壳聚糖-O-聚(聚乙二醇甲醚甲基丙烯酸酯)接枝共聚物的ATRP合成及其自组装研究

以十二烷基硫酸钠-壳聚糖复合物(SCC)为起始物,将溴代异丁酸偶联到SCC的羟基上,得到溴代SCC(Br-SCC).以Br-SCC作为大分子引发剂,溴化亚铜、二联吡啶为催化剂,引发聚乙二醇单甲醚甲基丙烯酸酯(MPEGMA)原子转移自由基聚合,得到SCC-O-PMPEGMA;SCC-O-PMPEGMA中十二烷基硫酸钠(SDS)用Tris-2-甲基-2-氨基-1,3-丙二醇(Tris)解复合脱除,最终制备得到壳聚糖-O-PMPEGMA(CS-O-PMPEGMA).用FTIR和1H-NMR对中间产物与CS-O-PMPEGMA进行了表征,结果表明SCC的溴化度可以通过改变溴代异丁酸/SCC的投料比调节,改变MPEGMA/Br-SCC的投料比则可调控PMPEGMA的聚合度.用动态光散射、zeta电位仪以及TEM等手段研究了CS-O-PMPEGMA与肝素钠的复合行为,结果表明随着肝素钠/壳聚糖结构单元摩尔比(X)增加,复合胶束的粒径增大、表面电位降低;当X超过2时,肝素钠与CS-O-PMPEGMA复合形成球形纳米颗粒,其水合半径约44nm,zeta电位为-8.9mV.合成得到的CS-O-PMPEGMA具有规整化学结构,能与聚阴离子复合形成球形胶束,很有希望在基因传递与肿瘤靶向等领域得到应用.     

溴化壳聚糖抗菌敷料的电化学制备及性能

采用电化学两步法快速制备了一种含溴胺结构的自支持壳聚糖抗菌敷料(Chit-Br)。利用场发射扫描电子显微镜(SEM)、能谱仪(EDS)、衰减全反射红外光谱(FTIR-ATR)、碘量滴定、抗菌实验对溴化壳聚糖膜的结构、溴胺(N—Br)含量及抗菌性能进行了表征。结果表明:壳聚糖可通过电极反应原位生成溴化试剂而被溴化,溴化过程同时伴随着对糖单元的氧化。当阳极电量为4.0~20.5C时,所制备的Chit-Br膜中的N—Br含量无显著差异。溴化壳聚糖膜对大肠杆菌和金黄色葡萄球菌均具有优异的抗菌性能,通过破坏细菌表面结构导致细菌死亡。     

原子转移自由基聚合法改性壳聚糖及其抑菌性研究

合成了大分子引发剂(CS-Br)———壳聚糖(CS)接枝2-溴丙酰溴,然后以溴化亚铜与五甲基二乙烯三胺(PMDETA)为催化体系,氯甲基化甲基丙烯酸二甲氨乙酯季铵盐(DMC)为单体,利用原子转移自由基聚合法制备了新材料P(CS-Br-DMC)。重点研究了该材料对白色念珠菌、金黄色葡萄球菌和大肠杆菌的最低抑菌浓度(MIC)、抑菌圈直径及溶血性。同时考察了其在不同时间对三种菌种生长的影响,并且与壳聚糖本身的抑菌性进行了对比。结果表明,该材料比壳聚糖具有更好的水溶性和抑菌性,其对金黄色葡萄球菌的抑菌效果最佳。     

水溶性N,O-羟乙基壳聚糖的合成

在Na OH存在下,以溴乙醇为羟乙基化试剂对壳聚糖进行了改性,得到羟乙基壳聚糖(HECTS);用元素分析法(EA)确定了产物的羟乙基取代度(DS),并以产物的取代度为基准,用四因素三水平正交实验优化了反应的条件;同时,用FT-IR和~1H NMR表征了产物结构,超声辅助直接溶解法评价了产物的水溶性。结果表明,壳聚糖经碱化处理后再用溴乙醇改性,生成的产物为N,O-羟乙基壳聚糖(N,O-HECTS),羟乙基取代度为82.42%及其以上的N,O-HECTS在中性条件就具有较好的水溶性;当n溴乙醇/n壳聚糖单元=5.0,nNaOH/n壳聚糖单元=10.0,反应温度为50.0℃和反应时间为36.0h时,N,O-HECTS的羟乙基取代度可达112.39%。     

