Pluronic-PEI纳米凝胶的制备

<正>聚氧乙烯-聚氧丙烯-聚氧乙烯是一类具有两亲性的三元嵌段共聚物,通常记为:EOx-POy-EOx,商品名为普朗尼克Pluronic,目前BASF公司已经对其实现了商业化生产。通过调节聚氧乙烯PEO和聚氧丙烯PPO的聚合度x、y的比值,可以生产出一系列性能各异的Pluronic产品,以适应不同的生产     

高分子表面活性剂(Ⅱ):合成方法(待续)

正1.4聚乙二醇/聚氧乙烯嵌段基于聚氧乙烯(PEO)的两亲性共聚物代表了迄今为止研究最早且研究最多的高分子表面活性剂,不同组成和不同分子量的PEO和PPO的二、三嵌段共聚物已经作为工业表面活性剂出现在市场上很长一段时间了(如BASF生产的Pluronic),过去的二十年出现了一些关于它们性质的综述~([5,6,8,9,21-23,105])。PEG/PEO聚合物主要通过2种方法合成:乙二醇(EG)的缩合或环氧乙烷开环阴离子聚合。当聚     

利用Pluronic嵌段共聚物的增溶胶束超滤分离技术

增溶胶束超滤 (MEUF)是新型膜分离技术 ,但迄今仅利用普通烷烃链表面活性剂作为其胶束物质 ,由于这些表面活性剂单体相对分子质量低 ,形成的胶束较小 ,不仅难以有效增溶有机分子 ,还可能透过超滤膜造成对水体的二次污染。聚氧乙烯 -聚氧丙烯 -聚氧乙烯三嵌段共聚物 (Pluronics)是一类重要的功能高分子 ,在合适条件下 ,它们在水溶液中聚集生成具有很大内核的胶束 ,这种胶束能有效增溶水溶液中的有机污染物。其次 ,Pluronic共聚物分子单体的大相对分子质量使其容易被超滤膜隔离 ,加上Pluronic共聚物无毒无刺激性 ,因而这类新型功能高分子适合用于增溶胶束超滤方法 ,实现对水体有机污染物的分离。综述Pluronic嵌段共聚物的胶束化、胶束结构、胶束增溶以及在增溶胶束超滤分离技术中的应用     

二元Pluronic嵌段共聚物相互作用 I.PPO嵌段长度相近的P94/L92和F108/L92二元混合水溶液

以I2 作为探针 ,用可见光度方法测定不同浓度比例的P94/L92和F10 8/L92二元Pluronic嵌段共聚物水溶液的临界胶束浓度。实验结果表明 ,这些PPO嵌段长度相近的分子在全部浓度比例范围内都发生相互作用 ,生成了混合胶束。由于这些分子的PEO嵌段长度不等 ,随着具有较短PEO嵌段的L92分子加入 ,P94/L92和F10 8/L92混合胶束外壳的EO基团数减少 ,从而使混合胶束水化度降低     

由聚氧乙烯和聚4'''-酰胺基对四联苯-2,6-二甲酰对苯二胺构筑的OAO形三元嵌段共聚物在N、N-二甲基甲酰胺中的自组装结构模拟

利用耗散粒子动力学模拟方法,研究了由拉胀聚合物聚4''-酰胺基对四联苯-2,6-二甲酰对苯二胺(A)与聚氧乙烯(PEO)组成的OAO形三元嵌段共聚物在溶剂N、N-二甲基甲酰胺(DMF)中的自组装行为,探究了共聚物浓度和链段A的长度对三元嵌段共聚物自组装结构的影响。结果表明,由聚4''-酰胺基对四联苯-2,6-二甲酰对苯二胺(A)与聚氧乙烯(PEO)构筑的线型嵌段共聚物在溶剂N、N-二甲基甲酰胺(DMF)中的自组装将形成形态各异的球状、柱状、毛刷型以及"球刺"状胶束等结构;随着共聚物浓度的增加,球状胶束结构消失,逐渐演变为柱状以及毛刷型结构;随着链段A长度的增加,共聚物形成的球状胶束结构慢慢转变为"球刺"状胶束。     

