Adhesion Mechanisms and Nanomechanics of the Contact Interfaces between TiO2 Nanoparticles in Films and Aggregates - Phase 3

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Our work within the SPP PiKo has progressed to a deep understanding of the nature of the particle contacts at the nanoscale. By means of a combination of Molecular Dynamics simulations and AFM force spectroscopy experiments we could demonstrate that the contact behavior of nanoparticles is related to non-continuum effects where the molecular structure of adsorbed water plays a key role. We could also show how the aggregate size determines the breakage force of agglomerates and were able to unravel the different contributions of rolling and sliding events during the mechanical loading of nanoparticle films. In the third phase of the SPP we seek to broaden the impact of our work in two ways. First, we will apply the knowledge of the force-response of particle agglomerates to predict the behavior of films under complex loading scenarios, including shear strain, relevant to technological applications. Second, we will export our developed coarse-grained (CG) interparticle potentials into Dissipative Particle Dynamics (DPD) formalisms to perform Discrete Element Modelling (DEM) simulations of large aggregate films under complex loading. Our efforts will be directed towards the optimization of a lamination process that enables the deposition of highly porous, FSP-produced nanoparticle films on arbitrary materials substrates by means of a novel layer transfer fabrication process developed in our group. Specifically, we will pursue four main objectives. (1) We will reproduce the experimentally measured mechanical response of whole particle films under controlled loading conditions with newly developed coarse-grained models. From these simulations we will determine the relationships between the film topology and its mechanical response. (2) We will characterize different loading responses under predefined conditions (humidity, particle size distribution, aggregate size, etc.) to investigate the influence of the environment on these mechanical relationships. (3) We will modify the properties of laminated films through different production parameters in a controlled and predictable way using experiments and simulations in parallel (Process Modelling). (4) We aim to transfer our knowledge of the DEM/CG-modelling developed here and other DEM/DPD modelling approaches employed by other SPP partners. Moreover, the applicability of our knowledge to other particle handling technology, such as filtration, will be studied in cooperation with SPP partners.