基于Diels-Alder点击反应构建壳聚糖-O-聚乙二醇接枝共聚物

通过Diels-Alder(D-A)反应,合成了具有规整化学结构的接枝共聚物,壳聚糖-O-聚乙二醇(CS-O-PEG).D-A反应所需双烯体(呋喃环)通过糠基硫醇与端甲基丙烯酸酯聚乙二醇之间的巯基-丙烯酸酯(thio-acrylate)反应合成得到;马来酰亚胺基丙酸通过活泼酯法偶联到十二烷基硫酸钠-壳聚糖复合物(SCC)羟基上,从而获得亲双烯体.采用红外光谱(FTIR)和核磁共振(1H-NMR)表征了中间产物与最终产物的结构,并用原位核磁监测D-A反应及其逆反应过程.结果表明,聚乙二醇双烯体可在水介质中温和条件下定量接枝到壳聚糖羟基上,反应具有点击特征;同时,聚乙二醇与壳聚糖之间的连接键在高温下(90℃)可通过D-A逆反应而发生断裂.     

多孔壳聚糖接枝聚丙烯酸/钠基蒙脱土复合高吸水凝胶的制备及其对Pb2+的吸附

以十二烷基苯磺酸钠(SDS)胶束为孔模板,过硫酸铵(APS)引发,N,N'-亚甲基双丙烯酰胺(MBA)交联,壳聚糖(CS)与丙烯酸(AA)、钠基蒙脱土(Na-MMT)在水溶液中接枝共聚,成功制备了多孔壳聚糖接枝聚丙烯酸/钠基蒙脱土(CS-g-PAA/Na-MMT)复合高吸水凝胶,提出了SDS胶束致孔机理。扫描电子显微镜(SEM)分析表明,添加SDS的样品,凝胶表面出现多孔结构。通过考察SDS浓度对复合高吸水凝胶平衡吸水倍率和吸水速率的影响,发现当SDS浓度为1.5 mmol/L时,复合凝胶在蒸馏水和生理盐水中的平衡吸水倍率相对于空白样分别提高53.9%和35.3%,初始溶胀速率常数K_is也由空白样的1.2652 g/(g·s) 提高到5.1680 g/(g·s)。多孔结构也使复合凝胶对Pb²⁺的吸附速率加快,在10 min内即可达到饱和吸附量的95%,30 min完全达到吸附平衡。     

胶束增强荧光法测定6-溴萘硫酸钾

多环芳烃化合物广泛存在于汽车尾气、煤焦油和香烟中,具有致癌作用,国内外对多环芳烃的检测方法研究十分活跃,卤代芳烃则是重要的测试项目之一。文献[1,2]分别报道了环糊精诱导室温磷光法测定β-溴代萘、α-溴代萘,文献[3]报道了室温磷光法测定6-溴萘硫酸钾。本法在十二烷基硫酸钠(SDS)胶束体系中用荧光法测定6-溴萘硫酸钾,与文献方法比较,本法简便、快速,具有一定实用价值。1试验部分1.1仪器与试剂日立F-4500型荧光光度计;pHS-3型酸度计。6-溴萘硫酸钾(BNS)标准溶液:1.0×10-3mol·L-1;十二烷基硫酸钠(SDS)溶液:0.1 mol·L-1;缓冲溶…     

溴化甲基咪唑键联壳聚糖的制备及其催化N-羟烷基化研究

在水介质中,3-溴烷基-1-甲基咪唑溴化物与壳聚糖发生反应生成了离子液体键联壳聚糖(IL-b-CS)衍生物.通过红外光谱、核磁共振、X射线衍射和热重等分析技术对离子液体键联壳聚糖衍生物进行了结构表征.以离子液体键联壳聚糖衍生物为催化剂,研究了在无溶剂条件下其对芳香胺和碳酸乙烯酯N-羟烷基化反应的催化性能,讨论了反应条件(催化剂用量、反应物料比、反应温度和反应时间)对其催化性能的影响.     

