超亲水聚偏氟乙烯中空纤维膜的制备及性能

采用超声辅助接枝聚合技术, 将甲基丙烯酸缩水甘油酯(GMA)接枝到聚偏氟乙烯(PVDF)膜表面, 制备PVDF-g-GMA膜; 再利用氨基诱导环氧基团发生开环反应, 将苏氨酸(Thr)接枝到PVDF-g-GMA膜表面, 制备了具有两性离子结构表面的PVDF-g-GMA-Thr膜. 通过衰减全反射傅里叶变换红外光谱(ATR-FTIR)、 X射线光电子能谱(XPS)、 接触角测试仪、 场发射扫描电子显微镜(FESEM)和牛血清白蛋白(BSA)过滤实验等系统研究了改性前后PVDF膜表面的化学组成、 润湿性能、 表面形貌和抗污染性能. 研究结果表明, 随着PVDF-g-GMA接枝Thr反应时间的增加, PVDF-g-GMA-Thr膜的亲水性能明显提高, 接触角从90°降为0°, 呈现出超亲水性能. 同时PVDF-g-GMA-Thr膜的水通量明显提高, 当Thr诱导开环反应时间为12 h时, PVDF-g-GMA-Thr膜的水通量高达686 L/(m ²·h), 与PVDF原膜相比, 水通量提高了204.5%. 在BSA的过滤测试中, 与PVDF膜相比, PVDF-g-GMA-Thr膜呈现出良好的截留性能和抗污染性能, BSA截留率从42%提高到84%,水通量恢复率从53%提高到87%, 不可逆污染率从47%降到12%, 表明通过接枝Thr构筑两性离子结构表面可以有效减小膜污染.     

Modification of polyethylene films by radiation grafting of glycidyl methacrylate and immobilization of β-cyclodextrin

Glycidyl methacrylate was grafted onto polyethylene films using a preirradiation method with γ rays. The effect of absorbed dose, monomer concentration, and reaction time on the degree of grafting was determined. The grafted samples were verified by FTIR-ATR spectroscopy. β-Cyclodextrin was immobilized onto polypropylene modified with glycidyl methacrylate, and the ability of the cavities of β-cyclodextrin to form inclusion complexes was demonstrated using the typically organic compound approach with m-toluic acid (3-MBA) as a probe.     

聚乙烯表面接枝聚合改性及抗凝血性的研究

聚乙烯(PE)膜经Ar等离子体预处理,无光引发剂紫外光照接枝甲基丙烯酸缩水甘油酯(GMA),然后进行肝素化处理,以改善PE的抗凝血性能。用正交实验确定接枝反应的最优条件。通过X-射线光电子能谱(XPS)、衰减全反射红外光谱(ATR-FTIR)、扫描电子显微镜(SEM)和接触角测定PE膜接枝GMA前后表面性能和表面形貌。用复钙时间、凝血酶原时间、部分凝血活酶时间、凝血酶时间和血小板粘附实验对其抗凝血性能进行评价,结果表明,被修饰PE膜的抗凝血性能显著提高。     

聚甲基丙烯酸酯改性聚氨酯光固化水性体系研究

水性涂料;聚甲基丙烯酸酯改性聚氨酯光固化水性体系研究;接枝共聚物;聚氨酯丙烯酸酯;丙烯酸酯共聚物     

基于原子转移自由基聚合制备新型螯合树脂及其吸附性能

以氯甲基化聚苯乙烯树脂(CMPS)为基质, 通过表面引发原子转移自由基聚合(SI-ATRP)反应将聚甲基丙烯酸缩水甘油酯(PGMA)接枝到树脂表面, 再与亚氨基二乙酸(IDA)反应, 制备了一种新型螯合树脂. 采用红外光谱、 元素分析及比表面积与微孔分析仪对其结构进行表征. 树脂表面甲基丙烯酸缩水甘油酯(GMA)接枝量和IDA含量及对Ni(Ⅱ), Cu(Ⅱ)和Pb(Ⅱ)的吸附容量均随聚合时间的延长而增大, 聚合时间为18 h时, 最大吸附容量分别为1.29, 1.19和0.83 mmol/g. 结果表明, SI-ATRP是制备高吸附容量及吸附容量可控的螯合树脂的可行方法.     

