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.     

PS—b—PEO—b—PS三嵌段共聚物的结晶形态和微相分离——（Ⅰ）PEO含量及分子量的影响

采用偏光显微镜和透射电镜研究了PS-b-PEO-b-PS三嵌段共聚和折结晶形态和微相分离,重点讨论了PEO含量和分子量的影响,实验发现,当共聚物中的PEO分子量低至6000、含量低于42%时,均有球晶生成,且随着PEO含量的升高,球晶形态变得更加完善,TEM结晶显示,当PEO分子量为1000含量分别为93%和91%时,形成以PEO为连续相,PS为分散相的微相分离结构,但当PEO含理降低到77%时,发生了相反转,PEO变为分散相,PS变为连续相,当PEO分子量为6000,含量为42%时,形成了以PS为连续相,PEO为分散相的微相分离结构,所有的分散相都有球形或近似球形的形貌,在PEO的分子量为2000,含理为18%,34%时,发现了层状微相分离结构,同时我们还发现,pH=6.0的磷钨酸水溶液是该类嵌段共聚物的有效染色体系。     

CHR/PVC共混增容研究

以聚2－乙烯基吡啶和聚环氧乙烷多嵌段共聚物（P2VP－b－PEO）为增容剂，研究了氯醚橡胶（CHR)和聚氯乙烯（PVC）之间的共混，考察了增容剂用量、PVC／CHR配比、增容剂组成、增容剂中P2VP链段长度对共混物机械性能的影响。发现2％－3％的多嵌段共聚物能够很好地增容CHR／PVC共混体系，多嵌段共聚物中PEO链段含量越高、P2VP链段越长，增容效果越好。     

聚乙烯基吡啶与聚环氧乙烷多嵌段共聚物增容剂的制备

α－甲基萘锂作为引发剂利用阴离子聚合得到2－乙烯基吡啶的遥爪双羟基低聚物（P2VP），然后以二氯甲烷作偶联剂与聚环氧乙烷（PEO）反应制备P2VP和PEO多嵌段共聚物，考察了反应时间对偶联反应的影响，并对共聚物进行了IR和^1H－NMR表征，由^1H-NMR谱的积分曲线得到了共聚物中PEO链段质量分数。     

Pluronic嵌段共聚物胶束作为靶向药物载体

聚氧乙烯 聚氧丙烯 聚氧乙烯 (PEO PPO PEO)三嵌段共聚物 (商品名为Pluronics)在水溶液中能自发生成多分子聚集的胶束 ,这些胶束主要以疏水的PPO嵌段为内核 ,PEO嵌段环绕在外构成外壳 ,这种胶束可以有效地增溶油溶性药物。Pluronic嵌段共聚物无毒、无刺激、无免疫原性 ,胶束外壳的PEO嵌段能阻止血小板的聚集。胶束尺寸和病毒相仿 ,其大小适合在体内传输。初步尝试表明 ,胶束表面嵌上合适的抗体可以将增溶了模型药物的Pluronic胶束定向输送到动物脑部 ,从而提高了药效 ,降低了副作用。实验表明 ,Pluronic嵌段共聚物胶束可能成为将多种药物导向特定部位的有效载体。     

均聚物调控的PS-b-P4VP薄膜的微相分离形貌

分别以聚丙烯酸(PAA)和聚氧化乙烯(PEO)与苯乙烯与4-乙烯基吡啶二嵌段共聚物(PS-b-P4VP)进行溶液共混并且旋涂成膜,采用原子力显微镜(AFM)研究了这两种均聚物对PS-b-P4VP薄膜微相分离形貌的调控作用。结果表明,PAA与P4VP链段之间强烈的氢键作用使得P4VP链段对PS链段的热力学排斥作用增强,当PAA质量分数为10%时,PS分散相区以规则的柱体垂直分布于由P4VP/PAA链段相互溶解所形成的连续相基体中。对于PS-b-P4VP/PEO共混体系,共混薄膜形成了PEO/P4VP分散相以柱状形态垂直分布在以PS链段聚集区为薄膜连续相基体中的微相分离形貌,由于PS链段无法在PEO/P4VP柱状微区上方形成覆盖,导致共混薄膜表面出现许多孔洞,孔洞底部伴有PEO链段部分结晶形成的锥状突起。随PEO含量增加,孔洞直径增大,孔洞底部的锥状突起也增大。     

高分子表面活性剂(Ⅲ):性能及应用(待续)

