两亲性双嵌段共聚物的合成与降解

为改善聚乳酸的亲水性,以辛酸亚锡为催化剂,自制的D,L-丙交酯和低相对分子质量端羟基聚乙烯基吡咯烷酮(PVP)为单体,采用本体开环嵌段共聚合法,制备了两亲性聚乳酸-PVP双嵌段共聚物。考察了原料配比对共聚物的黏均相对分子质量及在磷酸盐缓冲液中的降解规律的影响,并测定了其接触角和吸水率。结果表     

PS-b-PEA嵌段共聚物的合成与表征

采用“活性”自由基聚合的方法合成了不同分子量的苯乙烯和甲基丙烯酸乙酯[polystyrene-block-poly(ethyl methacrylate),PS-b-PEA]嵌段共聚物。并用凝胶渗透色谱(GPC)和红外光谱(FTIR)对所合成的共聚物进行了表征,实验结果显示:在4-羟基-2,2,6,6-四甲基哌啶-1-氧化物自由基(HTEMPO.)和偶氮二异丁腈(AIBN)存在下,苯乙烯聚合反应所得到的聚苯乙烯分子量分布在1.18~1.2范围,分子量随聚合时间的延长而增大(7 200~69 300 g/mol);将该聚苯乙烯溶于甲基丙烯酸乙酯,在(130±2)℃时可以重新引发甲基丙烯酸乙酯的聚合反应,且甲基丙烯酸乙酯的聚合反应具有“活性”聚合的特征,共聚物的数均分子量及分布分别在57 800~107 800 g/mol和1.22~1.26范围,共聚物由FTIR表征显示:在聚苯乙烯接上聚甲基丙烯酸乙酯后,在1 158 cm-1及1 727 cm-1出现其甲基丙烯酸乙酯的特征吸收峰,说明共聚物为嵌段共聚物。     

TEM characterization of diblock copolymer templated iron oxide nanoparticles: Bulk solution and thin film surface doping approach

The morphology of a novel diblock copolymer, poly(norbornene methanol)-b-poly(norbornene dicarboxylic acid), was investigated before and after metal oxide doping by transmission electron microscopy (TEM) using a novel iodine vapor staining method to image the undoped polymer. A lamellar morphology was observed by TEM after staining the undoped diblock copolymer with iodine vapor. Thin film surface doping resulted in a confinement of the iron oxide nanoparticles within the lamellar domains. Spherical nanoparticle aggregates were observed through a bulk solution doping method. It was observed that the particles were templated by the underlying lamellar structure of the copolymer when the thin film surface doping method was used.     

聚氯化铝残渣制备CaFeAl-LDO及其对甲基橙的吸附

采用聚氯化铝生产中的压滤残渣（PACR）制备CaFeAl-LDO吸附剂,对吸附剂的结构、形貌等进行表征,并考察该吸附剂对甲基橙的吸附效果。结果表明,制备的吸附剂焙烧前具有类水滑石的结构,焙烧后其表面变得疏松多孔,有明显的断层及裂痕。BET分析数据显示,CaFeAl-LDO较PACR比表面积增大近1.5倍,FTIR分析也表明CaFeAl-LDO有效融合了Ca-Al和Ca-Fe型吸附剂的特征峰。吸附实验效果表明,CaFeAl-LDO吸附剂最佳焙烧温度为750 ℃,对甲基橙的吸附符合二级吸附动力学模型,吸附后的LDO经高温焙烧后可以循环使用至少5次。     

Synthesis,self‐assembly behavior,and biological application of a new photochromic azo amphiphilic diblock copolymer

Polymer (N,N‐dimethyl‐ethylamine methacrylate)‐block‐poly{6‐[4‐(4‐methoxy phenyl‐azo) phenoxy] hexylacrylate} p(DMAEMA _m‐b‐AZOM _n) was synthesized by successive reversible addition‐fragmentation chain transfer polymerization in the hydrothermal reactor. The products were characterized by hydrogen nuclear magnetic resonance, differential scanning calorimetry, gel permeation chromatography, and ultraviolet and visible absorption spectroscopy (UV‐vis). In H₂O/THF mixture, we found amphiphilic p(DMAEMA _m‐b‐AZOM _n) self‐assembles occurred. p(DMAEMA₇₉‐b‐AZOM₇) self‐assembled into rods, p(DMAEMA₇₉‐b‐AZOM₅) self‐assembled into giant microspheres with rods wind around, p(DMAEMA₇₉‐b‐AZOM₂) self‐assembled into microspheres. Photochromic behaviors of the polymers in different environments were investigated. We found the colors of diblock copolymers in films changed from yellow to orange after irradiation by ultraviolet and visible (UV) light. The rates of trans‐cis photoisomerization in films were almost the same for the three p(DMAEMA _m‐b‐AZOM _n) copolymers. The rates in aqueous micellar solutions were only marginally faster than those in films for all the three diblock copolymers. The observation of a sizable rate difference in different environments for p(DMAEMA _m‐b‐AZOM _n) suggested that a rotational mechanism might be operative for these water‐soluble amphiphilic diblock copolymers. The self‐assembly behaviors of three copolymers and the application of p(DMAEMA₇₉‐b‐AZOM₂) microspheres in biochemistry were investigated in present work. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Polymeric nanoparticles,micelles and polymersomes from amphiphilic block copolymer