Radical Graft Polymerization of Vinyl Monomers Initiated by A20 Groups Introduced Onto a Carbon Black Surface: Effect of azo Groups on Graft Polymerization

The radical graft polymerization of vinyl monomers from carbon black initiated by azo groups introduced onto the surface was investigated. The introduction of azo groups onto carbon black surface was achieved by three methods: the reaction of 2,2′-azobis[2-(2-imidazolin-2-yl)propane] (AIP) with (1) epoxide groups, which were introduced by the reaction of carbon black with chlorometh-yloxirane; (2) acyl chloride groups, which were introduced by the reaction of carboxyl groups on the surface with thionyl chloride; and (3) 3-chloroformyl-1-cyano-1-methylpropyl groups, which were introduced by the reaction of carbon black with 4,4′-azobis(4-cyanovaleric acid) and then thionyl chloride. The amount of azo groups introduced onto the surface by the above methods was determined to be 0.07-0.19 mmol/g. The graft polymerization of methyl methacrylate was found to be initiated by azo groups introduced onto the carbon black surface. During the polymerization, poly(methyl methacrylate) was effectively grafted onto carbon black through propagation of the polymer from the radical produced on the surface by the decomposition of the azo groups. The percentage of grafting using carbon black having azo groups introduced by method 1 increased to 40%. It was also found that the graft polymerization of several vinyl monomers such as styrene, acrylonitrile, and acrylic acid was initiated by the azo groups introduced onto the surface and the corresponding polymer was effectively grafted onto the surface. Furthermore, the effect of the amount of carbon black having azo groups on the graft polymerization was investigated.     

Grafting of glycidyl methacrylate onto polypropylene using supercritical carbon dioxide

Free-radical grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) films has been studied using supercritical carbon dioxide (SC-CO₂) as a solvent and a swelling agent. As the reaction temperature was below the melting point, PP was modified in the solid phase. The PP film was first soaked with the monomer GMA and benzoyl peroxide (BPO) as an initiator using SC-CO₂ at different experimental conditions of pressure, temperature, and thermal treatment time. After releasing CO₂, film GMA molecules were grafted onto PP in different times. Using this method, the degree of grafting and the morphology could be controlled through the combination of pressure, temperature, and soaking time. FTIR spectra confirmed that GMA had been grafted onto PP and that polypropylene-graft-glycidyl methacrylate (PP-g-GMA) presented a high surface reactivity for conductive polyaniline anchoring. DSC measurements and TG analyses showed that the thermal profiles of the graft copolymer and virgin PP are quite similar and that the graft PP does not exhibit changes in terms of thermal degradation profile and melting temperature, respectively. X-ray data showed that a high degree of grafting leads to a lower degree of crystallinity of polypropylene.     

Surface modification of polymers. II. Grafting with glycidyl acrylates and the reactions of the grafted surfaces with amines

The surface of low density polyethylene has been grafted with glycidyl acrylate and glycidyl methacrylate by photoinitiation. ESCA measurements on the grafted surface showed a 72% coverage for glycidyl acrylate and 52% for glycidyl methacrylate after 10 min of grafting with UV irradiation. ATR–IR showed a 10 times more extensive grafting for glycidyl acrylate than for glycidyl methacrylate after 10 min of grafting, indicating reaction to deeper layers. Acetone and ethanol were used as solvents: acetone yielded slightly more grafting at the surface. The grafted surfaces were reacted with 2M solutions of aniline and propylamine in ethanol. After 4 h reaction at 60°C, with aniline 52% of the epoxy groups while for propylamine 96% of the groups were consumed, as measured with ATR–IR.     

