Stimuli-responsive surfaces are of interest for a multitude of applications such as sensors[1], anti-fouling coatings [2] and cell culture substrates [4]. For the latter, coatings made of thermoresponsive Poly-(N-isopropylacrylamide) pNIPAm microgels have been found to allow reversible switching of cell adhesion upon heating and cooling [3-5]. In these works the microgel layer had to be deposited on the substrate intended for use by printing or spin-coating. Hence, the dimensions and material properties of the substrate can strongly influence the adsorption of the microgel particles. The present contribution will briefly review our efforts in this area. Moreover, the preparation of free standing transferable membranes from cross-linkable microgels will be presented. Such membranes exhibt a thickness of about 100 nm in the dry state and can be transferred to different surfaces. This overcomes problems arising from direct deposition of microgels. The approach is based on the deposition of microgels, containing aromatic moieties, by spin-coating the particles on a sacrificial-polyelectrolyte or gold layer. A suitable comonomer was identified and different comonomer contents were used to make cross-linkable microgels. Atomic force microscopy (AFM) was used to study the surface coverage, topography and the thickness in addition to ellipsometry measurements. Both methods for the characterization of the surface were applied to the dry and wet state to determine the thermoresponsive properties of the layers. The layers are subsequently cross-linked by e-beam irradiation. It is shown that the obtained microgel layers can be used to control ion-flow in electrochemical cells by changing temperature crossing the LCST of PNIPAM.

Smart nanomembranes by electron beam cross-linking of copolymer microgels

255th National Meeting (2018)

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