Co-nonsolvency Induced Self-Organization of Thermoresponsive Block Copolymers in Solution and in Thin Films

该研究项目致力于在共溶条件下，在水和有机溶剂的混合物中，具有不同结构的响应性两亲嵌段共聚物（二-、三和星星嵌段共聚物）的自组装。嵌段共聚物，始终包含聚（甲基丙烯酸甲酯）作为永久疏水性嵌段，使用三种不同的温敏嵌段（PNIPAM，PNIPMAM和PNVIBAM），其中亲水性酰胺基团的分子精细结构是系统变化的。将使用RAFT（可逆加成断裂链转移）和可切换链转移剂进行合成。研究的一个特别重点是体相和薄膜中共溶剂诱导自组装的比较。在散装中，依赖于溶剂混合物（水/甲醇）中形成的聚集体的响应块的选择，聚合物结构和溶剂混合物的组成将主要研究，和分子相互作用的开关行为的起源，以及链动力学上的共溶剂的影响将得到阐明。除了荧光相关光谱学，动态光散射和小角度X射线和中子散射将被使用。这些将由光谱测量（拉曼）和非弹性中子散射来补充。在薄膜中，将研究在与来自水和有机溶剂的溶剂混合物的蒸气相接触时也观察到多远的协和行为，以及这种行为在薄膜和溶液中是否/如何不同。此外，它将在薄膜中的嵌段共聚物与基板的相互作用的影响，并与气相上的共溶行为，如果膜厚度起作用的研究。在这些研究中，椭圆偏振法，干涉法和同步加速器GISAXS测量在微流体通道以及中子散射实验在液体和蒸汽细胞将被采用。它还计划从选定的系统，另外与FT-IR光谱和非弹性中子散射实验的薄膜的动力学进行调查。

The research project addresses the self-assembly of responsive amphiphilic block copolymers having different architectures (di-, tri- and star block copolymers) in mixtures of water and organic solvents under cononsolvency conditions. The block copolymers, which consistently contain poly(methylmethacrylate) as permanently hydrophobic block, use three different thermoresponsive blocks (PNIPAM, PNIPMAM and PNVIBAM), in which the molecular fine structure of the hydrophilic amide groups is systematically varied. The synthesis will be carried out using RAFT (Reversible Addition Fragmentation Chain Transfer) and switchable chain transfer agents. A special focus of the investigations is on the comparison of the cononsolvency-induced self-assembly in the bulk phase and in thin films. In the bulk, the dependence of the aggregates formed in solvent mixtures (water/methanol) on the choice of the responsive blocks, the polymer architecture and the composition of the solvent mixtures will be primarily studied, and the molecular interactions which are at the origin of the switching behavior as well as the influence of the cosolvent on the chain dynamics will be elucidated. Apart from fluorescence correlation spectroscopy, dynamic light scattering and small-angle X-ray and neutron scattering will be used. These will be complemented by spectroscopic measurements (Raman) and inelastic neutron scattering. In thin films, it will be investigated, in how far a consonsolvency behavior is also observed in contact with the vapor phase from solvent mixtures of water and organic solvents and whether/how this behavior differs in thin film and in solution. Moreover, it will be investigated in thin films which influence interactions of the block copolymers with the substrate and with the vapor phase have on the cononsolvency behavior and if film thickness plays a role. For these studies, ellipsometry, interferometry and synchrotron GISAXS measurements in microfluidic channels as well as neutron scattering experiments in liquid and vapor cells will be employed. It is also planned to investigate the dynamics of thin films from selected systems additionally with FT-IR spectroscopy and inelastic neutron scattering experiments.