measurement suggests that methylene bridge between phenylrings forms and increases with chloromethylation process. These results are explained in terms ofaside reaction of post-crosslinking, which densifies the loosely crosslinked networks and undoes thedensely entangled microgel nuclei. As a result, the morphology of the crosslinked gels becom es morehomogeneous with chloromethylation. 相似文献
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The photophysical properties of a series of pyrene-labelled styrene/divinyl benzene (St/ DVB) copolymers have been studied for the first time by steady-state fluorescence spectra. The results indicate that when pyrenyl content (mol%) in the copolymer is lower than 0. 006% , the fluorescence spectra only show the pyrenyl monomer emission, while the 0-0 transition band is much suppressed and the vibronic structure is partially lost. However, in the fluorescence spectra of the copolymers with pyrenyl content higher than 0.3%, there appear some new emission bands at ca 420 nm, 440 nm and 475 nm. These results are explained in terms of the formation of ground-state and excited-state aggregates, which reveals the heterogeneity of the crosslinked networks. 相似文献
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Morphological investigations of crosslinked polystyrene microspheres by seeded polymerization 总被引:1,自引:0,他引:1
Crosslinked polystyrene microspheres with novel surface and inner morphologies were synthesized by seeded polymerization
following a seed-swelling method, using uncrosslinked polystyrene microspheres as seeds and a mixture of toluene, styrene
(St), and divinylbenzene (DVB) as the swelling agent. With the increasing toluene/ (St+DVB) ratio, the crosslinked particles
changed from smooth-surfaced spheres to deformed spheres with dimples or heavy dents at the surface. A single hole inside
the spherical particles was produced at low St/DVB ratio, while higher St/DVB ratios gave irregular dented or dimpled particles.
Ultrathin cross-section observation by TEM revealed a non-uniformly crosslinked inner structure.
Received: 20 January 1998 Accepted: 14 April 1998 相似文献
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在Lewis酸催化剂存在下,1,4-二氯甲氧基丁烷对冠醚二苯并-18-冠-6(1)进行氯甲基化修饰使其转变成氯甲基化冠醚(2),其结构经1HNMR,13C NMR,IR及MS表征。2与交联聚乙烯醇(CPVA)微球表面的羟基发生亲核取代反应实现冠醚的固载化,制得固载有冠醚的功能微球(3)。实验结果表明,1的氯甲基化反应易于进行,在两个苯环上分别发生了对称的氯甲基化反应,2为对称的四取代产物。通过2的氯甲基与CPVA的羟基之间的亲核取代反应,1可容易地化学固载到CPVA表面。 相似文献
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Haifeng Gao Yiqiang Zhao Shoukuan Fu Bin Li Minqian Li 《Colloid and polymer science》2002,280(7):653-660
A new type of narrowly dispersed fluorescent crosslinked polystyrene (PS) nanoparticles (20-50 nm) was synthesized via a modified microemulsion copolymerization of styrene, crosslinker divinyl benzene (DVB) and a hydrophilic comonomer amino ethyl methacrylate hydrochloride (AEMH), in the presence of pyrene. Characterized by steady-state fluorescence spectra, these nanoparticles show high luminescent intensity and the embedded pyrene has a negligible desorption from the nanoparticles. The emission intensity I1 of the pyrene in the crosslinked nanoparticles is 40 times higher than that of pyrene in toluene or styrene solution with the same concentration. The fluorescence emission intensity can be varied by the amount of the monomer, crosslinker and pyrene, but is influenced little by the amount of AEMH in the range of investigation. The surface of the nanoparticles is modified by amino and amidino functional groups introduced by the comonomer and the initiator 2, 2'-azobis(2-amidinopropane) dihydrochloride (V50), which controls the zeta potential on the particle surface. 相似文献
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Ecaterina Stela Dragan Ecaterina Avram Damian Axente Cristina Marcu 《Journal of polymer science. Part A, Polymer chemistry》2004,42(10):2451-2461
