Project Details
Projekt
Precise nanoscale multiple pore functionalization by wetting-control - for sensing
Subject Area
Polymer Materials
Term
since 2016
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 319805496
Selective sensing and monitoring of dissolved species in aqueous solutions in a decentralized manner is of importance especially in the context of sustainable water management and component recycling, quality control or hazard detection as for example envisioned within the UN Sustainable development goals. Typically, such sensors rely on sophisticated, multistep analyses conducted in specialized laboratories with highly-specialized infrastructure. Here, we aim to explore the opposite strategy by incorporating the sensing element directly within a materials structure. Such a sensor design requires an autonomous function without relying on complex read-out, data transfer, processing or analysis methods. We aim to realise such a sensor concept via a change in wettability of a functionalized porous material triggered by a localized chemical reaction of surface-bound reactive groups with a target analyte. This localized changes in contact angle will trigger a macroscopic wetting transition from a state where the porous material is not infiltrated by the liquid, to a state where the porous material is infiltrated by the liquid containing the target analyte. This wetting transition, in turn, will lead to an easy-to-identify optical readout. Within this proposal, we will investigate the following selective recognition units that trigger a change in wettability upon binding of the analyte:polyelectrolyte brushes changing their conformation and thus surface wettability upon interaction with different ions, Schiff bases and spiropyran which interact with specific ions resulting in polarity change. The optical read-out will be implemented via two platforms. Inverse opals with regular pore structure with dimensions in the range of 200-300nm or multilayer mesoporous films with refractive index contrast provide a photonic crystal that causes constructive interference of light in the visible range. This structural color disappears upon wetting of an inverse opal. Gold nanoparticles embedded within a mesoporous silica film will provide a readout via a shift of their localized surface plasmon resonance upon wetting. Hierarchical architectures, combining both elements will be developed to detect the binding of two different analytes.We aim to demonstrate the general feasibility of this concept using comparable simple surface chemistries based on ion adsorption. The results arising from this project will pave the way for the design of more advanced, sensitive and selective sensing units. The results and insights of the first funding period provide the ideal starting point for the design of such sensors. In these experiments, we capitalized on the use of macroscopic substrate wettability to tailor and direct the local placement of surface chemistry. In the second funding period, we will reverse this strategy and employ localized surface chemistry to tailor macroscopic wettability.
DFG Programme
Research Grants
Cooperation Partner
Professorin Dr. Regine von Klitzing
