Monolithic polymeric sorbents for high-performance chromatography of synthetic polymers

A number of macroporous monolithic materials based on copolymers of butyl methacrylate or lauryl methacrylate with ethylene glycol dimethacrylate is obtained via thermal free-radical polymerization. The effect of polymerization conditions on pore parameters of the synthesized sorbents is studied. Polymer stationary phases obtained for the efficient analysis of synthetic polymers are tested for the separation of a multicomponent mixture containing polystyrene samples of various molecular masses.     

Macroporous polystyrene-supported quaternary ammonium salt catalysts for the addition of carbon dioxide to glycidyl methacrylate

In the present study, the synthesis of (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate (DOMA) from carbon dioxide and glycidyl methacrylate (GMA) was investigated in a semi-batch reactor using macroporous polystyrene beads containing pendant quaternary ammonium salt catalysts. The catalysts were prepared by partial copolymerization of styrene (ST) and divinylbenzene (DVB) with isooctyl alcohol, and then by copolymerization with vinylbenzyl chloride (VBC). Quaternization of the pendant chloromethyl groups was carried out by using trialkylamines. The catalytic activity of the macroporous polymer was influenced by VBC and isooctyl alcohol concentration, and by the structure of trialkylamine. A kinetic study was also carried out to better understand the reaction steps. This revised version was published online in June 2006 with corrections to the Cover Date.     

Macroporous ZrO2 ceramics prepared from colloidally stable nanoparticles building blocks and organic templates

ZrO2 macroporous materials with well-ordered structures were prepared using nano-ZrO2 particles as the building materials and polystyrene spheres as the organic templates. A well-dispersed nano-ZrO2 suspension with a narrow particle size distribution was prepared by deagglomeration of as-received nano-ZrO2 powders via ultrasonication, and then centrifugation was performed to remove agglomerated bigger particles. Negatively charged polystyrene spheres were uniformly coated with positively charged nano-ZrO2 particles by means of electrostatic attraction at pH 4. Green samples were prepared by slip casting from colloidally stable suspension of nano-ZrO2 coated polystyrene spheres. ZrO2 macroporous materials with well-ordered microstructure derived from the nano-ZrO2 coated polystyrene spheres.     

Three-dimensionally ordered macroporous cross-linked polystyrene incorporating functional group via hydrophilic spacer arm

<正>A versatile and effective method for incorporating functional groups on the pore wall of three-dimensionally ordered macroporous cross-linked polystyrene(3DOM CLPS) by hydrophilic spacer arm has been investigated.The 3DOM CLPS with pore size 865 nm was prepared by sacrifice template method.The hydrophilic spacer arm(polyethylene glycol,molecular weight is 600) was grafted to the 3DOM CLPS via nucleophilic substitution reaction.The other side of active hydroxyl can be further converted into a lot of other functional groups.In this report,the chelating ligand 2-mercaptobenzothiazole(MBZ) group was introduced on the end of the PGE chain to evidence the versatile functionalization approach.The functionalized ordered macroporous materials were characterized by FT-IR,element analyzer,SEM.The results reveal that the pores were successfully bonded with 2-mercaptobenzothiazole groups via hydrophilic spacer arms and the original morphology of ordered macroporous materials were remained after functionalization.The MBZ group density is 0.052 mmol/m~2.The functionalized 3DOM CLPS are expected to application as heavy metal ions adsorbent.     