The synthesis and characterization of a series of macroporous, strong basic anion exchangers (SBAEs), with an average pore radius higher than 50 nm, and the evaluation of their sorption properties for uranyl chlorocomplexes from HCl solutions are reported. Finely divided macroporous styrene–divinylbenzene (S–DVB) copolymers with a narrow distribution of beads sizes, diameters within the range of 90–200 μm, were prepared for this purpose with 2‐ethyl‐1‐hexanol as a porogen, at a high dilution of monomers (D ≥ 0.55 mL/mL). Chloromethyl groups were introduced with (CH2O)n/Me3SiCl as a chloromethylation agent in the presence of a Lewis acid as a catalyst (TiCl4, SnCl4, and FeCl3) in CHCl3 as a reaction medium. SnCl4 and FeCl3 gave comparable chloromethylation degrees in the same reaction conditions. TiCl4 was not efficient as a catalyst in the chloromethylation with this reagent. Diethyl‐2‐hydroxyethylamine was used as a tertiary amine to prepare SBAEs. Structural and morphological characteristics were determined after every functionalization step of the macroporous network. Both the chloromethylation, in the presence of FeCl3 as a catalyst, and the amination reactions determined a significant decrease of the pore volume, in the whole range of the nominal crosslinking degree, comparative with the starting copolymer. The specific surface area and the average pore radius varied in a different way as a function of the nominal crosslinking degree. Thus, the specific surface area increased and the average pore radius decreased after chloromethylation and amination for copolymers with a DVB content lower than 10 wt %. Small decreases of the specific surface area and the average pore radius were observed after chloromethylation and amination reactions for copolymers with a DVB content higher than 10 wt %. SBAEs were also characterized by thermogravimetric analysis and sorption capacity for uranyl chlorocomplexes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2451–2461, 2004 相似文献
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具有核壳结构磁性复合微球的制备与表征 总被引:2,自引:0,他引:2
采用两步法制备了具有核壳结构的Fe3O4/P(MMA/DVB)(core)-P(St/GMA/DVB)(shell)磁性复合微球.首先,用改进的细乳液聚合制备了Fe3O4/P(MMA/DVB)微球;然后,加入总量不同的苯乙烯(St)、甲基丙烯酸缩水甘油酯(GMA)和二乙烯基苯(DVB),通过种子乳液聚合,制备了不同磁含量的核壳结构的磁性复合微球.分别用X-射线衍射(XRD)、高倍透射电镜(HR-TEM)、热重分析(TGA)、振动样品磁力计(VSM)等手段对磁性微球的性能进行了表征.实验结果表明,Fe3O4/P(MMA/DVB)微球的磁含量为84 wt%;通过改变加入壳层单体的量,核壳复合微球的磁含量可控在20 wt%~76 wt%之间.该微球具有超顺磁性,相应的饱和磁化强度为12~50Am2/kg. 相似文献
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A series of crosslinked microgels with quaternary ammonium ions on the surface was prepared by quaternization with N,N-dimethylbenzylamine in the presence of microgel particles prepared by emulsion copolymerization of styrene (St), chloromethylstyrene (CMS) and divinylbenzene (DVB). Microgels with diameters in the range of 15–100 nm were successfully dispersed in organic solvents such as 2-methoxyethanol and 2-ethoxyethanol without an emulsifier. A photosensitive layer was formed by coating a photosensitive solution on a grained aluminum plate. The solution was comprised of the microgels, the multifunctional monomer and standard ultraviolet (UV) photoinitiators, such as 2,4-diethyl thioxanthone (DETX)/ethyl p-di-ethylaminobenzoate (EPA). This gave a heterogeneous photosensitive layer which produced good polymer patterns after exposure to UV light followed by development in tap water. A typical polymer layer, consisting of the microgels (poly(styrene-co-N,N-dimethylbenzylvinyl-benzylammonium chloride-co-divinylbenzene)), DETX/EPA, and the multifunctional acrylate monomers, exhibited photosensitivity of 0.06 mJ/cm2 for UV light. This sensitivity is much higher than the homogeneous photopolymerization system with an analogous composition. 相似文献
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Jianzhong Du Yongming Chen 《Journal of polymer science. Part A, Polymer chemistry》2004,42(9):2263-2271
Poly(ethylene oxide) (PEO) star polymer with a microgel core was prepared by atom transfer radical poylmerization (ATRP) of divinyl benzene (DVB) with mono‐2‐bromoisobutyryl PEO ester as a macroinitiator. Several factors, such as the feed ratio of DVB to the initiator, type of catalysts, and purity of DVB, play important roles during star formation. The crosslinked poly(divinyl benzene) (PDVB) core was further obtained by the hydrolysis of PEO star to remove PEO arms. Size exclusion chromatography (SEC) traces revealed the bare core has a broad molecular weight distribution. PEO–polystyrene (PS) heteroarm star polymer was synthesized through grafting PS from the core of PEO star by another ATRP of styrene (St) because of the presence of initiating groups in the core inherited from PEO star. Characterizations by SEC, 1H NMR, and DSC revealed the successful preparation of the target star copolymers. Scanning electron microscopy images suggested that PEO–PS heteroarm star can form spherical micelles in water/tetrahydrofuran mixture solvents, which further demonstrated the amphiphilic nature of the star polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2263–2271, 2004 相似文献
