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。     

水性涂料

正201604012聚碳酸酯/聚氧乙烯嵌段共聚物及其水性组合物的制备及应用:WO2015 170 374[国际专利申请,日]/日本:Asahi Kasei Chemicals Corporation(Miyazaki,Takayuki).-2015.11.12.-61页.-2014/JP62 270(2014.03.07)题述嵌段共聚物由聚碳酸酯链段和聚氧乙烯链段组成,且共聚物的端基为羟基。其中,聚碳酸酯链段的结构式为(ROCO_2)_m(R表示支化或非支化C_(2-15)脂肪烃、脂环烃、芳香烃;m表示数值);聚氧乙烯链段结构式为     

嵌段共聚物PS-b-P2VP的合成及表征

采用氮氧稳定自由基聚合技术合成了苯乙烯和2-乙烯吡啶嵌段共聚物(PS-b-P2VP),用凝胶渗透色谱(GPC)表征了聚合物的分子量及其分布,用红外光谱表征了其结构,结果表明,在氮氧稳定自由基(HTEMPO.)存在下,用过氧化苯甲酰(BPO)引发苯乙烯聚合,当[HTEMPO.]/[BPO]配比为1.8/1时为最佳比例,在此比例下所制备聚合物PS的分子量分布在1.17~1.36范围内;再将该聚苯乙烯溶于2-乙烯吡啶,在(130±2)℃时可以继续引发2-乙烯吡啶的聚合反应,且2-乙烯吡啶的聚合反应具有“活性”聚合的特征,共聚物的分子量分布范围在1.16~1.35内,分子量在12 930~19 670 g/mol范围。红外谱图说明共聚物为嵌段共聚物。     

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     

用三乙基铝-乙酰丙酮-水三元体系合成聚氧化丙烯及其与氧化乙烯共聚物

氧化烯烃均聚及其共聚物在现代工业中得到了广泛的应用。分子量在几万以下的氧化丙烯和氧化乙烯的嵌段共聚物,是一类非离子表面活性剂;超高分子量(百万)聚氧乙烯,具有凝絮作用和降低流体摩阻的特殊功效,这方面无锡市化工研究所已有成功的研究和生产。但对超高分子量聚氧化丙烯及其共聚物的合成和应用还不多。七十年代初美国报导了氧化乙     

不同拓扑结构PEG-PCL嵌段共聚物的结晶研究

合成了不同拓扑结构的聚乙二醇-聚己内酯(PEG-PCL)嵌段共聚物,共聚物结构分别为AB型线性两嵌段(diblock)、ABA型线性三嵌段(triblock)、AB_2型星形(star shape)嵌段共聚物。通过表征发现嵌段共聚物的分子量与设计的分子量接近,且相对分子量分布窄。通过XRD、DSC、热台偏光显微镜(HSPOM)研究了拓扑结构对共聚物结晶的影响。ABA聚合物中间的PEG亲水链受到两端PCL链段阻碍,其结晶衍射峰最弱。三者的等温结晶速率按AB、AB_2、ABA的速率递减,形成的球晶结构规整度则逐渐增加。     

分子量对两亲性嵌段共聚物PCL-b-PEG结晶与熔融的影响

以聚己内酯-聚乙二醇嵌段共聚物(PCL-b-PEG)为研究对象,用旋涂法制备了PCL-b-PEG薄膜,并采用DSC、XRD和PLM对不同分子量薄膜样品的结晶行为以及形貌进行了系统分析。结果表明:随着分子量的增加,样品的结晶温度先升高后降低,而主要熔融温度逐渐升高;分子量越小,样品的结晶行为与熔融行为越复杂,样品的球晶形貌越不规则;在嵌段共聚物中PEG段可体现自身的结晶行为,但是PCL-b-PEG的总体结晶行为以分子量占比大的PCL为主。     

PO-EO-嵌段共聚物的结构剖析

本文阐述了PO-EO-嵌段共聚物(聚氧丙烯聚氧乙烯嵌段共聚)的结构剖析方法。其中包括化学分析法、色谱分析和光谱分析。采用核磁共振(NMR)可以简单而准确地确定PO-EO-嵌段共聚物的聚合度,根据聚合度可以求出平均分子量。同时,这些方法对指导生产和应用以及对未知同类产品的剖析具有重要的作用。     