表面活性剂双水相的性质及其应用 Ⅱ: 表面活性剂双水相在生物活性物质中的应用

测定了胰蛋白酶在表面活性剂双水相中的分配比,检测了分配在双水相中酶的活力及构象变化,并与阴离子表面活性剂十二烷基硫酸钠(SDS)、阳离子表面活性剂溴化十二烷基三乙铵(C_(12)NE)对酶活性及构象的影响进行了对照,结果表明,SDS对蛋白质的变性明显强于C_(12)NE.阳离子表面活性剂过量的双水相体系,简称阳离子双水相,其中的SDS与C_(12)NE由于库仑引力和疏水相互作用力,使得SDS较难被胰蛋白酶吸附,胰蛋白酶在阳离子双水相中的活性没有丧失.其构象亦未发生显著变化.     

壳聚糖嫁接大环席夫碱的合成

以5-溴水杨醛、1,2-二溴乙烷、邻苯二胺和壳聚糖为原料,采用超声波催化法合成了壳聚糖嫁接大环席夫碱,其结构经1H NMR,FT-IR,MS和元素分析确证。     

Preparation of poly(methyl methacrylate) grafted hydroxyapatite nanoparticles via reverse ATRP

Surface-initiated reverse atom transfer radical polymerization (reverse ATRP) technical was successfully employed to modify hydroxyapatite (HAP) nanoparticles with poly(methyl methacrylate) (PMMA). The peroxide initiator moiety for reverse ATRP was covalently attached to the HAP surface through the surface hydroxyl groups. Reverse ATRP of methyl methacrylate (MMA) from the initiator-functionalized HAP was carried out, and the end bromide groups of grafted PMMA initiated ATRP of MMA subsequently. Fourier transformation infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA) and transmission electron microscopy (TEM) were employed to confirm the grafting and to characterize the nanoparticle structure. The grafted PMMA gave HAP nanoparticles excellent dispersibility in MMA monomer. As the amount of grafted PMMA increased, the dispersibility of surface-grafted HAP and the compressive strength of HAP/PMMA composites were improved.     

Controlled pore functionalization of poly(ethylene terephthalate) track-etched membranes via surface-initiated atom transfer radical polymerization

A new method for surface-initiated atom transfer radical polymerization (ATRP) on the technical polymer poly(ethylene terephthalate) (PET) has been developed which allows controlling and estimating the layer thickness of the grafted polymer in the isocylindrical pores of track-etched membranes. After PET surface treatment by oxidative hydrolysis, the bromoalkyl initiator was immobilized on the PET surface in a two-step solid-phase reaction; the isoporous membrane structure was preserved, and the pore diameter was increased from 760 to 790 nm. Poly(N-isopropylacrylamide) (PNIPAAm) was grafted under ATRP conditions from a methanol/water mixture at room temperature. Both monomer concentration and reaction time could be used as parameters to adjust the degree of grafting. Effective grafted layer thickness and its response to temperature were estimated from pure water permeability. All data, especially the high polymer densities (0.37 g/cm3) in the swollen layers at 25 degrees C, indicate that grafted PNIPAAm with a "brush" structure has been achieved. For dry PNIPAAm layer thicknesses on the PET pore walls of up to 80 nm, a temperature-induced swelling/deswelling ratio of approximately 3 had been observed. Reduction of the brush grafting density, via composition of the reaction mixture used in solid-phase synthesis for initiator immobilization, led to an increase of that swelling/deswelling ratio. Further, density and temperature response of the grafted PNIPAAm layers synthesized via ATRP were compared with those obtained in the same membranes by less controlled photografting, leading to lower grafting density and larger gradients in grafted layer density and, consequently, much higher swelling/deswelling ratios (>15).     

Target grafting of poly(2-(dimethylamino)ethyl methacrylate) to biodegradable block copolymers

A series of copolymers composed of methoxy poly(ethylene glycol) and a hydrophobic block of poly(ɛ-caprolactone-co-propargyl carbonate) grafted with poly(2-[dimethylamino]ethyl methacrylate) was synthesized by combining ring opening polymerization, azide-alkyne click reaction, and atom transfer radical polymerization (ATRP). Well-defined copolymers with a target composition and a tailored structure were achieved via the grafting from approach by using a single catalytic system for both click reaction and ATRP. Kinetic studies demonstrated the controlled/living character of the employed polymerization methods. The thermal properties and self-assembly in aqueous medium of the graft copolymers were dependent on their composition. The resulting polymeric materials showed low cytotoxicity toward L929 cells, demonstrating their potential for biomedical applications. This type of materials containing cationic side chains tethered to biocompatible and biodegradable segments could be the basis for promising candidates as drug and gene delivery systems.     

