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。     

(EOXPOYEOX)型嵌段共聚物反胶团形成的影响因素

通过(EOXPOYEOX)型嵌段共聚物有机溶液的水增溶实验研究,探讨了溶剂、聚合物结构、离子强度和温度对增溶水量及临界胶团浓度(CMC)的影响.研究结果表明,正辛醇的加入不仅提高了嵌段共聚物/对二甲苯体系的最大增溶水量(Wo,max),而且也增大了体系的CMC值.lg(1/cmc)随聚合物分子单边EO数X增大而线性递增,表明亲水基EO的内聚能变在胶团化过程中起着重要作用.实验研究范围内,溶液离子强度小于1时,对反胶团的增溶作用有利,一定程度上增大了胶束粒径.反胶团临界浓度的自然对数lnXCMC与温度T成线性关系.胶团化过程是一个自发的放热过程, 并且是一个混乱度降低的熵减过程.     

(EOXPOYEOX)型嵌段共聚物反胶团形成的影响因素

通过 (EO_XPO_YEO_X)型嵌段共聚物有机溶液的水增溶实验研究 ,探讨了溶剂、聚合物结构、离子强度和温度对增溶水量及临界胶团浓度 (CMC)的影响 .研究结果表明 ,正辛醇的加入不仅提高了嵌段共聚物 /对二甲苯体系的最大增溶水量 (W_{o ,max}) ,而且也增大了体系的CMC值 .lg(1/cmc)随聚合物分子单边EO数X增大而线性递增 ,表明亲水基EO的内聚能变在胶团化过程中起着重要作用 .实验研究范围内 ,溶液离子强度小于 1时 ,对反胶团的增溶作用有利 ,一定程度上增大了胶束粒径 .反胶团临界浓度的自然对数lnX_CMC与温度T成线性关系 .胶团化过程是一个自发的放热过程 ,并且是一个混乱度降低的熵减过     

聚合物反胶团萃取研究(Ⅰ)萃取平衡与萃取动力学特性

从聚合物胶团萃取和反胶团萃取的特性分析出发,提出了聚合物反胶团萃取的概念.采用PEO-PPO型嵌段共聚物和有机溶剂组成的聚合物反胶团溶液萃取不同浓度的苯酚水溶液,研究聚合物反胶团萃取平衡和萃取动力学特性.结果表明,随聚合物PPO含量的增加,分配系数和总传质系数都增大;随聚合物浓度的增大,分配系数和总传质系数亦增大;助表面活性剂的加入可以促进聚合物反胶团的增溶作用.     

嵌段共聚物的合成及其组装行为

嵌段共聚物在选择性溶剂中可逆缔合形成以不溶性链段为核 ,溶解性链段为壳的胶束。广泛用作表面活性剂、增溶剂、药物载体和纳米材料等。综述了嵌段共聚物的合成方法 ,着重分析了浓度、温度、嵌段长度、溶剂、添加物及电荷等因素对嵌段共聚物在选择性溶剂中组装行为的影响及其形成机理。展望了嵌段共聚物组装行为的应用前景     

两亲性PNIPAM-b-PVC-b-PNIPAM共聚物的合成与自组装

通过单电子转移-蜕化链转移活性自由基聚合合成不同组成的两亲性聚N-异丙基丙烯酰胺-b-聚氯乙烯-b-聚N-异丙基丙烯酰胺(PNIPAM-b-PVC-b-PNIPAM)三嵌段共聚物,并制备共聚物胶束水溶液,采用荧光光谱、动态光散射、透射电镜、紫外-可见光谱等表征共聚物的临界胶束浓度、胶束结构及温度响应性。结果表明,共聚物可在水中形成以PVC为核、PNIPAM为壳的球形胶束,胶束尺寸在75~135 nm;随着共聚物亲水PNIPAM链段含量的增加,临界胶束浓度增大,而胶束尺寸减小。在升温过程中,胶束溶液的透光率逐渐降低,低临界溶解温度随着共聚物亲水链段含量的增加而增大。     

聚合物反胶团萃取生物活性酶的研究

利用三嵌段聚合物形成的聚合物反胶团进行了萃取生物活性酶的研究,确定了最佳的实验体系.考察了聚合物种类和浓度、助表面活性剂浓度、pH值、温度以及盐浓度等对溶菌酶、胰蛋白酶和α-淀粉酶萃取的影响,为今后在该领域的研究提供了依据.     