Block copolymers are made up of blocks of different polymerized monomers. Among the block copolymers, amphiphilic block copolymers can self-assemble to form nano-sized vehicles, such as micelles, nanoparticles, polymersomes, in aqueous or non-aqueous media. This review describes the synthesis, formation, and major applications of amphiphilic block copolymer and corresponding vehicles in order to provide an overview of the current features of functionalized block copolymers for drug delivery applications.     

ACFs吸附溶液中甲基橙的性能研究

利用扫描电子显微镜(SEM)、比表面分析仪和FTIR对活性炭纤维(ACFs)进行表征,并研究了ACFs对溶液中甲基橙的吸附性能。考察了吸附动力学、pH值、吸附温度及甲基橙溶液初始浓度对吸附性能的影响。实验结果表明,平衡吸附时间选取150 min,在溶液为中性条件下,溶液中甲基橙的去除率最高,溶液pH值为6时去除率达到最大值为93.45%;溶液温度为25℃时,ACFs的吸附效果最好;甲基橙的去除率随着甲基橙初始浓度增加而增大。等温吸附数据符合Freundlich吸附等温模型,吸附反应过程符合Langergren准一级动力学方程。     

二氧化钛柱撑膨润土对染料甲基橙的吸附行为

以sol-gel法制备TiO2溶胶和钇掺杂TiO2溶胶为柱化剂,制备出了TiO2柱撑膨润土和钇掺杂TiO2柱撑膨润土.X射线衍射分析表明经柱撑后的膨润土层间距明显增大,达1.9 nm以上,经500℃煅烧后其层间距稳定在1.8 nm以上.研究了甲基橙在4种TiO2柱撑膨润土上的吸附行为,结果表明4种TiO2柱撑膨润土吸附染料甲基橙的速率和吸附量均较大,其吸附动力学行为均遵循Bangham方程和Langmuir方程所描述的规律.平衡吸附量qe与平衡浓度ρe之间的关系符合Freundlich和Langmuir等温吸附方程.其吸附均为吸热过程,吸附热值在12～17kJ/mol,吸附表现为表面物理吸附和离子交换作用.     

Preparation,surface wetting properties,and protein adsorption resistance of well‐defined amphiphilic fluorinated diblock copolymers

Novel well‐defined amphiphilic fluorinated diblock copolymers P(PEGMA‐co‐MMA)‐b‐PC₆SMA were synthesized successfully by RAFT polymerization and characterized by FTIR, ¹HNMR and GPC. For copolymer coatings, static contact angles, θ, with water (θ_water ≥ 109.5^°) and n‐hexadecane (θ_hexadecane ≥ 68.9^°) pointed to the simultaneous hydrophobic and lipophobic characteristics of the copolymer surfaces. Dynamic contact angle measurements indirectly demonstrated that copolymer films underwent surface reconstruction upon contact with water, which results in a surface with surface coverage of polar PEG units. Moreover, the distinct nanoscale microphase segregation structures were proved by atomic force microscopy (AFM) images. Finally, using bovine serum albumin (BSA–FITC) as the model protein, copolymers exhibited excellent protein adsorption resistance. It is believed that the combination of surface reorganization and nanometer‐scale microphase segregation structure endows the excellent protein resistance for amphiphilic fluorinated copolymers. These results provide deeper insight of the effect of surface reconstruction and microphase segregation on the protein adsorption behaviors, and these amphiphilic fluoropolymers can expect to have potential applications as antifouling coatings in the field of marine and biomedical. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41167.     

Synthesis,characterization, catalytic and splinting activity of nano Ag end capped l‐glutathione bridged amphiphilic diblock copolymer

l ‐glutathione, a naturally occurring environmental friendly amino acid, was used as an initiator towards the ring opening polymerization (ROP) of ?‐caprolactone (CL) followed by the ROP of tetrahydrofuran (THF). The thiol group of l ‐glutathione reduces Ag⁺ ions and chemically bound to the surface of Ag nanoparticles. The ROP of CL was carried out at 160 °C under nitrogen atmosphere in the presence of stannous octoate(SO) as catalyst whereas the ROP of THF was carried out at 45 °C for 24 h in the presence of phthalic anhydride (PAH) as a comonomer. The synthesized homo, di and nano Ag end capped diblock copolymers were characterized by FTIR, DSC, TGA, FESEM, high resolution transmission electron microscope (HRTEM), EDAX, GPC, nuclear magnetic resonance (NMR), Fluorescence and CD. Further the application of diblock copolymer was tested for splinting activity. The catalytic reduction of 4‐nitrophenol (NP) in the presence of nano Ag end capped diblock copolymer was carried out with the assistance of sodium borohydride as a reducing agent and the apparent rate constant (k_app) was determined and compared with the literature values. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43804.     