PEO-PPO-PEO嵌段共聚物在水溶液中的自组装行为及其应用

聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO)嵌段共聚物是一类重要的非离子表面活性剂,在选择性溶剂中可以自组装成多种形貌的介观结构。对PEO-PPO-PEO嵌段共聚物在水溶液中自组装行为进行了综述,介绍了其自组装行为的实验研究技术;阐明了嵌段共聚物构型、分子量、温度、浓度、添加剂等因素对PEO-PPO-PEO嵌段共聚物聚集行为的调控和作用机理;介绍了嵌段共聚物自组装特性的热力学模型、分子模拟及计算机预报等研究方法和研究进展;重点介绍了PEO-PPO-PEO嵌段共聚物在介孔材料制备、药物载体、生物大分子分离、嵌段共聚物修饰等方面的应用。     

PEO-b-PS两亲性嵌段共聚物的合成与表征

以PEO-Br为大分子引发剂,CuBr/2-2’-联吡啶为催化体系,采用原子转移自由基聚合(ATRP)方法制得了一系列分子量可控且分子量分布窄的两亲性嵌段共聚物,通过1H-NMR、GPC、DSC等测试手段对其进行了表征,研究结果表明嵌段共聚物随着聚氧乙烯含量的降低,结晶度(Xc)、结晶熔融温度(Tm)、结晶温度(Tc)降低;当共聚物中聚氧乙烯的含量降为45%时,嵌段共聚物已无结晶现象。     

破乳剂的RSN值与破乳脱水性能的关系

本文以壬基酚胺树脂(PAR)为起始剂与环氧乙烷(EO)、环氧丙烷(PO)聚合,合成一系列PPO、PEO含量不同的嵌段共聚物PAR-PPO-PEO,分别测定了他们的RSN值和破乳脱水效果。结果表明:当PPO数量固定时,RSN值与嵌段共聚物中PEO含量呈线性相关,当PEO含量固定时,RSN值随着PPO数量增加而减小。破乳结果表明:随着RSN值的增加,脱水效果先增加后降低,当PEO含量为30%时对应的RSN值处具有最佳脱水效果。     

Pluronic嵌段共聚物胶束化行为及其胶束增溶

两亲性质的Pluronic嵌段共聚物在合适条件下能自发形成内核很大的稳定胶束 ,其胶束化行为复杂 ,初步的研究深化了对两亲分子自组织机理的认识。实验发现这类胶束具有很强的增溶油溶性物质的能力 ,由于这些分子单体和胶束化行为的特点 ,可望利用这类嵌段共聚物实现在增溶应用场合中的突破。综述Pluronic嵌段共聚物的胶束化行为和胶束增溶规律的当前研究进展     

EO-PPO-PEO嵌段共聚物的表面活性

采用吊环法测量了PEO–PPO–PEO 嵌段共聚物溶液的表面张力,观测到嵌段共聚物溶液的表面张力随着时间延长逐渐降低. 根据嵌段共聚物在气液界面形成分子刷的结构模型, 解释了嵌段共聚物溶液的表面张力随浓度的变化.     

Analysis on the surface adsorption of PEO/PPO/PEO triblock copolymers by radiolabelling and fluorescence techniques