正2大分子表面活性剂的流变学尽管已有大量关于两亲性共聚物的合成和自组装的出版物,这些体系的流变学到目前为止尚未进行广泛研究。研究最多的体系是AB二嵌段和ABA或ABC三嵌段(遥爪)共聚物,其中亲水嵌段B由PEO或PAA组成,疏水嵌段由聚苯乙烯或脂肪烷基链组成~[442-444]。这些聚合物形成黏弹性溶液,根据聚合物的组成和架构,这类黏弹性溶液在一定的临界浓度转变为凝胶。含有     

PEO嵌段分子自组装研究新进展

综述了近年来多醚链(PEO)嵌段分子自组装的研究进展,阐述了不同形状的化合物与其自组装结构的关系,展望了这类多醚链嵌段分子自组装研究体系的潜在应用价值及其发展方向。     

PS-b-PEO为分散剂的苯乙烯悬浮聚合

采用活性负离子聚合技术设计并合成了聚苯乙烯(PS)-聚环氧乙烷(PEO)嵌段共聚物(PS-bPEO),并以此为分散剂进行苯乙烯悬浮聚合。分析了PS-b-PEO中PS嵌段的相对分子质量及PEO嵌段的质量分数,并考察了PS-b-PEO中PEO嵌段的质量分数、用量(PS-b-PEO中PEO嵌段占苯乙烯单体的质量分数)和搅拌速率对苯乙烯悬浮聚合颗粒特征的影响。结果表明:成功合成了PS嵌段相对分子质量为5 000,PEO嵌段质量分数为3.5%~27.3%的PS-b-PEO;PEO嵌段用量相同时,随着PEO嵌段质量分数的增加,苯乙烯悬浮聚合得到的PS颗粒粒径逐渐增大且分布变宽;以PEO嵌段质量分数为5.0%的PS-b-PEO为分散剂时,PEO嵌段用量由0.05%增加到1.20%,PS颗粒粒径逐渐减小且分布变窄;搅拌速率由220 r/min增加到570 r/min,悬浮聚合仍能稳定进行且PS颗粒粒径减小。     

嵌段共聚物PEO—PPO—PEO增韧环氧树脂的研究

采用嵌段共聚物PEO—PPO-PEO对环氧树脂进行增韧改性。结果表明,PEO—PPO—PEO对环氧树脂具有较好的增韧改性作用,PEO—PPO—PEO／EP／MeTHPA体系的冲击强度随着嵌段共聚物含量的增加而增大,而对拉伸强度影响较小。当F38质量分数为20％时,固化物的冲击强度能提高190％,而拉伸强度仅下降6．2％。TG测试结果表明,PEO—PPO—PEO的加入对环氧固化物的热性能影响不大。     

The Synergism Effect Between Sodium Dodecylbenzene Sulfonate and a Block Copolymer in Aqueous Solution

The synergistic behavior of sodium dodecylbenzene sulfonate (SDBS) with poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) block copolymer was studied using surface tension measurements. The surface tension of single and mixed solutions of SDBS and the block copolymer in this study was measured at different concentrations and at 25 °C. The critical micelle concentration (CMC) of these solutions was determined from the surface tension measurements. The SDBS gives higher CMC values than those of the block copolymer. The results show that the CMC value of SDBS decreases as the molar ratio of SDBS increases in the mixture solution with the block copolymer. The surface parameters of adsorption and micellization for single and mixed solutions were investigated. The results show that the surface and micellization properties of SDBS were improved as a result of mixing with the block copolymer. The mole fractions in the micelles and interaction parameters of the mixed solutions were calculated. The foam stability of single and mixed solutions at 25 °C was determined. The results show that the SDBS has more foam stability than the block copolymer and the foam stability increases as the molar ratio of SDBS increase in mixed solution of it with block copolymer.