新型自组装胶束的制备及其药物释放性能的研究

设计并合成了由亲水链段与疏水链段所组成的新型两亲星形嵌段共聚物.在水溶液中,该星形共聚物能够自组装形成具有核壳结构的纳米胶束粒子.当环境的pH分别为5、7.4、9时,共聚物胶束相应的低临界溶液温度(IESF)分别为32.0、36.6、39.5℃.由于亲水链段具有的温度和pH双响应特性,载药的自组装共聚物胶束也显示出了温度和pH双重响应的药物释放行为.     

Co改性SBA-15分子筛结构稳定性研究

本文以三嵌段共聚物(PEO-PPO-PEO)为模板剂、正硅酸乙酯为硅源,在酸性条件下制备了SBA-15介孔分子筛,采用浸渍法掺杂过渡族Co金属元素对其表面进行修饰。通过FT-IR、BET、和SEM分析对结构进行了表征,结果表明,不同介质不同浓度Co掺杂对介孔分子筛的结构影响较大。     

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.     

Temperature-dependent solubilization of PEO-PPO-PEO block copolymers and their application for extraction trace organics from aqueous solutions

The effect of temperature on naphthalene solubilization in aqueous PEO-PPO-PEO block copolymer solutions has been investigated. Increasing temperature would enhance the apparent solubility of naphthalene in aqueous PEO-PPO-PEO block copolymer solutions. The pseudo-phase model was employed to calculate thermodynamic parameters for naphthalene solubilization in aqueous PEO-PPO-PEO block copolymer solutions.     

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     

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     

Synthesis and self-association in aqueous media of poly(ethylene oxide)/poly(ethyl glycidyl carbamate) amphiphilic block copolymers

New temperature sensitive AB, ABA, and BAB amphiphilic block copolymers consisting of hydrophilic poly(ethylene oxide) and hydrophobic poly(ethyl glycidyl carbamate) blocks were synthesized by anionic polymerization followed by chemical modification reactions. The self-association of the block copolymers in aqueous media was studied by UV-vis spectroscopy and dynamic and static light scattering. The obtained block copolymers spontaneously form micelles in aqueous media. The critical micellization concentration varied from 0.5 to 4 g/L depending on the copolymer architecture and composition. The influence of the temperature upon the self-association of the block copolymers was investigated. The increase of temperature did not affect the value of the critical micellization concentration, but led to the formation of better defined micelles with narrow size distribution.     

Micellization, Interaction and Microenvironment in the Mixed Solution of Pluronics and Surfynol 104 with Nuclear Magnetic Resonance

The micellization, intermolecular interaction and microenvironment of molecular segments in the mixed aqueous solution of PEO-PPO-PEO triblock copolymer (Pluronic? F88, P84 and P123) and Surfynol? 104 (S104) were studied by nuclear magnetic resonance method. The results showed that the addition of S104 decreased the critical micellization temperature of copolymer. When its concentration was 0.5 g/L, the most reduction was up to more than 10℃ for F88, which was most hydrophilic in the selected copolymers. This reduction was caused by the hydrophobic interaction between S104 molecules and PPO segments. The addition of S104 enhanced the hydration of PEO segments most obviously for P123. And S104 slightly increased the hydration of PPO segments before the micellization, but obviously decreased their hydration after micellization, which was attributed to the hydrophobic interaction mentioned above and temperature rising. This effect was most observable for F88.     