Immobilization of anionic iron(III) porphyrins into ordered macroporous layered double hydroxides and investigation of catalytic activity in oxidation reactions

The first generation anionic iron(III) porphyrin [Fe(TSPP)] and the second generation anionic complexes [Fe(TDFSPP)], [Fe(TCFSPP)], and [Fe(TDCSPP)] were immobilized into three-dimensionally macroporous layered double hydroxide (3DM-LDH), using the direct reconstruction of 3DM-LDH from macroporous mixed oxides MOX or the anionic exchange on DDS intercalated 3DM-LDH. The macroporous layered double hydroxides were obtained at the surface of nanometric polystyrene spheres, which were synthesized by an inverse opal method. Polystyrene was removed after calcination in oxidizing atmosphere, nanostructured mixed oxides (3DM-MOX) were obtained, which after reconstruction give origin to macroporous layered double hydroxide (3DM-LDH). Following metalloporphyrin immobilization, the resulting materials were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), UV–vis (glycerin mull) spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FTIR), and electron paramagnetic resonance (EPR). Results revealed that the complexes are either immobilized at the surface of the macroporous layered double hydroxide or intercalated between the layers, displacing some dodecylsufate anions. The obtained materials were investigated as catalysts for oxidation reactions, to find out whether they function as cytochrome P-450 models.     

Separation of linear and star-shaped polystyrenes by phase distribution chromatography

The phase distribution chromatographic technique was optimized and applied for the separation of linear and star-shaped polystyrene (PS). For this purpose non-crosslinked, ultra high molecular weight PS coated on different supporting materials was used. The stability of the coating under chromatographic conditions was tested by thermo gravimetric analysis and microscopic techniques. The modification of different column packing materials was tested. Separation according to branching was indicated for different molecular weights of linear and star-shaped PS. The resolution of the separation was improved by changing the density of the stationary phase and the temperature. The separation results were supported by cloud point measurements and the determination of the critical conditions for linear and star-polymers at the same molecular weight.     

三维有序大孔复合材料AgZnO-TiO2的制备及微波辅助光催化性能

采用聚苯乙烯(PS)微球作为模板剂,经溶胶-凝胶及煅烧后处理等方法制备了三维有序大孔复合材料Ag/ZnO-TiO2. 通过傅里叶-红外光谱(FT-IR)、X 射线衍射(XRD)、X 射线光电子能谱(XPS) 、N2吸附-脱附测定和扫描电子显微镜配合X 射线能量色谱仪(SEM-EDS)等测试手段对其组成、结构及形貌等进行了表征. 结果显示,经PS微球处理后的Ag/ZnO-TiO2具有锐钛矿晶型结构,其Ag以单质形式存在. 该复合材料的孔结构排列整齐有序,孔壁为介孔结构,粒子堆积致密,平均孔直径约150 nm,属于三维有序大孔材料(3DOM). 在微波辅助光催化降解甲基橙等染料的实验研究中,该复合材料表现出较好的光催化性能,其活性明显高于P25等单体以及二元体系ZnO-TiO2     

三维有序大孔杂化SiO2的制备、表征及应用

将有机-无机杂化功能材料与有序大孔材料独特的有序开孔结构相结合,在制备的三维有序大孔二氧化硅(3DOM Si O2)孔壁上可控接枝带有功能基团的聚合物链段,制备3DOM杂化材料。采用表面引发原子转移自由基(SI-ATRP)接枝技术在3DOM Si O2孔壁上可控接枝聚甲基丙烯酸缩水甘油酯(PGMA)链段,讨论了接枝条件对接枝量及接枝链段分子量的影响,并利用FTIR、SEM、TGA、GPC等对接枝过程进行了表征。PGMA接枝链段上环氧基团可进一步与亲核试剂(二乙醇胺,浓硫酸和二乙烯三胺)发生开环反应,得到一系列带有不同官能团的具有较高接枝密度的功能杂化多孔材料,同时,利用该种材料对水中的水杨酸进行了吸附实验,吸附结果表明经二乙烯三胺开环后得到的功能化多孔材料对水杨酸具有很高的吸附量。     

