波谱学杂志 ›› 2007, Vol. 24 ›› Issue (3): 377-379.

• 博士论文摘要 • 上一篇    

表面活性剂及水溶性功能高分子的NMR研究

作者:刘爱红 导师:刘买利   

  1. 中国科学院 武汉物理与数学研究所,湖北 武汉430071
  • 收稿日期:1900-01-01 修回日期:1900-01-01 出版日期:2007-09-05 发布日期:2009-12-05

NMR Studies on Surfactants and Water-soluble Functional Polymer

Author: LIU Ai-hong Advisor: LIU Mai-li   

  1. Wuhan Institute of Physics and Mathematics,The Chinese Academy of Sciences,Wuhan 430071, Hubei, China
  • Received:1900-01-01 Revised:1900-01-01 Online:2007-09-05 Published:2009-12-05

摘要: 核磁共振(NMR)技术是研究表面活性剂在溶液中聚集状态的一种非常有用的工具,本文运用多种NMR技术研究了几种不同类型表面活性剂及水溶性功能高分子在水溶液中的聚集行为:
1. 季铵盐型双子表面活性剂16-4-16的聚集行为季铵盐型双子表面活性剂N,N′-双(十六烷基二甲基)-α,ω-丁烷溴化铵(16-4-16)分子中联接基团及靠近离子头的质子位于胶束的壳层, 运动受到一定限制. 而距离离子头较远的烷烃链位于胶束的内部,运动相对自由. 与对应的单链表面活性剂十六烷基三甲基溴化铵(CTAB)相比,16-4-16形成的胶束堆积更为紧密. 通过NOESY谱中交叉峰强度的定量计算,认为16-4-16在胶束中分子以上下交错排列的方式形成球形聚集体. 
2. 脱氧胆酸钠与十六烷基三甲基溴化铵的相互作用在脱氧胆酸钠(NaDC)溶液中,NaDC质子H3与其他质子不同,其横向弛豫时间(T2)表现为双指数衰减,表明此质子可能存在两种不同的状态. 实验证明,其它胆酸盐的H3的横向弛豫也呈现双指数衰减. 因此推测在胆酸盐的稀溶液中,3-OH质子和羰基氧之间有可能存在氢键作用,形成了头尾相连的分子对结构. 
在NaDC和CTAB的混合溶液中,两者形成1∶1的混合胶束. 用NOESY和ROESY研究混合胶束的结构,显示CTAB的离子头位于NaDC的羧酸基团附近. 这可能是正负离子之间的静电性相互作用的结果. 
3. 丙烯酰胺/丙烯酸模板共聚物的微结构研究了不同pH值条件下,丙烯酰胺和丙烯酸共聚物分子在水溶液中的聚集形态. 在酸性溶液中,分子内的氢键致使聚集体形成较为紧密的堆积,侧链的苯氧基团运动受阻;随着溶液pH值的增大,丙烯酸电离产生的阴离子使得分子间的静电斥力增大,分子链变得伸展,分子间的氢键作用导致了聚集体体积变大. 当溶液呈强碱性,丙烯酸完全电离,氢键作用力被破坏,分子呈现自由伸展的状态,侧链的苯氧基团运动相对自由.

关键词: 核磁共振, 表面活性剂, 高分子, 胆酸盐, 胶束

Abstract:

Nuclear magnetic resonance (NMR) is an effective method to investigate the microstructure of surfactant micelles and the arrangement of the surfactant molecules in the micellar core. In this dissertation,we studied the aggregation behavior of soluble functional polymer and two kinds of surfactants in aqueous solution by NMR technique. 

1. gemini surfactant 16-4-16

The cationic gemini surfactant of alkanediyl-α,ω-bis(alkyldimethylammonium) bromide is designated as m-s-m,where m and s are the number of carbon atoms in the alkyl chain and the alkanediyl spacer,respectively. The protons of 16-4-16 in the spacer group and a part of hydrophobic protons next to the polar head groups are involved in the surface layer of the micellar core. The hydrophobic protons away from the polar head group are situated internal in the micellar core. The motion of the molecules in the micelles is relatively more restricted than that of their monomeric homologue CTAB. A special arrangement of the molecules in the spherical 16-4-16 micelles is postulated.

2. NaDC and NaDC/CTAB mixed solution
The proton (H3) behaves differently from the other protons in the individual deoxycholate (NaDC) solution. It seems that H3 exits in two states. Its transverse relaxation times obey biexponential decay. We consider that bile salts form head-to-tail molecular pairs via hydrogen bonding between 3-OH and carboxyl oxygen atom in dilute aqueous solution. Furthermore,a 1∶1 mixed micelles form in NADC/CTAB binary aqueous solution. The results of NOESY and ROESY indicate that the polar heads of CTAB are located in the near vicinity of the carboxyl groups of NaDC molecules in the mixed micelles which is due to the strong ionic interaction between these two components.

3. acrylamide/methacrylic acid template copolymer
At quite low pH values,intra-molecular hydrogen bonds between the PAM and PAA blocks lead to compact molecular arrangement and the motion of the phenoxy side chains of the POA blocks is somewhat restricted. With the increase in pH value of the solution,the carboxylic acid gradually dissociates, the electro-static-repulsion of the carboxylic ions and the inter-copolymer hydrogen bonding interactions result in the growth in aggregate size. After the carboxylic acid of the PAA block is completely dissociated in alkaline solution,the electro-static repulsion of the carboxylic ion makes the molecular chain of the copolymer exhibit more outstretched,and the phenoxy side chains have more space to move.

Key words: NMR, surfactant, polymer, bile salts, micelle