Rheological Control of Microemulsions via Multifunctional Thermoresponsive Polymer Surfactants

该项目的目的是通过添加新型两亲性温敏聚合物来控制微乳液的流变性能。为了实现随温度升高的受控粘度增加，我们将设计具有链段的共聚物，其显示从亲水性到疏水性行为的LCST转变，然后诱导介观水平上的结构重组。通过系统的变化的类型，数量和位置的温敏块，我们将获得量身定制的聚合物结构，以诱导作为温度的函数的微乳液/聚合物混合体系的受控的复杂的结构和流变行为。另一个主要目的是获得结构相互作用的机制的透彻理解。聚合物表面活性剂将通过受控的自由基聚合来合成，这允许非常可变的方法来实现这种明确的聚合物结构。然后，这些将被纳入生物相容性微乳液和形成的结构将成为研究作为一个全面的温度的函数，通过静态和动态光散射以及小角中子散射（SANS），其中SANS将产生详细的结构信息，通过使用对比度变化。这将成为重要的补充低温透射电子显微镜（低温TEM）的全面介观结构表征。此外，荧光测量将产生关于所形成的网络的连接性的信息。同时，这些网络系统将在整个相关温度范围内通过流变学进行全面研究。特别有趣和具有挑战性的是合成和研究具有两种不同LCST嵌段的聚合物。它们应表现出特别复杂的聚集行为（具有混合或分离的疏水域作为交联点），并具有相应的流变性能。然后，我们的目的是推导出不同的聚合物/微乳液混合系统的聚合物表面活性剂的分子结构之间的详细的相关性，switchably交联的聚集体的介观结构，微乳液的结构和浓度，以及由此产生的宏观流变性能。这样的系统不仅是基本的科学兴趣，但也非常有趣的应用，例如。在制药或化妆品中，特别是当微乳液的高溶解能力与高粘度或甚至凝胶状行为相结合时。

Aim of the project is the temperature control of the rheological properties of microemulsions by the addition of novel amphiphilic thermoresponsive polymers. In order to achieve a controlled viscosity increase with increasing temperature we will design copolymers with segments, that show an LCST transition from hydrophilic to hydrophobic behaviour, which then induces a structural reorganisation on the mesoscopic level. Via a systematic variation of type, number and position of the thermoresponsive blocks we will obtain tailor-made polymer architectures in order to induce a controlled complex structural and rheological behaviour of the microemulsion/polymer hybrid systems as a function of temperature. The other main aim is to gain a thorough understanding of the mechanism of the structural interaction. The polymer surfactants will be synthesized by controlled radical polymerisation, which allows for a very variable approach to such well-defined polymer structures. These will then become incorporated into biocompatible microemulsions and the formed structures will become studied as a function of temperature comprehensively by means of static and dynamic light scattering as well as small-angle neutron scattering (SANS), where SANS will yield detailed structural information by using contrast variation. This will become importantly complemented by cryogenic-transmission electron microscopy (cryo-TEM) for a comprehensive mesoscopic structural characterisation. In addition, fluorescence measurements will yield information regarding the connectivity of the formed network. In parallel, these network systems will be investigated comprehensively by rheology over the whole relevant temperature range. Particularly interesting and challenging will be synthesis and investigation of polymers with two different LCST blocks. They shall exhibit a particularly complex aggregation behaviour (with mixed or separated hydrophobic domains as cross-linking points) with corresponding rheological properties. Our aim then is to derive for the different polymer/microemulsion hybrid systems detailed correlations between the molecular structure of the polymer surfactants, the mesoscopic structure of the switchably cross-linked aggregates, the structure and concentration of the microemulsion and the resulting macroscopic rheological properties. Such systems are not only of fundamental scientific interest but also highly interesting for applications, e g. in pharmacy or cosmetics, especially when the high solubilisation capacity of microemulsions is to be combined with high viscosity or even gel-like behaviour.