GMA熔融接枝EPDM的研究

以甲基丙烯酸缩水甘油酯（ＧＭＡ）为接枝单体，过氧化二异丙苯（ＤＣＰ）为引发剂，对三元乙丙胶（ＥＰＤＭ）进行了熔融接枝，在烃链上引入极性基团，以改善ＥＰＤＭ与极性聚合物的相容性。用差示扫描量热计（ＤＳＣ）研究了ＧＭＡ的聚合温度，用富里叶红外（ＦＴ－ＩＲ）、凝胶渗透色谱（ＧＰＣ）对接枝产物进行了表征。实验结果表明，产物的接枝率和凝胶量可以通过反应条件（温度、时间、反应物组成及加料方式）来控制。     

Topochemistry of cellulose nanofibers resulting from molecular and polymer grafting

The aim of this study was to synthesize hydrophobic cellulose nanofibers (CNFs) using different chemical treatments including polymer and molecular grafting. For polymer grafting, immobilizing poly (butyl acrylate) (PBA) and poly (methyl methacrylate) (PMMA) on CNFs were implemented by the free radical method. Also, acetyl groups were introduced directly onto the CNFs surface by acetic anhydride for molecular grafting. The gravimetric and X-ray photoelectron spectroscopy analysis showed the high grafting density of PMMA on the surface of CNFs. AFM results revealed that molecular grafting created non-uniformity on the CNFs surface, as compared to polymer brushes. In addition, thermodynamic work of adhesion and work of cohesion for the modified CNFs were reduced in water and diiodomethane solvents. Dispersion factor was studied to indicate the dispersibility of CNFs in polar and non-polar media. Dispersion energy was reduced after modification as a result of decreasing interfacial tension and the dispersibility of modified CNFs was improved in diiodomethane.     

Surface grafting onto SiC nanoparticles with glycidyl methacrylate in emulsion

To improve the tribological performance of nano‐SiC particles filled epoxy composites, surface modification of the fillers is necessary. By means of soapless emulsion polymerization method, graft polymerization of glycidyl methacrylate (GMA) onto the surface of alkyl nano‐SiC was carried out, resulting in composite particles with SiC core and polymeric shell in which polyglycidyl methacrylate (PGMA) is chemically attached to the nanoparticles by the double bonds introduced during the pretreatment with a coupling agent. By analyzing the reaction mechanism, the emulsion polymerization loci were found to be situated at the SiC surface. Also, the factors affecting the grafting yielding of PGMA on the particles were investigated, including monomer concentration, initiator consumption, reaction temperature, reaction time, etc. Accordingly, an optimum grafting reaction condition was determined. It was shown that the grafted nanoparticles exhibit greatly improved dispersibility in good solvent for the grafting polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3842–3852, 2004     

Surface modification of silica nanoparticles by UV-induced graft polymerization of methyl methacrylate

In this study we modified the surface of silica nanoparticles with methyl methacrylate by UV-induced graft polymerization. It is a surface-initiated polymerization reaction induced by ultraviolet irradiation. The resulting organic-inorganic nanocomposites were near-monodisperse and fabricated without homopolymerization of the monomer. Substantial increase in mean particle size was observed by SEM image analysis after UV-induced grafting of methyl methacrylate onto pure silica particles. FT-Raman spectroscopy and X-ray photoelectron spectroscopy studies of these materials revealed the successful grafting of methyl methacrylate onto the silica surface. The formation of a covalent bond between the grafted PMMA chains and silica surface was indicated by FT-Raman spectra. Thermogravimetric analysis of the PMMA-grafted silica particles indicated the polymer contents in good agreement with SEM photographs.     

Covalent immobilization of chitosan on surfaces with anchoring layers of poly(glycidyl methacrylate) and maleic anhydride copolymers

The method for producing chitosan coatings on solid surfaces with anchoring layers of poly(glycidyl methacrylate) and maleic anhydride copolymers has been proposed. It is shown that, owing to a high reactivity of epoxy and anhydride groups, the efficiency of immobilization and the stability of the coatings are considerably higher than those prepared by the conventional method of chitosan grafting onto the surface modified by poly(acrylic acid). The properties of chitosan coatings are examined via atomic force microscopy, X-ray photoelectron spectroscopy, ellipsometry, and electrokinetic measurements. Depending on the anchoring layer used, the total thickness of the coatings is 6–16 nm with an rms roughness less than 1.2 nm, while the isoelectric points of the surfaces modified with chitosan are located in the pH range 5–6.     