三维有序大孔杂化SiO2的制备、表征及应用

本研究将有机-无机杂化功能材料与有序大孔材料独特的有序开孔结构相结合,在制备的三维有序大孔二氧化硅（3DOM SiO₂）孔壁上可控接枝带有功能基团的聚合物链段,制备3DOM杂化材料。采用表面引发原子转移自由基（SI-ATRP）接枝技术在3DOM SiO₂孔壁上可控接枝聚甲基丙烯酸缩水甘油酯（PGMA）链段,讨论了接枝条件对接枝量及接枝链段分子量的影响,并利用FT-IR、SEM、TGA、GPC等对接枝过程进行了表征。PGMA接枝链段上环氧基团可进一步与亲核试剂（二乙醇胺,浓硫酸和二乙烯三胺）发生开环反应,得到一系列带有不同官能团的具有较高接枝密度的功能杂化多孔材料,同时,利用该种材料对水中的水杨酸进行了吸附实验,吸附结果表明经二乙烯三胺开环后得到的功能化多孔材料对水杨酸具有很高的吸附量。本研究对于发展新型杂化多孔材料提供了新的方法。     

N‐Bromosuccinimide as a thermal iniferter for radical polymerization

N‐Bromosuccinimide (NBS) was used as a thermal iniferter for the initiation of the bulk polymerizations of methyl methacrylate, methyl acrylate, and styrene. The polymerizations showed the characteristics of a living polymerization: both the yields and the molecular weights of the resultant polymers increased linearly as the reaction time increased. The molecular weight distributions of the polymers were 1.42–1.95 under the studied conditions. The resultant polymers could be used as macroiniferters to reinitiate the polymerization of the second monomer. The copolymers poly(methyl methacrylate)‐b‐polystyrene and polystyrene‐b‐poly(methyl methacrylate) were obtained and characterized. End‐group analysis of the resultant poly(methyl methacrylate), poly(methyl acrylate), and polystyrene confirmed that NBS behaved as a thermal iniferter. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2567–2573, 2005     

Preparation and characterization of macroporous polystyrene resins containing ethynyl groups and transition metal acetylide complexes

Ethynylated polystyrene resins were prepared as functionalized polymer supports by the iodination reaction of macroporous polystyrene resins and reacted with transition metal diethynyl complex (Mt = Ni) and metal halides (Mt = Rh, Pd, and Pt) in a basic solvent using cuprous iodide as a catalyst to obtain macroporous polystyrene resins containing organotransition metals. The distribution of the metal acetylide complexes in the modified macroporous resins was determined by an electron probe microanalyzer. A gradient in the transition metal distribution was observed in any case of the modified resins. The stability of the organotransition metal complexes in the polymer matrix could be compared with a low molecular weight analogous complex quantitatively.     

Organic polymer monoliths as stationary phases for capillary HPLC

Modern rigid porous polymer monoliths were conceived as a new class of stationary phases in classical columns in the early 1990s and later extended to the capillary format. These monolithic materials are typically prepared using a simple molding process carried out within the confines of the capillary. Polymerization of a mixture comprising monomers, initiator, and porogenic solvent affords macroporous materials with large through-pores that enable applications in a rapid flow-through mode. Since all the mobile phase must flow through the monolith, convection considerably accelerates mass transport within the monolithic separation medium and improves the separations. As a result, monolithic columns perform well even at very high flow rates. Various mechanisms including thermally and UV initiated free radical polymerization as well as ring opening metathesis copolymerizations were demonstrated for the preparation of monolithic capillary columns. The versatility of these preparation techniques was demonstrated by their use with hydrophobic (styrene, divinylbenzene, butyl methacrylate, ethylene dimethacrylate), hydrophilic (2-hydroxyethyl methacrylate, methacrylamide, methylenebisacrylamide), ionizable (vinylsulfonic acid, 2-acrylamido-2-methyl-propanesulfonic acid), and tailor-made (norborn-2-ene, 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene) monomers. Variation of polymerization conditions enables control of the porous properties of the monolith over a broad range and mediates the hydrodynamic properties of the monolithic columns. The applications of polymer-based monolithic capillary columns are demonstrated for numerous separations in the microHPLC mode.     

