【作者】 李晶；

【导师】 吴飞鹏； 王尔鑑；

【作者基本信息】 中国科学院研究生院（理化技术研究所） ， 有机化学， 2009， 博士

【摘要】 水溶性疏水缔合聚合物,由于其独特的溶液性质和缔合行为,已成为超分子研究的重要对象,具有重要的理论和应用价值。本论文合成了一种新型可聚合两亲化合物4-(2-(丙烯酰氧基)乙氧基)苯亚甲基三乙基溴化铵(AEBA)。它具有很强的自组装能力,适用于构筑特定架构的分子集合体和聚合物。为此,以两亲化合物AEBA为基础,合成了多种不同功能的疏水缔合聚合物,详细研究了它们的水溶液性质、疏水缔合作用和聚集体微结构;并提出利用AEBA单体与其他亲水单体构成的微多相共聚合新体系,制备高性能疏水缔合聚合物的新方法。1.设计并合成了一种新型具有自组装功能的可聚合两亲化合物4-(2-(丙烯酰氧基)乙氧基)苯亚甲基三乙基溴化铵(AEBA),它易溶于水,具有很强的自缔合能力和对外界刺激(pH值、盐浓度)的响应性。宏观溶液性质表明AEBA具有表面活性和增溶作用,它的最小助溶浓度(MHC)约为0.05 M。通过AEBA分子缔合行为和聚集体微结构的研究发现,AEBA在水溶液中逐步缔合形成堆砌状(stack-type)聚集体结构,临界缔合浓度约为1.5×10-3 M。AEBA分子聚集体的尺寸随浓度增大而逐步增长。2.研究了单体AEBA与阴离子表面活性剂十二烷基硫酸钠SDS水溶液体系中,两亲分子间的缔合作用、相变化过程和囊泡的形成。实验结果表明,AEBA的加入大大促进了SDS的分子间缔合,使SDS的临界胶束浓度CMC大幅度下降。随着AEBA / SDS摩尔比例的提升,溶液中出现分子聚集体结构“胶束-囊泡-实心微粒”的变化,同时伴随溶液“透明-半透明-混浊”的转变。AEBA / SDS在特定比例条件下,形成囊泡状聚集体,并通过聚集体内AEBA分子的聚合反应锁定了囊泡结构,得到了具有很高稳定性的聚合囊泡。这种复合体系为中空纳米材料的制备提供了一种简便方法。3.合成了一种阳离子两亲均聚物P(AEBA)。它具有很高的自缔合能力和盐敏响应性。宏观溶液性质的研究表明,均聚物P(AEBA)在清水中呈现聚电解质的性质,而在盐水中具有聚皂的性质。微观结构的研究十分有趣的发现,两亲聚合物P(AEBA)在水溶液中自缔合形成稳定的珍珠项链(pearl-necklace)状聚集体,随着无机盐的加入,这种项链状聚集体结构中的小球尺寸增大,数量减少,而链长缩短,最终形成中空球型聚集体。首次在实验上完整直观的演示了聚电解质分子聚集体结构“coil-globule”演变过程中存在珍珠项链状中间结构,印证了前人理论推断的结果,具有理论和应用价值。而随聚合物浓度的增加,在清水和盐水中产生了两种不同的分子间缔合聚集体结构,表现出截然不同的宏观溶液性质。4.通过微多相共聚合新体系,合成了系列AEBA改性疏水缔合聚丙烯酰胺P(AM/AEBA),共聚物结构中少量单体AEBA (≤3 mol%)以微嵌段的形式无序分布在大分子亲水主链上。共聚物P(AM/AEBA)在水溶液中显示了很强的疏水缔合作用和增粘效果。当聚合物浓度超过临界缔合浓度CAC时,分子间缔合形成交联网状结构,占有较大的流体力学体积,从而引起溶液粘度迅速上升。聚合物链的微结构(疏水嵌段的含量和长度)和分子量是决定共聚物P(AM/AEBA)疏水缔合作用和增粘效果的主要因素。通过控制聚合反应前体系中AEBA分子聚集体的数量和尺寸,可以获得最佳的增粘效果。这种由自组装功能单体构成的微多相共聚合新体系,可取代传统的胶束共聚合体系,制备具有微嵌段结构特征的高性能疏水缔合聚合物,同时也为其他具有微嵌段结构的功能聚合物的制备提供了一种简便又环保的合成方法。5.利用上述微多相共聚合新体系,合成了一系列新型AEBA改性阳离子絮凝剂共聚物P(AM/DMC/AEBA)。得到的共聚物中,单体AEBA (≤3 mol%)以微嵌段的形式无序分布在AM和DMC构成的大分子亲水主链上。通过高岭土污水模拟体系的絮凝实验表明,AEBA的微嵌段结构大大增强了高分子链间的疏水缔合作用和架桥能力,使共聚物表现出良好的絮凝分离效果。依据初步结果,可以期望利用这种微多相共聚合新技术,合成更多高性能的共聚物絮凝剂。更多还原