Graft polymerization of methyl methacrylate from silica initiated by peroxide groups introduced onto the surface

The surface grafting onto ultrafine silica by the radical polymerization of methyl methacrylate (MMA) initiated by peroxide groups introduced onto the surface was investigated. The introduction of peroxide groups onto the silica surface was achieved by the reaction of hydrogen peroxide with chlorosilyl groups, which were introduced by the treatment of silica with thionyl chloride. The content of diisopropylbenzene peroxide and tert-butyl peroxide groups introduced onto the silica according to the above method was determined to be 0.11 and 0.08 mmol/g, respectively. It was found that the polymerization of MMA is initiated by silica having these peroxide groups. In the polymerization, polyMMA was grafted onto silica surface: the percentage of grafting reached about 70%. Therefore, it was concluded that the polymerization of MMA is initiated by surface radicals formed by the decomposition of peroxide groups on silica and polyMMA is grafted through the propagation from the surface. During the polymerization, ungrafted polyMMA was also formed because of the formation of initiator fragments by the decomposition of peroxide groups: the grafting efficiency of the graft polymerization was 30–40%. PolyMMA-grafted silica produced a stable colloidal dispersion in organic solvents for polyMMA. © 1992 John Wiley & Sons, Inc.     

三醋酸纤维素膜辐射可控接枝甲基丙烯酸缩水甘油酯及其性能

三醋酸纤维素(CTA)是一种高强度的天然高分子衍生物,对其进行表面接枝改性将扩展其在物质分离、吸附、检测等领域的广泛应用,但是化学接枝改性CTA比较困难。 本文结合辐射引发接枝和可逆加成-断裂链转移(RAFT)聚合方法,成功地在CTA膜表面可控接枝了聚甲基丙烯酸缩水甘油酯(PGMA)。 研究了吸收剂量、单体GMA质量分数和RAFT试剂含量等因素对接枝率的影响,采用傅里叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)和接触角技术手段对CTA膜接枝前后的结构、形貌和表面性质进行了表征。 实验结果表明,为了得到较高的接枝率,同时又保持较好的形貌,合适的条件为:吸收剂量为10~12 kGy,GMA质量分数为30%,RAFT试剂与GMA的物质的量比为1：400;在不同条件下得到的最高接枝率为41%,接枝聚合物相对分子质量分布最低为1.33。 此外,接枝PGMA后的CTA膜疏水性增加。 该工作提供了可控接枝CTA的简便方法,与传统辐射接枝相比,RAFT辅助辐射接枝反应更加可控,得到的PGMA接枝链更加均匀,有利于根据实际应用来控制接枝率和进行后续的功能修饰。     

Preparation and properties of some water-soluble,comb-shaped,amphiphilic polymers

Water-soluble comb-shaped polymers were prepared through grafting of poly(ethylene glycol) monomethyl ethers (MPEG) onto acrylic and methacrylic ester copolymers by transesterification reactions. The grafting was alkali-catalyzed, and performed in refluxing toluene solution or in melt at 155°C. The grafting efficiency was found to be on the order of 1 graft/10 monomer units. Epoxy groups in glycidyl methacrylate copolymers were also utilized for grafting. The crude graft copolymers were purified through chromatography and characterized by NMR and IR spectroscopy. Polymers prepared from MPEG 2000 were crystalline with melting points 10–15°C lower than the MPEG used. All polymers were shown to be surface active with CMC on the order of 1.5 g/L, and surface tensions of 38–45 dyn/cm. When used as emulsifiers the graft copolymers containing bulky lipophilic ester groups (2-ethylhexyl t-butyl) gave oil-in-water (o/w) and water-in-oil (w/o) emulsions from xylene/water with higher stability than those containing straight chain ester groups (methyl nbutyl n-docecyl). The most stable emulsions were obtained by dissolving the polymers in the organic phase.     