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。     

A simple method for creating nanoporous block-copolymer thin films

We introduce a simple method to create block copolymer films with controlled porosity. We show that the pore structure can be varied over a broad range of length scales not obtainable in homopolymer blend films. The morphology is a random two phase kinetically trapped structure that is not limited by the equilibrium block copolymer structure. The morphology is obtained through blending homopolymer poly(4-vinylpyridine) (P4VP) with block copolymer polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and then removing the homopolymer P4VP by washing with ethanol. The structure obtained prior to washing (which templates the nanoporous structure) is stabilized in the kinetically trapped morphology during spincoating and is not obtainable from either homopolymer blends or the pure block copolymer. When PS/P4VP blend solutions in tetrahydrofuran were spincoated at 25% relative humidity, continuous films with raised P4VP nanodomains were formed due to a preferential affinity of the spinning solvent for polystyrene. In a similar manner, when PS-b-P4VP/P4VP block copolymer/homopolymer solutions were spincoated, the P4VP homopolymer was solubilized in the P4VP block domains during spincoating, suppressing macro-phase separation. The film morphology is generated at the air surface and then propagates through the film, resulting in P4VP nanodomains oriented vertically to the substrate. In the resulting films, the size of P4VP nanodomains were varied by increasing the amount of P4VP homopolymer. The subsequent extraction of P4VP homopolymer from the PS-b-P4VP/P4VP blend films in ethanol resulted in nanopores with a distribution of length scales. The morphology of these materials makes the films potentially suitable for a range of applications such as anti-reflective coatings, nanoporous membranes and low-k materials. An illustrative example of an anti-reflective coating will be presented.     

Transformation of self‐assembled structures from spherical aggregates in solution to a network structure on a two‐dimensional surface

Self‐assembled films of brush‐like amphiphilic copolymers with varying hydrophobic contents (fc₁₂, 10–90 mol %) were prepared on glass slides. In addition, the surface tension and contact angles of solutions of these copolymers were also investigated. By combining the data obtained investigating the morphologies of the films, with the micropolarities, dimensions, and morphologies of the copolymer aggregates in solution phase, it was attempted to illustrate how the self‐assembled structures would adapt to a change in their surrounding environment from a three‐dimensional space in the solution phase into a two‐dimensional solid surface. The copolymer chains underwent inter‐ and intramolecular hydrophobic association simultaneously in the solution phase. When fc₁₂ was increased, the stronger hydrophobicity led the side‐chains that were attached to the same backbone to become packed together, and this intramolecular association caused the copolymers to form smaller and more compact spherical aggregates. The solutions of these smaller and more compact spherical aggregates exhibited a lower surface tension and better wetting behavior on glass surfaces. In addition, these solutions ultimately formed thinner and more orderly network‐based porous films on glass surfaces. The observations described in this report revealed that the copolymer assemblies exhibited a morphological transformation from spherical aggregates in solution to a network structure when the copolymer became confined to a solid surface. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41945.     

Visualization of block copolymer distribution on a sheared drop

We have visualized a fluorescently-labeled poly(styrene-b-methylmethacrylate) (NBD-PS-b-PMMA) block copolymer on the surface of a polymethylmethacrylate (PMMA) drop in a polystyrene (PS) matrix. Confocal microscopy revealed that the block copolymer distributed uniformly on the drop surface before deformation. However, in shear flow the copolymer concentration was higher at the tips and edges of the drop. Visualization of drop deformation using a counter-rotating apparatus showed enhanced drop deformation for a drop with block copolymer resulting in larger area generation. Drops with block copolymer showed widening even for shear strains exceeding 10, in contrast to bare drops, which first widened and then shrank. These results agree qualitatively with the observed distribution of fluorescent block copolymer. Copolymer concentration is highest in the regions of high curvature, where lowering interfacial tension should be most effective in retarding drop retraction. Block copolymer on these highly curved surfaces is found to be very effective since the exact theory for zero interfacial tension by Cristini fits our drop widening results well.     

Homo- and mixed polymer brushes prepared by surface-grafting of asymmetric non-sticky/sticky diblock copolymers and their stimuli–responsive behaviors

We synthesize a non-sticky/sticky diblock copolymer, poly[styrene-b-3-(trimethoxysilyl)propylmethacrylate], to produce polymer brushes using the grafting-to technique. Uniform coatings of the polymer brushes are efficiently produced because of the multiple reactive groups offered by the sticky block, and the surface coverage and nanoscopic morphology of the brush layer are adjusted by varying the concentrations of the immersion polymer solutions and the immersion time of the substrate. The nanoscopic pattern of the polymer brushes is subsequently utilized to produce mixed polymer brushes. The resulting homo- or mixed polymer brushes change their nanoscopic morphology in response to external stimuli of temperature and solvent. The results indicate that grafting of the asymmetric non-sticky/sticky block copolymer is an efficient method for producing a surface of polymer brushes with nanoscopic chemical heterogeneity.     