用乙烯基吡啶改性苯乙烯-丁二烯-苯乙烯嵌段共聚物

通过采用1,1-二苯基乙烯作为降活剂降低苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)活性大分子的活性,然后用2-乙烯基吡啶进行封端聚合,合成了苯乙烯-丁二烯-苯乙烯-2-乙烯基吡啶多嵌段共聚物,研究了降活剂和单体用量及反应条件对聚合的影响。结果表明,在降活剂用量控制为活性中心的1.0倍(摩尔比)、2-乙烯基吡啶质量分数控制为活性SBS的3%以下、反应温度在60～83℃及反应时间不少于35min时能够制得相对分子质量可控且分布较窄的嵌段共聚物。     

DPE法合成双亲性丙烯酸酯嵌段共聚物及用于颜料分散剂的研究

以1,1-二苯基乙烯(DPE)为分子量调节剂,偶氮二异丁腈(AIBN)为引发剂进行甲基丙烯酸丁酯(BMA)的可控自由基聚合(DPE法)。研究了溶剂、DPE用量及反应温度对于聚合的影响,得到分子量分布较窄(PDI=1.43)的含有DPE半醌式休眠种结构的聚甲基丙烯酸丁酯(PBMA)。以PBMA为引发剂引发甲基丙烯酸二甲氨基乙酯(DMAEMA)聚合,得到分子量分布较窄的(PDI=2.0)双亲性嵌段共聚物(PBMA-b-PDMAEMA)。核磁共振氢谱(1H NMR)测得共聚物组成与GPC测试结果相近。差示扫描量热分析(DSC)测试表明嵌段共聚物在11℃和35℃处有两个玻璃化转变温度。色浆的流变和粒径测试及漆膜性能测试表明,将所得双亲性嵌段共聚物作为酞菁蓝颜料分散剂,可以明显提高酞菁蓝颜料在丙烯酸酯树脂中的分散效率。     

Biodegradable block copolymers with poly(ethylene oxide) and poly(glycolic acid‐valine) blocks

Biodegradable ABA triblock copolymers with poly(ethylene oxide) and poly(glycolic acid‐valine) blocks were synthesized via ring‐opening polymerization of cyclo(glycolic acid‐valine) using Ca‐alcoholates of hydroxytelechelic PEO as the initiator. The L‐valine residue racemized during copolymerization of cyclo(glycolic acid‐valine). The crystallization of the block copolymers decreases with decreasing PEO content in the triblock copolymers and with increasing length of the poly(glycolic acid‐valine) block. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2916–2919, 2002     

Preparation of nano‐sized poly(ethylene oxide) star microgels via reversible addition‐fragmentation transfer polymerization in selective solvents

Poly(ethylene oxide) (PEO) star microgels with a cross‐linked polystyrene core were successfully prepared by reversible addition‐fragmentation transfer polymerization of styrene (St) and divinylbenzene (DVB) with dithiobenzoate‐terminated PEO monomethyl ether (DTB‐MPEO) as macro chain transfer agent in mixtures of ethanol and tetrahydrofuran (THF). The formation of star polymers was affected by polymerization time, solvents and St:DVB:DTB‐MPEO molar ratios. Narrow polydispersed star microgels with high molecular weight were obtained under appropriate polymerization conditions. Transmission electron micrographs suggest that PEO star polymers could form nano‐size spherical micelles in mixtures of water and THF, which further demonstrates the amphiphilic nature of the star polymers. Copyright © 2006 Society of Chemical Industry     

PBT-b-PEO-b-PBT triblock copolymers: Synthesis,characterization and double-crystalline properties