A cation-exchange material for protein separations based on grafting of thiol-terminated sulfopropyl methacrylate telomers onto hydrophilized monodisperse divinylbenzene particles

A strong cation-exchange separation material has been prepared from monodisperse divinylbenzene particles modified by a "grafting to" approach, utilizing as anchoring points epoxy groups introduced onto the surface of the particles via oxidation of residual vinyl groups. The grafted chains consisted of thiol-terminated telomers of sulfopropyl methacrylate prepared by iniferter mediated polymerization, and grafting was performed by reaction of the corresponding thiolate anion with the surface epoxy groups. Attachment through epoxy moieties that were subsequently converted into 2,3-propanediol groups increased the hydrophilicity of the polymeric particles and incubation experiments showed no signs of the proteins denaturing on the column during an extended contact time of 1 h at room temperature. The performance of the grafted material was demonstrated by the chromatographic separation of cytochrome C, lysozyme, myoglobin, and ribonuclease A, in a cation-exchange mode.     

Photografting of vinyl polymers onto ultrafine inorganic particles: Photopolymerization of vinyl monomers initiated by AZO groups introduced onto these surfaces

The photografting of polymers onto ultrafine inorganic particles, such as silica and titanium oxide, initiated by azo groups introduced onto these surfaces was investigated. The introduction of azo groups onto the particles was achieved by the reaction of 4,4′-azobis(4-cyanopentanoic acid) with surface isocyanate groups, which were introduced by the treatment with tolylene 2,4-diisocyanate. It was found that the photopolymerization of vinyl monomers, such as methyl methacrylate (MMA), styrene, and N-vinylcarbazole, is initiated by ultrafine particles having azo groups. The corresponding polymers were effectively grafted onto these surfaces through the propagation of the polymer from the surface radicals formed by the photodecomposition of the azo groups: e.g., the percentage of grafting of PMMA and polystyrene onto silica was reached to 112 and 176%, respectively. The percentage of grafting onto silica in the graft polymerization initiated by photodecomposition of surface azo groups was much larger than that initiated by thermal decomposition. Polymer-grafted ultrafine particles thus obtained gave a stable colloidal dispersion in good solvents for the grafted chain. © 1994 John Wiley & Sons, Inc.     

Surface modification of polymers. III. Grafting of stabilizers onto polymer films

Polypropylene, polystyrene, and polyethylene have been grafted with glycidyl acrylate and glycidyl methacrylate. After 5 min of grafting with UV irradiation, polystyrene was extensively grafted to 91% coverage of glycidyl acrylate according to ESCA, while polypropylene was grafted to only 50% coverage. With glycidyl acrylate the grafting depth is estimated to be 0.1 μm for PP and 0.23 μm for PS. Glycidyl methacrylate is grafted in a thinner layer than glycidyl acrylate. The stabilizers 2,4-dihydroxybenzophenone, phenyl 4-aminosalicylate, and 4-amino-2,2,6,6-tetramethylpiperidine were attached to LDPE surfaces containing grafted glycidyl acrylate by opening of the epoxide bond. The reaction between epoxide and stabilizer is diffusion controlled at high concentrations of stabilizer. UV spectroscopy on an LDPE film grafted and reacted with 2,4-dihydroxybenzophenone showed that 227 nmol stabilizer/cm² was bound to the surface.     

Cellulose functionalization via high-energy irradiation-initiated grafting of glycidyl methacrylate and cyclodextrin immobilization

Cotton-cellulose was functionalized using gamma-irradiation-induced grafting of glycidyl methacrylate (GMA) to obtain a hydrophobic cellulose derivative with epoxy groups suitable for further chemical modification. Two grafting techniques were applied. In pre-irradiation grafting (PIG) cellulose was irradiated in air and then immersed in a GMA monomer solution, whereas in simultaneous grafting (SG) cellulose was irradiated in an inert atmosphere in the presence of the monomer. PIG led to a more homogeneous fiber surface, while SG resulted in higher grafting yield but showed clear indications of some GMA-homopolymerization. Effects of the reaction parameters (grafting method, absorbed dose, monomer concentration, solvent composition) were evaluated by SEM, gravimetry (grafting yield) and FTIR spectroscopy. Water uptake of the cellulose decreased while adsorption of a pesticide molecule increased upon grafting. The adsorption was further enhanced by β-cyclodextrin immobilization during SG. This method can be applied to produce adsorbents from cellulose based agricultural wastes.