表面引发的原子转移自由基聚合法在聚偏二氟乙烯表面制备可控的聚甲基丙烯酸甲酯刷

采用表面引发的原子转移自由基聚合法(ATRP)在聚偏二氟乙烯(PVDF)表面制备结构可控的聚甲基丙烯酸甲酯刷。通过碱处理和紫外光照溴代的方法,将ATRP引入到PVDF表面; 然后采用ATRP法将甲基丙烯酸甲酯接枝到溴代的PVDF表面。采用傅里叶变换红外光谱和X-射线光电子能谱对改性前后PVDF表面的结构进行了表征。结果表明甲基丙烯酸甲酯成功地接枝到了PVDF表面。     

原子转移自由基聚合(ATRP)在二氧化硅表面接枝中的应用

ATRP方法是在二氧化硅(SiO2)表面接枝聚合物的一种有效方法.通过硅烷偶联剂把ATRP引发剂键接到SiO2表面,然后进行表面ATRP聚合,可以在SiO2表面接枝各种均聚物、嵌段共聚物、超支化聚合物.聚合可以在有机溶剂或水中进行.把ATRP方法同其它聚合方法如氮氧稳定自由基聚合或开环聚合相结合,可以在SiO2表面接枝复杂结构的聚合物如V型嵌段共聚物、梳型共聚物等.SiO2表面ATRP聚合可以通过外加引发剂或外加二价铜来实现聚合可控.     

Multi‐functional poly(vinylidene fluoride) graft copolymers

Poly(vinylidene fluoride) (PVDF) is known for its biocompatibility, piezo and pyro‐electricity, and membrane forming capability. In order to tune its properties, modification through grafting from approach by atom transfer radical polymerization (ATRP) is preferred. Hydrophilic polymers like poly(ethylene glycol) methacrylate, poly(methacrylic acid), poly(dimethylaminoethyl methacrylate) (PDMAEMA), and so forth have been anchored from PVDF backbone in order to make permeation of water molecules through the PVDF based membranes. The successful solution grafting of PDMAEMA chains from PVDF backbone by ATRP resulted appreciable graft conversion and hence its bulk properties showed a significant change. This water soluble graft copolymer shows incredible mechanical and adhesive properties. PVDF‐g‐poly(n‐butyl methacrylate) generates honey‐comb porous film using “breath figure” technique. Recently, they have used further improvement of grafting where model ATRP initiators are anchored using atom transfer radical coupling and used them as macroinitiators for grafting. This approach simplified the grafting reactions even more and enabled successful grafting of a large number of monomers under relatively less drastic conditions with appreciable conversion compared with the previous conditions. This technique has resulted interesting solution properties, ion and electron conducting PVDF, antifouling membrane, super glue and super tough materials, capable of generating metal nanoparticles tunable with pH and temperature. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2569–2584     

Antibacterial poly(ethylene terephthalate) surfaces obtained from thymyl methacrylate polymerization

Thymol, an antibacterial agent was used for the preparation of a methacrylic monomer. The conventional and atom transfer radical (ATRP) polymerizations of this monomer were studied using different conditions. Then, the functionalization of poly(ethylene terephthalate) (PET) films by “grafting from” ATRP using this monomer was investigated. In this aim, a three steps procedure was developed. The surfaces were first treated by NH₃ plasma treatment to incorporate primary amino functions. Then, in a second step, ATRP initiator was grafted by reaction with bromoisobutyryl bromide. Surface initiated ATRP of thymyl methacrylate was performed in solution in the presence of a sacrificial initiator. The efficiency of these reactions was confirmed by X‐ray photoelectron spectroscopy. Wetting properties and surface energy were found to vary systematically depending to the type of functionalization and grafting. The poly(thymyl methacrylate)‐grafted PET surfaces exhibit resistance to bacterial adhesion toward Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus strains. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1975–1985     