We have examined the adsorption of poly(ethylene oxide)/ poly(propylene oxide)/poly(ethylene oxide) (PEO/PPO/PEO) triblock copolymers (Pluronics?) on dimethyldichlorosilane-treated glass (DDS-glass). The surface concentration of ¹²⁵I-labeled Pluronic F-68(76/30/76) reached a maximum of 0.3 μg/cm² when the bulk concentration in the adsorption solution was 3.0 mg/mL. Above 5.0 mg/ml, the surface Pluronic F-68 concentration started to decrease and reached 0.17 μg/cm² when the bulk concentration for adsorption was 10 mg/mL. The surface concentration of Pluronic F-108 (129/56/129), on the other hand, increased to 4.0 μg/cm² at the same bulk concentration. Fluroscence spectroscopic studies using pyrene suggested that the Pluronic F-68 molecules self-associated at the bulk concentration of 5.0 mg/mL and above. Because the aggregates are expected to expose the hydrophilic PEO segments to water, they may have lower affinity to DDS-glass. Aggregation of Pluronic F-68 also decreases the number of individual Pluronic molecules for adsorption. Pyrene fluorescence in Pluronic F-108 solution, however, suggests that Pluronic F-108 molecules do not form aggregates. It appears that the high surface concentrations of Pluronic F-108 may result from the preferential adsorption of individual molecules in multilayers. This explains the high effectiveness of Pluronic F-108 in preventing protein adsorption and platelet adhesion when adsorbed on to be hydrophobic surface. © 1994 John Wiley & Sons, Inc.     

Synthesis,aggregation and adsorption behaviour of a thermoresponsive pentablock copolymer

Poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) triblock copolymer (Pluronic F127) was modified by introducing poly(N‐isopropylacrylamide) (PNIPAM) at both the PEO ends, and the pentablock copolymer (PNIPAM₄₁–F127–PNIPAM₄₁, PN41) so prepared was characterized using gel permeation chromatography and ¹H NMR spectroscopy. The degree of polymerization of NIPAM blocks at the two ends was 41. The solution behaviour and microstructure of PN41 aggregates in water were examined using UV–visible spectroscopy, micro‐differential scanning calorimetry and small‐angle neutron scattering (SANS) and compared with F127. Two lower critical solution temperatures (LCSTs) were observed for the pentablock copolymer, corresponding to PPO and PNIPAM blocks, respectively. The adsorption of PN41 on thiol‐grafted hydrophobic gold surfaces at various temperatures was investigated using a quartz crystal microbalance. It was found that the adsorption behaviour and mechanism of PN41 were mainly determined by the interactions of the pentablock copolymers with different chain conformations in dilute aqueous solutions at various temperatures. SANS measurements were used to determine the temperature‐dependent structural evolution of polymer micelles in aqueous solution. A NOESY study revealed that above the LSCT of PNIPAM, the interaction of PPO and PNIPAM protons increases and the distance between PPO and PNIPAM decreases. © 2019 Society of Chemical Industry     

Comparison between the self‐assembling behaviors of PLLA‐PEO‐PLLA triblock copolymers and PLLA‐PEO‐PPO‐PEO‐PLLA pentablock copolymers

Poly(L ‐lactic acids) (PLLAs) were grafted to both ends of poly(ethylene oxide) (PEO) to produce biocompatible amphiphilic PLLA‐PEO‐PLLA triblock copolymers. The self‐assembling behaviors of two PLLA‐PEO‐PLLA copolymers in aqueous solutions were examined by Dynamic Light Scattering and Transmission Electron Microscopic techniques. PLLA‐PEO‐PLLA formed spherical micelles, whereas PLLA‐PEO‐PPO‐PEO‐PLLA pentablock copolymers were reported to produce vesicles. It is believed that the PPO segment within the PLLA‐PEO‐PPO‐PEO‐PLLA pentablock copolymers has a dominant role in the formation of vesicles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Evaluation of the permeability and blood‐compatibility properties of membranes formed by physical interpenetration of chitosan with PEO/PPO/PEO triblock copolymers

