Inter- and intramolecular nanomechanical interactions of homo- and heterogenous polymers

• Applicant: Privatdozent Dr. Christian Dietz
• Subject Area: Experimental and Theoretical Physics of Polymers ; Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 467382377

The macroscopic mechanical properties of a variety materials, in particular that of polymers, are determined by their nanomechanical heterogeneity based on the polymer configuration and conformation, chain length and interactions among them. The individual contributions to the nanomechanical properties of a relevant polymer system as model is to be studied in detail in this project. To this end, a multifrequency atomic force microscopy method will be developed that can capture quantitatively the nanomechanical properties at the surface and directly beneath in three spatial directions. Using the first eigenmode of the flexural cantilever vibration the indentation depth of the tip into the sample surface can be controlled while the topography is tracked in the amplitude modulation mode. Through the additional excitation and frequency modulated detection of the second flexural and the first torsional eigenmodes, the conservative and dissipative portions of the tip-sample interaction in two spatial directions can be analyzed. The influence of the chain length and film thickness of thin polystyrene and polybutadiene samples on the nanomechanical properties and thus, on the intermolecular interactions is to be investigated. The comparison of these properties with that of cross-linked and diblock/triblock (co-)polymers of the same components provides valuable information about the intramolecular interactions on the nanoscale. Additionally, the stepwise erosion of the sample surface and the subsequent volume reconstruction of the triblock samples by nanotomography allows for unravelling the structure-property relationship with respect to the nanomechanical properties. Implications of UV radiation on the polymers will be studied by Raman spectroscopy and nanomechanical analysis. Thereby, a relationship between the chemical transformation and mechanical alteration of the block copolymers can be established.

• DFG Programme: Research Grants