结构规整的高密度两亲性接枝聚合物刷的合成及其自组装研究

大分子单体通过两种可控聚合方法, 即开环易位聚合(ROMP)和原子转移自由基聚合(ATRP)的联用, 合成一种新型两亲性接枝聚合物刷. 具有高环张力的降冰片烯单侧链大分子单体norbornene-graft-poly(ε-caprolactone)/Br (PCL- NBE-Br)首先进行ROMP反应, 生成聚合物主链, 每个单体单元上含有一条PCL链和一个溴官能团; 然后用含溴的ROMP聚合物poly(norbornene)-graft-poly(ε-caprolactone)/Br (PCL-PNBE-Br)作为大分子引发剂引发单体2-(dimethyl- amino)ethyl methacrylate)的ATRP反应, 生成结构明确的高密度两亲性接枝聚合物刷poly(norbornene)-graft-poly(ε- caprolactone)/poly(2-(dimethylamino)ethyl methacrylate) (PCL-PNBE-PDMAEMA), 其主链每个单体单元上均含有一条疏水性PCL接枝链和一条亲水性PDMAEMA接枝链. 最后, 研究此类高密度两亲性接枝聚合物刷的自组装行为, 用动态激光光散射(DLS)研究其在混合溶剂(THF/H2O)中的胶束行为, 考察胶束溶液的浓度以及不同长度的亲水性接枝链对胶束尺寸的影响; 利用透射电镜(TEM)观察胶束为球形, 具有类似线团或草莓状的形态.     

Improving the hydrophilic and antifouling properties of poly(vinyl chloride) membranes by atom transfer radical polymerization grafting of poly(ionic liquid) brushes

In this study, poly(1‐butyl‐3‐vinylimidazolium bromide) (PBVIm‐Br) was grafted onto the poly(vinyl chloride) (PVC) membrane surface via a 2‐step atom transfer radical polymerization (ATRP) reaction. Poly(2‐hydroxyethylmethacrylate) (PHEMA) was grafted onto the membrane surface by aqueous ATRP reaction; then, BVIm‐Br was introduced onto the surface of the PHEMA‐modified PVC membrane through traditional ATRP reaction. The analysis of surface chemistry confirmed the successful grafting of PHEMA and PBVIm‐Br on PVC membrane surface, and the grafting density (GD) of PBVIm‐Br gradually increased as the grafting time was prolonged. The modified membrane exhibited a positive charge and significantly enhanced surface hydrophilicity. The static water contact angle of the membrane surface decreased from 92.3° to 51.6° as the GD of the PBVIm‐Br brushes increased. Filtration experiments indicated that the water flux of the modified membrane increased with increasing GD, and their recovered fluxes were more than twice than the original. In addition, the total fouling ratio of the membranes decreased from 89% in M0 to 67% in M5, and most of the fouling was reversible as the GD of PBVIm‐Br brushes increased. These results indicated that the positive charged poly(ionic liquid) brushes featuring hydrophilic properties would have potential applications in membrane separation.     

Length scale heterogeneity in lateral gradients of poly(N-isopropylacrylamide) polymer brushes prepared by surface-initiated atom transfer radical polymerization coupled with in-plane electrochemical potential gradients

We report the preparation and characterization of poly(N-isopropylacrylamide) (PNIPAAm) polymer brushes exhibiting controlled lateral variations in the patchiness of polymer chains. These gradients were achieved through an atom transfer radical polymerization (ATRP) grafting-from approach utilizing surfaces on which the spatial profile of the initiator density was carefully controlled. Initiator density gradients were formed on Au by first preparing a hexadecanethiol (HDT) density gradient, by reductive desorption using a laterally anisotropic electrochemical gradient. The bare areas in the original HDT gradient were then back-filled with a disulfide initiator, (BrC(CH3)2COO(CH2)11S)2. The initiator coverage was characterized by X-ray photoelectron spectroscopy (XPS). Then, surface-initiated ATRP was utilized to transfer the initiator density gradient into gradients of PNIPAAm chain density. Ellipsometry, surface plasmon resonance (SPR), and atomic force microscopy (AFM) were used to characterize these PNIPAAm density gradients. The defining characteristic of the PNIPAAm gradients is the evolution of the morphology from discontinuous mushroom structures at extremely low grafting densities to heterogeneous patchy structures at intermediate grafting densities. The size of the patchy domains gradually increases, until at a high grafting density region, the morphology evolves to a smoother, presumably more extended, structure.