In order to develop blood compatible membranes with controlled porosity, we have fabricated and examined the properties of physical interpenetrating network (PIN) of chitosan and poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) (PEO/PPO/PEO) triblock copolymers (Pluronics^®). Degree of equilibrium swelling, scanning electron microscopy, and electron spectroscopy for chemical analysis (ESCA) were used to characterize the bulk and surface properties. Vitamin B₁₂ and human serum albumin were used as permeability markers. Platelet adhesion and activation were used to determine the blood‐interaction properties of the PIN membranes. Unlike chitosan membranes that were nonporous, the chitosan‐Pluronic PIN membranes were highly porous with the pore size, depending on the type of incorporated Pluronic polyol. ESCA results showed a significant increase in the ? C ? O? signal of C1s spectra on the PIN membranes that correlates with the presence of PEO chains on the surface. The permeability coefficients of vitamin B₁₂ and albumin were higher in the chitosan‐Pluronic PIN membranes than in the control. The number of adherent platelets and the extent of activation were significantly reduced on the chitosan‐Pluronic PIN membranes. The decrease in platelet adhesion and activation correlated positively with the PEO chain length of the incorporated Pluronic polyols. The results of this study show that chitosan‐Pluronic PIN membranes offer a blood‐compatible alternative with a higher‐molecular‐weight cutoff for use in hemodialysis and related applications. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1274–1284, 2001     

Mechanical properties–morphology relationships in nano‐/microstructured epoxy matrices modified with PEO–PPO–PEO block copolymers

Epoxy‐based blends containing poly(ethylene oxide)‐co‐poly(propylene oxide)‐co‐poly(ethylene oxide) (PEO–PPO–PEO) block copolymers with different PEO/PPO molar ratios have been investigated in order to analyze the effect of the generated morphologies and interactions between components on the mechanical properties of the blends. Mechanical, morphological and dynamic mechanical analyses indicate that the observed increase of flexural modulus can be related to the decrease of free volume. In modified systems that remain miscible, an increase of flexural modulus, strength and fracture toughness can be observed. Also, macrophase‐ and microphase‐separated systems show an increase of fracture toughness but not of flexural modulus and strength at low contents of block copolymers. Copyright © 2007 Society of Chemical Industry     

PEO-PPO-PEO嵌段共聚物温敏特性及其影响机制的分子模拟

以Pluronic P85为例,采用全原子分子动力学模拟方法研究了单链嵌段类共聚物PEO-PPO-PEO在不同溶剂中的温敏性相转变行为及其影响机制。分子模拟结果显示当Pluronic P85溶解在水溶液和极性有机溶剂（甲醇）中时,升温导致PPO和PEO与水或甲醇分子间氢键断裂、使得溶剂化壳层被破坏而释放出水或甲醇分子,Pluronic P85发生构象塌缩,呈现反向温度响应特性。当Pluronic P85溶解在非极性有机溶剂（甲苯）中时,升温导致分子热运动加剧而削弱Pluronic P85链分子内相互作用,使其在甲苯中的构象更加舒展,呈现正向温敏特性。分子模拟结果还展现了PEO和PPO链段的溶剂化效应随温度的变化及其对于聚合物构象的影响,对于此类聚合物的分子设计和应用提供了理论依据。     

Preparation,morphology and sonication time dependence of silver nanoparticles in amphiphilic block copolymers of PEO with polystyrene or PMMA

Composite materials comprising arrays of silver nanoparticles in amphiphilic copolymers have been prepared by sonochemically enhanced borohydride reduction of precursor silver nitrate (AgNO₃). The precursor was incorporated into the cores of polymeric micelles formed from block copolymers of polystyrene (PS) or poly(methyl methacrylate) (PMMA) with poly(ethylene oxide) (PEO). The copolymers were synthesised with varying hydrophobic block lengths from a PEO macroinitiator by atom transfer radical polymerization (ATRP). UV/visible spectroscopy was used to confirm the formation of elemental silver and the effect of sonication time on the appearance of the silver nanoparticles was determined. The growth was faster than when gold nanoparticles are formed in comparable block copolymers. Nanoparticles formed in copolymers with PMMA blocks were more stable to agglomeration than when polystyrene was used. Electron microscopy revealed the morphology of the nanocomposites which confirmed that both block copolymers are vehicles for the formation of well-defined films containing nanoparticulate silver. However, AgNP formation shows some significant differences from previous reports of gold NP containing materials formed under similar conditions.