Starch-graft-poly(methyl acrylate) copolymer: the new approach to synthesis and copolymer characterization

The two-stage method for poly(methyl acrylate) grafting starch using triethylborane and 1,4-benzoquinone has been developed. The first stage was borylation of alcohol groups of starch. The second stage was polymerization of methyl acrylate in the inhibitor - 1,4-benzoquinone - presence accompanied by the S _H 2-substitution at the boron atom. The advantages of developed method were the homogeneity of the process, the high yield of graft-copolymer, the possibility to control of chain length of synthetic polymer, and the absence of homopolymer in the final product. The molecular weight characteristics of starch-graft-poly(methyl acrylate) copolymer was determined by gel-permeation chromatography. The evidence of the graft-copolymer formation was ¹¹B nuclear magnetic resonance data and its glass-transition temperature. The resulting graft-copolymer has an amphiphilic nature and a high thermal stability compared to the corresponding homopolymers (starch and poly(methyl acrylate)). According to the calculated values of the surface Gibbs energy the surface of starch-graft-poly(methyl acrylate) films is characterized as a high-energy surface.     

两亲嵌段共聚物的合成及其自组装研究进展

作者介绍了两亲嵌段共聚物的活性阴离子聚合、基团转移聚合、开环歧化聚合、活性阳离子聚合、活性／可控自由基聚合、缩聚法、嵌段共聚物化学改性法等合成方法,并对其自组装形成聚合物纳米胶束的制备方法、形成机理以及在药物控制释放领域的应用进行了综述,并对其未来发展趋势进行了展望。     

Synthesis and fractionated crystallization of organic-inorganic hybrid composite materials from an amphiphilic polyethylene-block-poly(ethylene oxide) diblock copolymer

Mesostructurally ordered inorganic-organic hybrid composite materials were successfully synthesized by utilizing a low-molecular-weight amphiphilic polyethylene-block-poly(ethylene oxide) (PE-PEO) diblock copolymer as the directing agent. The hybrid composites were formed via the sol-gel reaction of inorganic precursor tetraethoxysilane (TEOS) in an acidic ethanol/water solution with various amounts of PE-PEO. In these composite materials, the hydrophobic PE block of the PE-PEO copolymer forms separate microphase on the nanoscales within the rigid matrix of silica network. The crystallization of the PE block is strictly restricted within the microphase by the rigid silica matrix and takes place through homogeneous nucleation under the nanoscale confinement environment.     

The effect of block lengths on micelle structure in blends of styrene-isoprene diblock copolymer and poly(vinyl methyl ether)

The micellar structure of styrene-isoprene diblock copolymer and poly(vinyl methyl ether) blends was investigated by using small-angle X-ray scattering and transmission electron microscopy techniques. In order to determine the effect of styrene block length on the formation of micellar structure, three sets of diblock copolymers, with near-identical isoprene block molecular weights, but with different styrene block lengths were studied. With modeling based on the polydisperse Percus-Yevick hard sphere fluid model, the structural parameters characterizing the micelles were determined as a function of copolymer concentrations, temperature, and copolymer block lengths. The core radius was found to decrease on increasing the length of styrene block. The degree of swelling of the corona by PVME increased steadily with increasing the styrene block length.     

Chemoenzymatic synthesis of the novel amphiphilic diblock copolymer poly[caprolactone‐block‐(glycidyl methacrylate)] from a bifunctional initiator and its micellization behavior

The chemoenzymatic synthesis of a novel diblock copolymer consisting of a hydrocarbon block of polycaprolactone (PCL) and an epoxy‐based block of poly(glycidyl methacrylate) (PGMA) was achieved by the combination of enzymatic ring‐opening polymerization (eROP) and atom transfer radical polymerization (ATRP). A trichloromethyl‐terminated PCL macrointiator was obtained via Novozyme 435‐catalyzed eROP of ε‐caprolactone from a bifunctional initiator, 2,2,2‐trichloroethanol, under anhydrous conditions. PCL‐b‐PGMA diblock copolymers were synthesized in a subsequent ATRP of glycidyl methacrylate. The kinetics analysis of ATRP indicated a ‘living’/controlled radical polymerization. The macromolecular structure and thermal properties of the PCL macroinitiator and of the diblock copolymer were characterized using NMR spectroscopy, gel permeation chromatography and differential scanning calorimetry. The well‐defined PCL‐b‐PGMA amphiphilic diblock copolymer self‐assembled in aqueous solution into nanoscale micelles. The size and shape of the resulting micelles were investigated using dynamic light scattering, transmission electron microscopy and tapping‐mode atomic force microscopy. Copyright © 2007 Society of Chemical Industry     