Liquid chromatography of polymer mixtures applying a combination of exclusion and full adsorption mechanisms. 5. Six-component blends of chemically similar polymers

The separation of six-component blends of chemically similar homopolymers utilising the full adsorption-desorption (FAD) process is presented. The main advantage of the FAD approach over other methods represents the successive and independent size- exclusion chromatography (SEC) characterisation of all blend components. The method is based on the full adsorption and retention of all n or n−1 components of the polymer blend from an adsorption promoting liquid (ADSORLI) in a small FAD column. Nonadsorbed macromolecules are forwarded directly into SEC for molecular characterisation. Next, appropriate displacers are successively applied to the FAD column to selectively release preadsorbed blend constituents into the on-line SEC column. Dynamic integral desorption isotherms for single constituents, as well as for polymer blends to be analysed, allow identification of optimal displacer compositions to release just one kind of macromolecule. Model polymer blends containing polystyrene (PS), poly(lauryl methacrylate), poly(butyl methacrylate), poly(ethyl methacrylate), poly(methyl methacrylate) and poly(ethylene oxide) (PEO) or, alternatively, PS, poly(2-ethylhexyl acrylate), poly(butyl acrylate), poly(ethyl acrylate), poly(methyl acrylate) and PEO of similar molar masses can be separated and characterised in one multistep run using nonporous silica FAD packing, toluene as an ADSORLI and its mixtures with a desorption promoting liquid such as ethyl acetate, tetrahydrofuran or dimetylformamide to form displacers with appropriate desorption strength. Received: 9 September 1998 Accepted in revised form: 16 November 1998     

Fabrication of Porous Titania Particles from Water-in-Oil Emulsions for the Applications of Photocatalyst

In this study, polystyrene nanospheres were synthesized by dispersion polymerization using batch-type reactor for the self-organization with precursor materials inside emulsion droplets. Mechanical homogenization was applied for the emulsification of the polymeric nanospheres and titanium diisopropoxide bis (acetylacetonate) to produce the macroporous titania particles by evaporation-driven self-assembly. Similarly, spherical titania crystallites could be synthesized via self-organization using triblock copolymer instead of polymeric latex beads after successive calcination. The morphologies of the porous particles were observed using electron microscope, and the crystallinity of the porous titania particles was analyzed by powder x-ray diffraction. As a demonstrative application, the macroporous titania microparticles with anatase phase were adopted as photocatalyst for the decomposition of Rhodamine B, and excellent catalytic performance was observed with higher rate constant compared to the result from commercial titania nanocolloid. Collectively, our macroporous titania microparticles were found to be safe catalytic materials for human body minimizing the skin toxicity since the size of the catalysts is in the micron-range.     

Poly(alkyl methacrylate) monolithic columns for HPLC

Several monolithic macroporous polymer sorbents (pore size 1–2 µm) based on alkyl methacrylates and ethylene glycol dimethacrylate as a cross-linking agent were prepared by free radical copolymerization in columns 3×150 mm. The influence of compositions of the reaction mixture and porogens and the nature of the alkyl radical in a mixture of monomers on the hydrodynamic and chromatographic characteristics of the monoliths was studied. The monoliths based on n-butyl methacrylate have rigid macroporous morphology and excellent hydrodynamic characteristics (flow rate up to 5 mL min^?1). The efficiency of separation of a mixture of benzene and its derivatives in the version of reversed-phase HPLC was shown to increase with an increase in the fraction of a lauryl methacrylate additive (LMA) in the reaction mixture. The maximum separation efficiency (number of theoretical plates (tp)) was 35 000 tp m^?1 for the monolith based on n-butyl methacrylate with 7% LMA in the reaction mixture.     