Phenylboronic acid as a sugar- and pH-responsive trigger to tune the multiple micellization of thermo-responsive block copolymer

Phenylboronic acid-containing thermo-responsive block copolymer, poly(ethylene oxide)-b-poly(methoxydi(ethylene glycol) methacrylate-co- aminophenylboronic acid ethyl methacrylate) (PEO-b-P(DEGMMA-co-PBAMA)), was employed to investigate the multiple micellization and dissociation transitions. The unique sugar- and pH-responsive properties of phenylboronic acid were interesting to provide two parallel approaches to tune the critical micellization temperature (CMT) and multiple micellization of thermo-responsive block copolymer. The block copolymers were molecularly soluble below 21 °C and underwent micellization above 21 °C at pH 8.7. After glucose was added at 24 °C, hydrophobic phenylboronic acid was changed to hydrophilic boronate-glucose complex and the CMT of the thermo-sensitive block was increased which caused the dissociation of micelles. In parallel, if the solution pH was increased from 8.7 to 11 at 25 °C, micelles were disrupted because of the formation of hydrophilic phenylboronate anion, which elevated the CMT of the thermo-sensitive block polymer. The introduction of phenylboronic acid groups into the thermo-responsive block copolymers provides a novel approach to tune the multiple micellization and dissociation transitions that might have great potentials in biomedical applications.     

Doubly thermo-responsive brush-linear diblock copolymers and formation of core-shell-corona micelles

Doubly thermo-responsive brush-linear diblock copolymer of poly[poly(ethylene glycol) methyl ether vinylphenyl]-block-poly(N-isopropylacrylamide) (PmPEGV-b-PNIPAM) is prepared by RAFT polymerization. The obtained brush-linear diblock copolymer exhibits two lower critical solution temperatures (LCSTs) corresponding to the linear poly(N-isopropylacrylamide) (PNIPAM) block and the brush poly[poly(ethylene glycol) methyl ether vinylphenyl] (PmPEGV) block in water. This brush-linear diblock copolymer undergoes a two-step temperature sensitive micellization. At temperature above the first LCST, the brush-linear diblock copolymer self-assembles into core-corona micelles with the dehydrated PNIPAM block forming the core and the solvated brush PmPEGV block forming the corona. When temperature increases above the second LCST, the polystyrene backbone in the brush PmPEGV block collapses onto the dehydrated PNIPAM core to form core-shell-corona micelles, in which the dehydrated PNIPAM block forms the core, the collapsed polystyrene backbone in the brush PmPEGV block forms the shell and the solvated poly(ethylene glycol) side-chains forms the corona. The effect of the length of the PNIPAM block and the length of the poly(ethylene glycol) side-chains on the thermo-responsive micellization and the size of core-shell-corona micelles is investigated.     

RAFT合成pH和温度响应的双亲水嵌段共聚物

以S-十二烷基-S-′(2-羧基-异丙基)三硫酯(DDATC)为链转移剂,偶氮二异丁腈(AIBN)为引发剂,通过可逆加成-断裂链转移(RAFT)聚合合成了结构明确,窄相对分子质量分布(Mw/Mn=1.27)的聚(N-异丙基丙烯酰胺)-b-聚(N,N-二甲氨基甲基丙烯酸乙酯)(PNIPAm-b-PDMAEMA)双亲水两嵌段共聚物。共聚物的结构通过红外光谱、核磁共振氢谱和凝胶渗透色谱表征。采用透光率法、稳态荧光光谱法、电位滴定和动态光散射考察了PNIPAm-b-PDMAEMA在水中对温度和pH敏感的胶束化行为。结果表明,PNIPAm-b-PDMAEMA具有温度响应性,其水溶液的低临界溶液温度(LCST)为32.3℃,溶液温度高于LCST后发生温度诱导的胶束化,胶束的流体力学半径(Rh)为50 nm左右,Rh随温度升高而稍微增大;PNIPAm-b-PDMAEMA水溶液表现出明显的pH敏感性,25℃时两嵌段共聚物pH诱导胶束化的临界pH=9.8,溶液pH高于临界pH后发生pH诱导的胶束化,胶束的Rh约为31 nm(pH=11.0)。