【Abstract】 Water soluble hydrophobically associating polymers have become an important subject in supermolecule field due to their unique solution properties and association behaviors. In this thesis, a novel polymerizable cation amphiphilic compound, 4-(2-(acryloyloxy) ethoxy) benzyl tri-ethyl ammonium bromide (AEBA), was synthesized. It has strong capacity for self-assembly. AEBA can be used to construct the molecular assembly and polymers with desired architecture. Based on this amphiphilic monomer AEBA, several kinds of novel hydrophobically associating polymers with different functions were constructed. The solution properties, hydrophobic association behaviors and aggregate microstructures were studied in detail. A new microhetergeneous copolymerization system composed of AEBA and other hydrophilic monomers was proposed to prepare high performance hydrophobically associating polymers.1. A novel polymerizable amphiphilic compound with self-assembly ability, 4-(2-(acryloyloxy) ethoxy) benzyl tri-ethyl ammonium bromide (AEBA), was designed and synthesized. It exhibits good water solubility, strong self-association ability and response to extra-stimulation (pH, salt). The macroscopic solution properties indicate the surface activity and solubilization of AEBA. Its minimum hydrotrope concentration (MHC) locates near to 0.05 M. The studies of self-association behavior and aggregation microstructure demonstrated that AEBA molecules associate gradually into stack-type aggregates conformation. The critical association concentration CAC is at 1.5×10-3 M. The aggregate size of AEBA increases with concentration.2. The intermolecular association, phase transformation and vesicle formation of AEBA / SDS mixture system were investigated. The results show that addition of AEBA significantly promotes the intermolecular association and decreases the CMC of SDS. With an increase of AEBA / SDS molar ratio, a series of structure transformation“micelle-vesicle-solid particle”occurs, accompanying with the change of the solution appearance (“transparent-semiopaque-turbid”). At a certain AEBA / SDS molar ratio, these two amphiphilic compounds associate into vesicles. High stable polymerized vesicles can be obtained by intra-aggregate AEBA polymerization. Obviously, it is a facile method to prepare hollow nanomaterials.3. A cation amphiphilic homopolymer P(AEBA) was synthesized. It has high self-association ability and response to salinity. The macroscopic solution properties demonstrated that P(AEBA) behaves as polyelectrolyte in pure water but in salt solution it is similar to polysoap. It is very interesting to find that P(AEBA) spontaneously associates into pearl-necklace-like aggregates conformation in pure water. With the addition of salt, the size of the necklace beads increases while their numbers and the necklace length decrease. Finally, the necklace-like aggregate associates into a hollow globule conformation. It should be noted that the pearl-necklace-like aggregate conformation and the aggregate size transformation are theoretically and practically important. It first provides a visualized intermedia aggregation state of such type in the“coil-globule”transformation process for polyelectrolyte, which was suggested by early theoretic predict. Furthermore, with the increase of polymer concentration, two distinct aggregate structures were observed, which induced different solution properties.4. A series of AEBA modified hydrophobically associating polyacrylamides were synthesized using new microhetergeneous copolymerization system. The copolymer P(AM/AEBA) containing a small amount (≤3 mol%) of AEBA exhibits strong hydrophobic associative interactions and thickening efficiency in aqueous solution due to the microblock-like structure of AEBA. As the copolymer concentration above CAC, P(AM/AEBA) forms network structures with large hydrodynamic volume based on intermolecular association, which result in a rapid viscosity enhancement. The polymer chain microstructure (content and length of hydrophobic microblock) and molecular weight are both the main factors to determine the hydrophobic association interactions and thickening effect of P(AM/AEBA). The optimal results can be obtained by properly regulating the number and size of AEBA aggregates before copolymerization, as well as reaction conditions. It should be pointed out that this new microhetergeneous copolymerization system composed of self-assembly monomer can be used to substitute the traditional micellar copolymerization system to prepare high performance hydrophobically associating polymers with microblock structure characteristic. It also provides a facile and environmental friendly method for synthesis other functional polymers with microblock structure.5. A novel microhetergeneous copolymerization technique was used to prepare a series of AEBA modified cation flocculant copolymers P(AM/DMC/AEBA) in aqueous solution. The resulting copolymers contain a small amount (≤3 mol%) of AEBA monomer which distributed as microblock manner along the copolymer chains. The flocculation experiments demonstrated that the microblock-like structure of AEBA promotes the intermolecular hydrophobic interactions and bridge-linkage actions of the macromolecules, resulting copolymers exhibits good flocculation and separation effect. Based on the preliminary results obtained, it is reasonable to expect that flocculants copolymers with higher performance can be synthesized using this novel microhetergeneous copolymerization technique.更多还原