Synthesis, characterization and evaluation of amphiphilic diblock copolymer emulsifiers based on methoxy hexa(ethylene glycol) methacrylate and benzyl methacrylate

Linear, amphiphilic diblock copolymers based on the nonionic, hydrophilic monomer methoxy hexa(ethylene glycol) methacrylate (HEGMA) and the hydrophobic monomer benzyl methacrylate (BzMA) of different molecular weights and compositions were synthesized by group transfer polymerization. The molecular weights and comonomer compositions of these copolymers were characterized by gel permeation chromatography and proton nuclear magnetic resonance (¹H NMR) spectroscopy, respectively. Dynamic light scattering on aqueous solutions of the diblock copolymers indicated that all the copolymers formed aggregates whose size increased with the % w/w BzMA composition and with the overall molecular weight of the linear chains. Turbidimetry on 1% w/w aqueous copolymer solutions was used to determine the cloud points, which were found to increase with the composition in hydrophilic units and the linear chain molecular weight. After polymer characterization, xylene/water and diazinon (pesticide)/water emulsions were prepared using the above polymers as stabilizers at 1% w/w polymer concentration and at different overall organic phase/water ratios. At an organic phase/water mass ratio of 4/1, the lower molecular weight (2500 and 5000 g mol⁻¹) diblock copolymers provided stable single-phase o/w emulsions, matching the behavior of commercially available hydrophilic Pluronics.     

A readily modified polyethersulfone with amino-substituted groups: Its amphiphilic copolymer synthesis and membrane application

An amino-substituted polyethersulfone (PES) was synthesized by the polycondensation of a functional monomer bis(3-amino-4-hydroxyphenyl) sulfone with bis(4-fluorophenyl) sulfone. The amine groups incorporated into PES were employed as anchors to immobilize the chain transfer agents of reversible addition-fragmentation polymerization (RAFT). The resultant macro chain transfer agent was used to initiate the polymerization of the hydrophilic monomers N-isopropyl acrylamino (NIPAAm) and N, N-dimethylamino-2-ethyl methacrylate (DMAEMA), respectively. The gel permeation chromatography (GPC) results confirmed the successful synthesis of the amphiphilic copolymers PES-g-PNIPAAm and PES-g-PDMAEMA, and these two copolymers were perhaps the few examples of amphiphilic copolymer synthesized via a radical polymerization from PES main chains. The amino-substituted PES seemed a versatile precursor that showed a potential of functionalization via various strategies including click chemistry, atom transfer radical polymerization and RAFT polymerization. The synthesized amphiphilic copolymers were finally used as additives to improve the hydrophilicity and the filtration performances of PES membranes.     

Synthesis, characterization and phenol adsorption of carbonyl-functionalized mesoporous silicas

Carbonyl-functionalized mesoporous silicas have been synthesized by co-condensation of tetraethoxysilane and varying contents of 3-(trimethoxysilyl)propyl methacrylate in acidic medium with the block copolymer Pluronic 123 as a structure directing agent. The functionalized materials were characterized by PXRD, TEM, SEM, IR, and N₂ adsorption?Cdesorption at 77?K. Adsorption of phenol in aqueous solution on the materials has been investigated. The experimental results showed that carbonyl-functionalized mesoporous silicas possess strong adsorption ability for phenol with interaction of O-H??O?=?C hydrogen bond. The adsorption data are fitted to Langmuir Isotherms and a maximum adsorption capacity calculated from the Langmuir equation can reach 0.87?mmol of phenol/g. The effect of the pH on phenol adsorption has been studied.     

水合氧化铁的制备过程对其吸附甲基橙的影响

以硝酸铁为原料,Na OH溶液为沉淀剂,通过恒p H沉淀法在p H为3~9范围内制得4种水合氧化铁(Fh),通过XRD、表面零电荷时p H(p Hpzc)测定、N2吸附-脱附法对其进行表征,以甲基橙(MO)为模拟污染物比较其吸附性能。结果表明,p H为5时制备的Fh(Fh5)对MO的去除率为92.8%,明显优于Fh3(34.1%)、Fh7(67.4%)和Fh9(53.7%)。4种Fh对MO的吸附规律符合Langmuir方程,为单分子层吸附。另外考察了沉淀剂类型(Na OH、NH3·H2O)和Fe(Ⅲ)浓度对Fh5吸附MO的影响。结果表明,以Na OH溶液为沉淀剂、Fe(Ⅲ)浓度为0.2 mol/L时制备的Fh5具有最佳的吸附性能。