We demonstrated here a facile method to synthesize novel double crystalline poly(butylene terephthalate)-block-poly(ethylene oxide)-block-poly(butylene terephthalate) (PBT-b-PEO-b-PBT) triblock copolymers by solution ring-opening polymerization (ROP) of cyclic oligo(butylene terephthalate)s (COBTs) using poly(ethylene glycol) (PEG) as macroinitiator and titanium isopropyloxide as catalyst. The structure of copolymers was well characterized by ¹H NMR and GPC. TGA results revealed that the decomposition temperature of PEO in triblock copolymers increased about 30 °C to the same as PBT copolymers, after being end-capped with PBT polymers. These triblock copolymers showed double crystalline properties from PBT and PEO blocks, observed from DSC and WAXD measurements. The melting and crystallization peak temperatures corresponding to PBT blocks increased with PBT content. The crystallization of PBT blocks showed the strong confinement effects on PEO blocks due to covalent linking of PBT blocks with PEO blocks, where the melting and crystallization temperatures and crystallinity corresponding to PEO blocks decreased significantly with increment of PBT content. The confinement effect was also observed by SAXS experiments, where the long distance order between lamella crystals decreases with increasing PBT length. For the triblock copolymer with highest PBT content (PBT₅₄-b-PEO₂₂₇-b-PBT₅₄), this effect shows a 30 °C depression on PEO crystals' melting temperature and 77% on enthalpy, respectively, compared to corresponding PEO homopolymer. The crystal morphology was observed by POM, and amorphous-like spherulites were observed during PBT crystallization.     

聚苯乙烯接枝聚氧乙烯两亲接枝共聚物合成的研究

本文采用大分子单体法合成了结构明确的两亲接枝共聚物—聚苯乙烯接枝聚氧乙烯 ( PS— g—PEO) ,通过 IR,NMR和 GPC系统表征了两亲接枝共聚物。通过定性和定量的表征研究 ,结果证明两亲接枝共聚物 PS— g— PEO具有预期的结构     

Synthesis of multiblock copolymers of poly(2‐vinylpyridine) and polyoxyethylene

Telechelic dihydroxy poly(2‐vinylpyridine) (THPVP) samples with different molecular weights were synthesized by using lithium α‐methylnaphthalene as an anionic initiator in mixed solvents of benzene and tetrahydrofuran (THF). Then multiblock copolymers of poly(2‐vinylpyridine) (P2VP) and polyoxyethylene (PEO) were obtained by condensing THPVP and PEO with dichloromethane in the presence of potassium hydroxide. The effects of reaction time, molecular weight of PEO and THPVP, and raw meal ratio PEO/THPVP (w/w) were investigated. The best conditions were found. The copolymers can be purified by water and toluene. The purified copolymers were characterized by infrared (IR) and ¹H nuclear magnetic resonance (¹H‐NMR). The PEO segment content was calculated from the integral curve of ¹H‐NMR spectra. The results showed that these multiblock copolymers were connected through oxymethylene. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1632–1636, 2003     

Crystallization behavior of PEO in blends of poly(ethylene oxide)/poly(2‐vinyl pyridine)‐b‐(ethylene oxide) block copolymer

The crystallization behavior of two molecular weight poly(ethylene oxide)s (PEO) and their blends with the block copolymer poly(2‐vinyl pyridine)‐b‐poly(ethylene oxide) (P2VP‐b‐PEO) was investigated by polarized optical microscopy, thermogravimetric analysis, differential scanning calorimetry, and atomic force microscopy (AFM). A sharp decreasing of the spherulite growth rate was observed with the increasing of the copolymer content in the blend. The addition of P2VP‐b‐PEO to PEO increases the degradation temperature becoming the thermal stability of the blend very similar to that of the block copolymer P2VP‐b‐PEO. Glass transition temperatures, T_g, for PEO/P2VP‐b‐PEO blends were intermediate between those of the pure components and the value increased as the content of PEO homopolymer decreased in the blend. AFM images showed spherulites with lamellar crystal morphology for the homopolymer PEO. Lamellar crystal morphology with sheaf‐like lamellar arrangement was observed for 80 wt% PEO(200M) and a lamellar crystal morphology with grain aggregation was observed for 50 and 20 wt% blends. The isothermal crystallization kinetics of PEO was progressively retarded as the copolymer content in the blend increased, since the copolymer hinders the molecular mobility in the miscible amorphous phase. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Synthesis and characterization of a novel amphiphilic poly (ethylene glycol)–poly (ε-caprolactone) graft copolymers

