PEO-PPO-PEO嵌段共聚物聚集行为及其在胶团萃取中的应用
文献类型：学位论文
| 作者 | 苏延磊 |
| 学位类别 | 博士 |
| 答辩日期 | 2003 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 中国科学院过程工程研究所 |
| 导师 | 刘会洲 |
| 关键词 | 嵌段共聚物 FTIR光谱 荧光光谱 聚集行为 胶团萃取 |
| 其他题名 | Aggregation Behavior of PEO-PPO-PEO Block Copolymers and Their Application in Micellar Extraction |
| 学位专业 | 化学工艺 |
| 中文摘要 | 聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO)嵌段共聚物作为高分子非离子表面活性剂,可以应用在药物增溶和缓释、废水处理、介孔材料制备和生物大分子分离等诸多领域,已经成为表面活性剂研究的热点之一.该论文主要研究PEO-PPO-PEO嵌段共聚物在水溶液中的聚集行为.使用荧光光谱研究了碱金属卤化物和小分子脂肪醇调控PEO-PPO-PEO嵌段共聚物在水中的聚集行为.胶团萃取工艺中重要的一步操作是从水中分离胶团,实施胶团固定化是一种比较简单的方法.使用海藻酸钠水凝胶包埋PEO-PPO-PEO嵌段共聚物,考察了嵌段共聚物的渗漏过程.升高温度,可以大大地降低释放率.水凝胶颗粒投入到萘的饱和水溶液中,萘被水凝胶萃取.水凝胶中包埋PEO-PPO-PEO嵌段共聚物物,可以大大提高其萃取萘的能力.其中包埋PPO含量高,疏水性强的嵌段共聚物在水凝胶萃取萘的能力大.水凝胶经过干燥脱水、有机溶剂反萃、吸水再生,可以循环再利用. |
| 英文摘要 | Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers are high molecular weight nonionic surfactants. The properties of PEO-PPO-PEO block copolymers receive increasing attention among surfactant study, and their applications in the solubilization and controlled release of drugs, the treatment of water contaminated with polycyclic aromatioc hydrocarbons, the synthesis of mesoporous materials, and the separation of biomacromolecules have been carried out. The aim of the thesis is to investigate the aggregation behavior of PEO-PPO-PEO block copolymers in aqueous solutions and their application in micellar extraction. Temperature-dependent aggregation behavior of PEO-PPO-PEO block copolymers in aqueous solutions has been studied by FTIR spectroscopic technique. The breakdown of hydrogen bonding interaction and the redistribution of electronic cloud are used to explain the temperature dependent wavenumber of the antisymmetric C-H stretching vibration of methyl groups and the C-O-C stretching vibration. The dehydration of PO segments really favors the formation of hydrophobic microenvironment (micellar cores) in aqueous solutions. We observed that the symmetric deformation vibration of methyl groups splits into two bands, one is a hydrated state and the other is a dehydrated state. The relative peak area fractions associated with the hydrated and dehydrated methyl groups of the block polymers are calculated with the curve-fitting method. We obtained quantitative information about the effect of temperature, concentration, polymer composition, and solvent effect on the structural properties of PEO-PPO-PEO block copolymer micelles. Based on FTIR spectroscopic results, during the hydration process, PEO blocks of the block copolymers are hydrated preferentially in a large concentration range, while the PPO blocks are hydrated only in a condition of lower temperature and lower polymer concentration. Effects of addition of alkali halide salts and aliphatic alcohol upon the thermally induced association behavior of PEO-PPO-PEO block copolymers have been investigated using pyrene fluorescence spectrum. The values of micellization enthalpy and entropy of PEO-PPO—PEO block copolymers are increased with an increase of ?-pentanol content in aqueous solutions. The changed values of micellization enthalpy and entropy, due to the addition of ?/-pentanol, for more hydrophilic copolymer are higher than those of more hydrophobic copolymer; this phenomenon is correlated with the composition of PEO-PPO-PEO block copolymers. For more hydrophilic block copolymer, more water must be replaced from the micellar cores during the n-pentanol solubilization process, so that the contribution from the release of water from micellar cores for thermodynamic parameters of micellization would be higher. The I1/I3 ratio of pyrene in aqueous Pluronic PI03 solutions at temperature below the critical micellization temperature (CMT) decreases with an increase of sodium chloride concentration or the volume percent of n-pentanol, which means an increase of the hydrophobic character of PPO blocks. It is the fluorescence evidence that confirms the existence of unimolecular micelle at the temperature below the CMT, When NaCl is dissolved in the solutions, PPO coils would be further contracted to result in a decrease of the exposure of hydrophobic PO groups to water. Due to the hydrophobicity of n-pentanol, a part of n-pentanol molecules would be concentrated in the cores of the unimolecular micelles. The increased hydrophobicity of the PPO blocks would promote the aggregation of unimers into micelles and decrease the CMT. One important step of micellar extraction is to separate micelles from the aqueous solution. The immobilization of PEO-PPO-PEO block copolymers is one of the most simple method. PEO-PPO-PEO block copolymers are encapsulated with sodium alginate hydrogel, the release percentage of the block copolymers from hydrogel as a function of time is measured. The results indicate that the most hydrophobic block copolymer has the lowest release percentage among the samples tested. The release percentage of PEO-PPO-PEO block copolymers can be reduced markedly with increasing temperature. At room, temperature, hydrogel beads were put into saturated naphthalene solution, the naphthalene was extracted by hydrogel. The extraction capacity of hydrogel is enhanced dramatically by encapsulating PEO-PPO-PEO block copolymers. The hydrogel encapsulating the most, hydrophobic copolymer has the largest capacity to extract naphthalene. The alginate hydrogel can be reused through a process of drying, reverse-extraction and regeneration. |
| 语种 | 中文 |
| 公开日期 | 2013-09-16 |
| 页码 | 129 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1372]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 苏延磊. PEO-PPO-PEO嵌段共聚物聚集行为及其在胶团萃取中的应用[D]. 中国科学院过程工程研究所. 中国科学院过程工程研究所. 2003. |
入库方式： OAI收割
来源：过程工程研究所
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。