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Fluorescence properties of a series of styrene/p-divinylbenzene (St/p-DVB) copolymer beads were investigated by steady-state fluorescence spectra.In addition to the fluorescence of the phenyl ring excimer,a new emission band at ca 395nm appears when p-DVB content in feed is higher than 13%(wt). The intensity of this new emission was found to change with p-DVB content and to decrease with swollen beads. The origin of this new emission is considered to be a multi-ring excimer formation. 相似文献
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合成一种新型开-关(ON-OFF)型汞离子荧光传感分子triquinolin-8-yl benzene-1,3,5-tri-carboxylate(TQBTC)。 采用FT-IR、元素分析、1H NMR测试技术对其结构进行了表征。 在对其荧光性质的研究中发现,TQBTC的乙腈-水溶液在253.0 nm波长辐射激发下于616.0 nm处发射强荧光,且对汞离子络合有较好的选择性。 TQBTC与Hg(Ⅱ)可形成1∶3型络合物,同时使荧光线性猝灭,TQBTC可作为Hg(Ⅱ)的荧光传感分子。 建立了一种测定Hg(Ⅱ)的灵敏分析方法。 Hg(Ⅱ)浓度在0~30 μmol/L的范围内与TQBTC的荧光猝灭呈线性关系,方法检出限为0.838 μmol/L。 方法应用于实际样品中Hg(Ⅱ)的检测,获得满意结果。 相似文献
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Zheng-You Ding Shenmin Ma Dennis Kriz J. J. Aklonis R. Salovey 《Journal of Polymer Science.Polymer Physics》1992,30(11):1189-1194
Monodisperse sized crosslinked polystyrene (PS) beads prepared by reaction of styrene (S) and divinylbenzene (DVB), in batch emulsion copolymerization in the absence of emulsifiers, are not uniformly crosslinked, because DVB is more reactive than S. For copolymerization of 1 to 10 mol % DVB and S, within each crosslinked PS microbead, the crosslink density varies by a factor exceeding two and decreases with increased conversion. A semicontinuous copolymerization, involving incremental additions of DVB, produces uniformly crosslinked PS beads. For both copolymerization techniques, Tg correlates well with crosslink density and PS beads are spherical and monodisperse in size. © 1992 John Wiley & Sons, Inc. 相似文献
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Azido chelating fiber: synthesis,characterization and adsorption performances towards Hg2+ and Pb2+ from water 下载免费PDF全文
Herein, we report the synthesis and adsorption property of a novel chelating fiber containing azido group. Firstly, the brominated fiber (PP‐St‐DVB‐Br) was obtained via the reaction of polypropylene‐(g)‐styrene‐divinylbenzene fiber (PP‐St‐DVB) with bromine in CH2Cl2 solution. Then, azido chelating fiber (PP‐St‐DVB‐N3) was prepared by azidation of PP‐St‐DVB‐Br fiber. Its structure and properties were characterized by Fourier transform infrared, elemental analysis, thermogravimetric analysis, and chemical titration, respectively. The micromophology and functional group distribution in fibrous matrix were investigated by scanning electron microscopy‐energy dispersive spectroscopy. The results show that the chelating fiber has high functional group contents (2.11 mmol/g for PP‐St‐DVB‐N3) and uniform distribution. Different from granulate chelating resin, the novel fibrous adsorbent possesses excellent adsorption ability for Hg(II) and Pb(II) ions (408.9 mg/g for Hg2+ and 334.4 mg/g for Pb2+), and the adsorption capacity of the fiber has no loss until five cycles. The novel absorbent material shows the potential application prospect in the treatment of heavy metal wastewater. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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The emission spectra of quinidine and quinidine sulfate doped in sol‐gels (tetraethoxysiliane system) have been measured during the sol‐gel transformation. Shifts in the emission spectra from 370 nm to 435 nm were observed in both molecules as the system changed from sol stage to dried glass over a period of two weeks. These shifts are attributed to the conformational changes of the doped molecules. In addition, the process of the signal changes was observed by an emerging new band at ?435 nm with a concomitant decline of the original band at 370 nm during the sol‐gel transformation. These results indicate that the conformational changes induced by the sol‐gel transformation are accomplished in one step instead of several intermediate states. 相似文献