My work focuses on developing and implementing computer programs to study scientific and engineering problems. These range from molecular scale studies of environmental chemistry to large (macroscopic) scale investigations of engineering materials such as polymer nanocomposites. This work complements experimental research in gaining a deeper understanding of the chemistry and physics that govern material properties and chemical processes. This molecular-to-macroscopic understanding is needed for knowledge-based (deterministic) improvement of existing materials and processes, as well as the development of novel materials with unique and desired properties. Specific projects that we are currently involved in, and which are described at www.adm.hb.se/~kib, include hydrocarbon and water phase equilibria (e.g., for dimensioning distillation plants), water penetration into polymer insulation that surrounds electrical cables (and which leads to failure of these cables), growth and properties of carbon nanotubes and multiscale modelling of polymer nanocomposites.