Functionalised nanostructured Polymer Materials
The main aim is the development of polymer materials with improved properties for structural lightweight applications. Our strategy for meeting this goal lies in the targeted addition of nanoparticles to a polymer matrix: e.g. silica nanoparticles provide a polymer with increased resistance to abrasion and heat. Nanoparticles based on carbon (carbon nanotubes, graphenes) can make a polymer stronger and less breakable, leading to promising possibilities in applications in motor vehicles, aircraft and shipbuilding, and in the manufacturing of everyday objects. Nanoparticles are also used in the development of efficient membranes with long-term stability for the separation of materials. In addition to the improved mechanical properties, nanoparticles can provide a polymer with further characteristics, such as increased resistance to chemicals, antistatic properties and electrical and/or thermal conductivity.
In addition to simple polymers as a matrix, our research also deals with copolymers and block copolymers as candidates for the polymer matrix, because fascinating possibilities are arising in this area for linking nanoparticles to particular domains and thus achieving regular arrangements.
Thus there are two main focuses of research: polymer-based nanocomposites and block copolymers.
Polymer-based nanocomposites:
The great challenge in the mixing of nanoparticles in a polymer matrix consists of overcoming the tendency of the nanoparticles to agglomerate. In order to achieve an even distribution of the nanoparticles in a polymer matrix, the nanoparticles are chemically modified. Using controlled polymerisation or polycondensation reactions, nanoparticles are decorated with polymer chains, increasing mixability in a matrix and also the interaction between the filling material and the matrix.
As matrix polymers for example polyamides, polyesters and polyoxazoles are investigated.
Coated carbon nanotubes
Organically coated gold nanoparticles
In cooperation with the Helmholtz University Young Investigators Group “Nanochemistry and Nanoengineering”, work is being carried out on the optimisation of the dispersion of nanoparticles by functionalising the nanoparticle surface.
Part of the work is carried out together with project partners in the framework of the CNT Initiative supported by the BMBF, and in the framework of the EU project HARCANA coordinated by Helmholtz-Zentrum Geesthacht.
Nanochemistry and Nanoengineering
Block copolymers:
Phase diagram for conformationally symmetric diblock melts. The regions of stability for the lamellar, gyroid, cylindrical, spherical and close-packed spherical phases are denoted L, G, C, S and Scp, respectively. The transmission electron micrographs correspond to polystyrene-block-polybutadiene diblock copolymers forming the corresponding morphologies with compositions of S40B60 (lamellar), S25B75 (cylindrical) and S21B79 (spherical), respectively. (The contrast of the schemes is inverse to the TEM pictures).
Block copolymers consist of molecularly defined blocks of thermodynamically incompatible polymer segments, so that phases of nanoscopic size are formed. The fascinating capacity of the block copolymers for self-organisation into highly ordered structures, such as lamellae, cylinders, gyroids or balls, is based upon this. For applications of these nanostructures, such as pattern formation in the nanometre range, nanolithography, templates or even membranes for materials separation, it is of decisive importance to know the conditions that lead to the formation of a certain geometry. Therefore, our focus in this area is on the study of the morphology formation, the influence of changing conditions on the formation of the microstructure and the ability to control these processes. The morphological and mechanical characterisation of the manufactured block copolymers is carried out on thick material as well as on thin films. Part of the work on this takes places in the EU project SELFMEM, coordinated by Helmholtz-Zentrum Geesthacht.