Simple and facile synthesis of aryl benzoates from stabilized arenediazonium tetrafluoroborate using a recyclable polymer-supported benzoate ion

Temperature-responsive P(NIPAM-co-HMAM)-b-PEO-b-P(NIPAM-co-HMAM) triblock copolymers were synthesized by an atomic transfer radical polymerization (ATRP) method without freeze?Cpump?Cthaw cycles. The composition, structure, and molecular weight of the synthesized block copolymer were characterized by ¹?H NMR and GPC. The phase transitions induced by temperature for different copolymers in dilute aqueous solutions have been studied using transmittance measurements, laser particle size measurements, viscosity analysis, and surface tension measurement, which showed that the HMAM content and the PEO (or PEG) chain length in the synthesized triblock copolymer affects the copolymer??s lower critical solution temperature (LCST). The micellization behavior of each temperature-responsive triblock copolymer was investigated by fluorescence probe measurements and transmission electron microscopy (TEM), which showed that the triblock copolymers form stable micelles above the LCST. The introduction of the HMAM component and the formation of micelles represent the first steps in the development of an injectable gel that forms in situ through chemical and physical crosslinking.     

High-throughput preparation of complex multi-scale patterns from block copolymer/homopolymer blend films

A simple, straightforward process for fabricating multi-scale micro- and nanostructured patterns from polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP)/poly(methyl methacrylate) (PMMA) homopolymer in a preferential solvent for PS and PMMA is demonstrated. When the PS-b-P2VP/PMMA blend films were spin-coated onto a silicon wafer, PS-b-P2VP micellar arrays consisting of a PS corona and a P2VP core were formed, while the PMMA macrodomains were isolated, due to the macrophase separation caused by the incompatibility between block copolymer micelles and PMMA homopolymer during the spin-coating process. With an increase of PMMA composition, the size of PMMA macrodomains increased. Moreover, the P2VP blocks have a strong interaction with a native oxide of the surface of the silicon wafer, so that the P2VP wetting layer was first formed during spin-coating, and PS nanoclusters were observed on the PMMA macrodomains beneath. Whereas when a silicon surface was modified with a PS brush layer, the PS nanoclusters underlying PMMA domains were not formed. The multi-scale patterns prepared from copolymer micelle/homopolymer blend films are used as templates for the fabrication of gold nanoparticle arrays by incorporating the gold precursor into the P2VP chains. The combination of nanostructures prepared from block copolymer micellar arrays and macrostructures induced by incompatibility between the copolymer and the homopolymer leads to the formation of complex, multi-scale surface patterns by a simple casting process.     

Nanopatterns of poly(styrene-block-butyl acrylate) block copolymer brushes on the surfaces of exfoliated and intercalated clay layers

We report a study of poly(styrene-block-butyl acrylate) (PSBA) block copolymer brushes on the surfaces of intercalated and exfoliated silicate (clay) layers. The PSBA/clay nanocomposite was synthesized by in situ atom transfer radical polymerization (ATRP) from initiator moieties immobilized within the silicate galleries of the clay particles. Transmission electron microscopy (TEM) analysis showed the existence of both intercalated and exfoliated structures in the nanocomposite. Block copolymer brushes on the surface of exfoliated or intercalated clay layers were found to create nanopatterns after treatment in different solvents. For the block copolymer brushes after treatment in THF, uniform collapsed brush layers are observed. After treatment in acetone, a selective solvent for PBA, wormlike surface aggregates are observed. After treatment in methanol, a precipitant for both of the blocks, micelles as well as wormlike aggregates can be observed. Furthermore, the polymer brushes tend to aggregate together and change their nanopatterns at an elevated temperature.     

Behavior of aqueous solutions of poly(ethylene oxide-b-propylene oxide) copolymers containing a hydrotropic agent

The effect of the hydrotropic agent, sodium p-toluenesulfonate (NaPTS), was evaluated on the micelle formation process and on phase behavior of aqueous solutions containing poly(ethylene oxide-b-propylene oxide) (PEO–PPO) copolymers. We have studied monofunctional diblock copolymers coupled with hydrocarbons groups (R—PEO—PPO—OH and R—PPO—PEO—OH, where R length is linear C₄ and C_12–14). The critical micelle concentration (CMC) and critical micelle temperature (CMT) values of the aqueous copolymers solutions were obtained from both surface tension versus concentration plots and the dye solubilization method. The influence of the hydrocarbons groups length and PPO segment position in the structure of the copolymers were also analyzed. The same measures were obtained for the aqueous solutions of hydrotropic agent which, in turn, also presented molecular aggregation. The presence of the hydrotropic agent in the aqueous copolymers solutions altered the surface tension of these solutions and the occupied molecular area per copolymer molecule at air–water interface and CMC and CMT values of the copolymers. On the other hand, the aggregation points and the surface tension of the NaPTS solutions were dependent on the copolymer structure and composition. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2459–2468, 1998