摘要
选用具有不同碱金属反离子(Na+、K+、Cs+)的C3对称低聚酰胺超分子为研究体系,结合同步辐射X射线小角散射和透射电子显微镜技术,研究碱金属反离子对C3对称低聚酰胺超分子多级自组装的影响.研究表明具有不同碱金属反离子的C3对称低聚酰胺超分子都能在水溶液中自组装成管状结构,这些管状结构在反离子为Na+的溶液中会进一步有序排列成中心正交相,在反离子为K+和Cs+的溶液中排列成六方相.碱金属反离子通过其与C3对称低聚酰胺分子末端羧酸根基团吸附程度的不同来改变管状自组装结构的表面带电量,从而调节甚至改变超分子多级自组装结构,为进一步深入理解离子效应并利用离子效应调控自组装有序结构提供了思路.
The effect of alkali metal counterion(Na+,K+,Cs+)on hierarchical self-assembly of C3-symmetric oligoamide supramolecules was studied by Synchrotron radiation X-ray small angle scattering and transmission electron microscope.The C3-symmetric molecules with three-armed aromatic oligoamide and different alkali metal counterions are denoted as P7(COONa)3,P7(COOK)3 and P7(COOCs)3.The experimental results show that the C3-symmetric molecules can self-assemble into tubular structures,which will further aggregate in aqueous solution to form a centered rectangular phase in P7(COONa)3,or a hexagonal phase in P7(COOK)3 and P7(COOCs)3.The centered rectangular phase formed by P7(COONa)3 has a higher degree of order and the adjacent tubular structures become closer compared with the hexagonal phase formed by P7(COOK)3 and P7(COOCs)3.Though the hexagonal phase formed by P7(COOCs)3 gives a higher degree of order than that formed by P7(COOK)3,they have the similar symmetry and comparable distances between adjacent tubular structures.Therefore,by changing the counterion from Na+to K+or Cs+,a phase transition from a centered rectangular phase to hexagonal phase can be achieved.In addition,the electron-density maps show that the fine structure of tubular aggregates will change slightly when the counterion changes from K+to Cs+,which manifests the increase of the diameter of water channel in the tubular structures.The phase transition mentioned above may result from the different surface charge of tubular structures,as the adsorption capacity of counterions for the terminal carboxylate group in the C3-symmetric oligoamide will decline when the conterion changes from Na+to Cs+due to the increasing ionic radius.This kind of hierarchical self-assembly of ordered superstructure constructed by C3-symmetric oligoamide not only has the advantages of easy modification and structural stability,but also can be manipulated by simply changing the counterion,and thus has great application potential in drug delivery,tissue repair,etc.
作者
黄伟恒
魏升慧
黄宁东
李良彬
王道亮
Wei-heng Huang;Sheng-hui Wei;Ning-dong Huang;Liang-bin Li;Dao-liang Wang(National Synchrotron Radiation Lab,University of Science and Technology of China,Hefei 230029;Hefei Institute for Public Safety Research,Tsinghua University,Hefei 230088)
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2019年第7期702-709,共8页
Acta Polymerica Sinica
基金
国家自然科学基金(基金号21574123,51703117)资助项目
关键词
离子效应
碱金属反离子
C3对称低聚酰胺
超分子自组装
X射线小角散射
Ionic effect
Alkali metal counterion
C3-symmetric oligoamide
Supramolecular self-assembly
X-ray small angle scattering