A series of amphiphilic graft copolymers PEO-g-PCL with different poly (ε-caprolactone) (PCL) molecular weight were successfully synthesized by a combination of anionic ring-opening polymerization (AROP) and coordination-insertion ring-opening polymerization. The linear PEO was produced by AROP of ethylene oxide (EO) and ethoxyethyl glycidyl ether initiated by 2-(2-methoxyethoxy) ethoxide potassium, and the hydroxyl groups on the backbone were deprotected after hydrolysis. The ring-opening polymerization of CL was initiated using the linear poly (ethylene oxide) (PEO) with hydroxyl group on repeated monomer as macroinitiator and Sn(Oct)₂ as catalyst, then amphiphilic graft copolymers PEO-g-PCL were obtained. By changing the ratio of monomer and macroinitiator, a series of PEO-g-PCL with well-defined structure, molecular weight control, and narrow molecular weight distribution were prepared. The expected intermediates and final products were confirmed by ¹H NMR and GPC analyzes. In addition, these amphiphilic graft copolymers could form spherical aggregates in aqueous solution by self-assemble, which were characterized by transmission electron microscopy, and the critical micelle concentration values of graft copolymers PEO-g-PCL were also examined in this article.     

Direct preparation of vesicles from one-pot RAFT dispersion polymerization

Various morphologies including spherical micelles, nanowires and vesicles have been prepared by reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of styrene (St) in methanol using S-1-dodecyl-S -(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (TC)-terminated poly(ethylene oxide) (PEO-TC) and 2,2′-azobis(isobutyronitrile) (AIBN) as chain transfer agent and initiator, respectively. GPC, ¹H NMR, TEM and laser light scattering (LLS) were used to track the polymerization. The results showed that the block copolymers PEO-b-polystyrene (PEO-b-PS) were formed firstly in homogenous polymer solution, and then the spherical micelles were produced via polymerization-induced self-assembling. Continuous polymerization of the PS blocks induced the transition of spherical micelles into other morphologies. The polymerization-induced self-assembling and reorganization (PISR) were induced by chain length ratio increase of PS to PEO blocks. The concentration of St in methanol is also important factor to influence the formation of morphologies.     

Crystallization,morphology, and mechanical properties of poly(butylene succinate)/poly(ethylene oxide)‐polyhedral oligomeric silsesquioxane nanocomposites

The biodegradable poly(butylene succinate) (PBS)/poly(ethylene oxide)‐polyhedral oligomeric silsesquioxane (PEO‐POSS) nanocomposites were prepared by the solution blending and melt‐injection methods. The effect of PEO‐POSS on the non‐isothermal and isothermal crystallization, morphology, as well as mechanical properties of PBS was carefully investigated. The PEO‐POSS nanoparticles dispersed well in the PBS matrix, with the diameters around 30 nm. From isothermal crystallization analysis, the incorporation of PEO‐POSS enhanced the crystallization of PBS due to the heterogeneous nucleation effect while the crystal structure of PBS remained. PBS/PEO‐POSS nanocomposites showed of higher glass transition temperatures than that of neat PBS, attributing to the existence of PEO‐POSS decreasing the flexibility of PBS chains. The elongation at break of the PBS/PEO‐POSS nanocomposites reached the maximum value with PEO‐POSS content of 5 wt%. However, the elastic modulus of PBS decreased after the incorporation of PEO‐POSS. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Non‐isothermal crystallization of poly(ethylene oxide)/silver nanoplate composites

The non‐isothermal crystallization of poly(ethylene oxide) (PEO)/silver nanoplate composites was studied using differential scanning calorimetry. The non‐isothermal crystallization was analyzed by combining the Avrami and Ozawa equations. It was found that the Avrami exponent for neat PEO ranges from 2.51 to 2.53, whereas it ranges from 2.54 to 3.16 for its composites, indicating that the spherical crystal morphology does not change with the addition of nanoplates. However, the rate determination of crystal growth transfers from diffusion to nucleation. The crystallization half‐time showed an increase with the addition of silver nanoplates in PEO, indicating that the overall crystallization rate of PEO decreases with the addition of nanoplates. However, the nucleation activity is larger than unity in the composites and the value increases with an increase in the nanoplate content. This behavior implies that the nanoplates act as anti‐nucleating agents to hinder nucleation. Copyright © 2011 Society of Chemical Industry