CRC TRR 61 B11 - Molecular imprinting in polyelectrolyte multilayers: Towards selective binding and controlled porosity

Basic data for this project

Description

By combining layer-by-layer (LbL) self-assembly with the concept of molecular imprinting in polymers, we aim at developing molecular imprinting in LbL thin films of polyelectrolytes. The project aims at the fabrication of surface imprinted LbL thin films that have fast and selective binding properties for distinct guest molecules. The introduction of multiple interactions is anticipated to realize the enhanced selectivity. In addition, the incorporation of stimuli-responsive building blocks may lead to smart control over the binding interaction. The goals are to make surface molecular imprinting efficient, highly selective, and controllable; and further to obtain insight into the templating mechanisms and the uptake and release dynamics. For stability enhancement, polyelectrolytes with cross-linkable groups will be used as building blocks. Small template molecules with multifunctional properties, i.e. molecules that provide multi-electrostatic interactions, multi-hydrogen bonds or cooperative interactions with the polyelectrolyte building block, will be employed. The surface imprinted multilayer will be fabricated by using polyelectrolyte with cross-linkable groups on the one hand and a precursor assembly of polyelectrolyte and template molecules on the other hand as building blocks, rendering it with charge selectivity, pH-responsive properties, molecular selectivity and high stability. With such layered imprinting systems available, further developments will be made: First, we attempt to transfer surface molecular imprinting from planar substrates to colloidal particles. This serves to broaden on the one hand the applicability of the systems, and on the other hand the range of physicochemical methods that can be employed to study the systems. Here, in particular, application of dynamic NMR methods is planned. Second, we plan to introduce stimuli-responsive groups to the building blocks of the thin films in order to provide control over the absorption and desorption of guest molecules. The third issue will be a physicochemical characterization with the use of QCM and dynamic NMR methods to determine the in-situ absorption kinetics and provide information about the binding mechanisms, respectively. Further on, the influence of different template molecules on the porosity and permeation properties will be investigated as an approach to develop selective membranes. It is anticipated that these developments will solve the problem of low efficiency in traditional imprinted polymers and finally open a new avenue for the application of the LbL technique and improve the concept of molecular imprinting by avoiding some of its limitations, such as the limited concentration of imprinted sites, and the bulk volume of the polymer matrices which requires long diffusion paths of the imprinted host-molecules.