Responsive Polymer Membranes and Templates
We develop a range of various approaches to fabrication of polymer membranes and templates from polymers, copolymers, block-copolymers and composite materials. Thin films of block-copolymers undergo phase segregation, resulting in various regular structures of lamellar, cylindrical, spherical, or even more complicated shapes. Dimensions of the structures can be determined by the molecular dimensions of the block-copolymers and are of the order of between 5 and 100 nm. This size range is of special interest as for the fabrication of polymer membranes and templates. Using different approaches, including lithographical ones, those structures may be transformed into regular arrays of submicron channels, pores, or domains of electroconductive, light-emitting, magnetic materials, and so forth. Coordination of the particular block with low molecular weight molecules on the first step allows fabrication of organized structures such as a comb-like block copolymer. This morphology is then frozen by cooling the systems below the glass transition temperature. The low molecular weight component is then removed by dissolving in a selective solvent leaving voids and channels. The materials with a regular array of nano-pores fabricated in this way can then be used as membranes or templates. The templates are filled with metals or electroconductive polymers that yield thin films of practical interest for nano-devices and sensors.
We developed a novel method for the fabrication of flexible stimulus-responsive polymer gel membranes (PG-membranes). These membranes are thin porous films made of a cross-linked polyelectrolyte. In our approach, the porous films are formed by the phase separation of polyelectrolyte and a volatile additive. This approach provides the broad possibility of regulating pore sizes and membrane responsiveness.
Figure 1. Stimuli responsive polymer membranes and templates.
The PG-membranes can be prepared on any flat substrate with a low surface roughness (e.g., Si-wafer). Afterwards, the membrane can be transferred (and attached chemically, if necessary) onto various porous or non-porous supports with flat, profiled, and even curved surfaces (e.g., membrane filter, fabrics, chemical sensor, or human skin) for the fabrication of devices with pH-controllable permeability.
- Fabrication of combi-like block-copolymer thin films with the ordered arrays of cylindrical domains;
- Fabrication of non-selective surfaces for orientation and switching of orientation of the block-copolymer films;
- Fabrication of polymer membranes with nanoscopic pores;
- Fabrication of polymer membranes with gradient properties;
- Fabrication of ordered arrays of nanoscopic metallic nanoparticles of various shapes: round clusters, cylinders, lamellas;
- Fabrication of responsive gel membranes.
Group co-operates with:
- Prof. O. Ikkala, Helsinki University of Technology, Finland
- Prof. R. Jérôme, University of Liege, Belgium
- Leibniz Institute of Polymer Research Dresden, Germany