作为锂离子电池负极材料的三维有序大孔SnO2的 制备及表征

通过聚苯乙烯(PS)胶晶模板法合成了三维有序大孔(3DOM) SnO2. 运用扫描电镜、热重分析、X射线衍射、电化学充放电等多种方法对其结构和性能进行了表征和研究. SEM图表明PS胶晶模板微球排列规整, 大小均匀(直径275±10 nm), 形成多层六方紧密堆积排列; 煅烧除去模板后的3DOM SnO2呈三维多孔网络结构, 具有圆型和六边形的孔隙形貌, 其孔径大小为(215±10) nm; 孔壁由SnO2纳米晶粒组成, 壁厚为20～30 nm. XRD图谱表明经过煅烧除去模板后, 形成了纯SnO2相. 当作为锂离子电池负极材料时, 3DOM SnO2表现出较好的充放电容量和库仑效率. 此外, 这种合成方法简单、经济, 可进一步应用于其它锂离子电池材料的合成.     

漂浮法制备SiO2有序大孔材料

用漂浮组装方法以亚微米尺度单分散的聚苯乙烯(PS)微球作为模板, 在悬浮液气-液界面处组装PS模板微球与纳米级胶体颗粒, 形成二元胶体颗粒共混物, 再去除模板得到有序大孔材料.     

单体对聚乙烯醇乳化行为的影响及大孔材料的制备

以聚乙烯醇-1788(PVA-1788)为表面活性剂,研究了3种甲基丙烯酸酯系列水溶性单体对水包二氧化碳(C/W)型高内相乳液(HIPE)的形成及稳定性的影响,然后采用HIPE模板法制备了两种大孔材料.结果表明,甲基丙烯酰氧乙基三甲基氯化铵的存在对C/W型HIPE的形成及稳定影响较小,所得乳液最高能稳定48 h;而甲基...     

Synthesis of polar block grafted syndiotactic polystyrenes via a combination of iridium‐catalyzed activation of aromatic C?H bonds and atom transfer radical polymerization

A combination of iridium‐catalyzed C H activation/borylation and atom transfer radical polymerization (ATRP) was used to generate polar graft copolymers of syndiotactic polystyrene (sPS). The borylation at aromatic C H bonds of sPS and subsequent oxidation of boronate ester proceeded without negatively affecting the molecular weight properties and the tacticity of sPS. A macroinitiator suitable for ATRP could be synthesized by the esterification of 2‐bromo‐2‐methylpropionyl bromide and hydroxy‐functionalized sPS. The graft polymerizations of methyl methacrylate and tert‐butyl acrylate from the macroinitiator using ATRP afforded polar block grafted sPS materials, syndiotactic polystyrene‐graft‐poly(methyl methacrylate) (sPS‐g‐PMMA) and syndiotactic polystyrene‐graft‐poly(tert‐butyl acrylate) (sPS‐g‐PtBA). The latter was hydrolyzed to yield an amphiphilic graft copolymer, syndiotactic polystyrene‐graft‐poly(acrylic acid) (sPS‐g‐PAA). The structures of the copolymers were characterized by NMR and FTIR spectroscopies. Size exclusion chromatography and ¹H NMR spectroscopy were used to study any changes in the molecular weight properties from the parent polymer. A decrease in the hydrophobicity of the graft copolymers was confirmed by water contact angle measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6655–6667, 2009     

Controlled Anionic Synthesis of Poly[2‐(3‐nitrocarbazolyl)ethyl methacrylate]

Poly[2‐(3‐nitrocarbazolyl)ethyl methacrylate] (poly(NCzMA)) with controlled molecular weight and narrow molecular weight distribution was successfully synthesized using (methyl methacryloyl)potassium (MMA) as a weak initiator in the presence of diethylzinc (Et₂Zn) in THF at –78°C. Et₂Zn acted both as an additive for the coordination with enolate anion and nitro group and as a scavenger to remove impurities. Block copolymers PMMA‐block‐poly(NCzMA)‐block‐PMMA and poly(NCzMA)‐block‐PS‐block‐poly(NCz‐MA), were also synthesized quantitatively (PMMA: poly(methyl methacrylate), PS: polystyrene). The results indicate that Et₂Zn can be used to synthesize the polymers of solid, nitro group‐containing methacrylate monomers by anionic polymerization in THF.