The study of polymers in solutions as well as bulk melts is a well established field that has been the topic of much research over the past few decades. In recent years, the spotlight has shifted in favor of multi-component polymer blends and composites, and is specifically directed at tailoring their behavior by controlling interfacial characteristics. The properties of such heterogeneous polymer systems are taken advantage of in myriad uses ranging from high mechanical strength and barrier property applications to bio-inspired and biomimetic materials, and considerable interest has been generated in industry as well as in the scientific community. In particular, designed polymeric and colloidal nanostructures constitute a majority of the currently viable applications of nanotechnology (official funding by the US Govt. exceeding $1 billion for 2007), with examples that include the use of nanocomposites in car parts, stain resistant garments and light-weight beer bottles. However, to completely fulfill the exciting promise of novel hybrid materials, a fundamental comprehension of nanoscale behavior is essential. The focus of my proposed research is on employing computer simulations to provide a molecular understanding of the nanometer level attributes that dictate macroscopically observed properties in heterogeneous polymer systems. Using molecular modeling and statistical mechanics, the specific-interaction driven behavior of macromolecules will be investigated, especially focusing on the structure and dynamics of multi-phase and multi-component polymer systems. Different kinds of heterogeneities will be probed, including dissimilarities between constituent segments of the polymer chains, and variations in morphological features such as spatial restrictions that arise in the form of non-bonded attraction to adjacent surfaces and the presence of multiple phases (polymer/surface, polymer/solvent or polymer/polymer blocks or blends). The aims of the molecular modeling approach are twofold: first, to contribute quantitative and qualitative predictions that complement empirically motivated experiments and synthesis protocols; second, to provide a nanoscale perspective of structure-property relationships in the inhomogeneous materials that are increasingly important in today's world. The research will synergistically impact the fields of chemical engineering and materials science (polymer surfaces and interfaces), energy research (electrolytes for fuel cells) and biological engineering (paradigms for membrane proteins, molecular design of biomimetic heteropolymers). The ultimate goal is to elucidate and derive more insightful approaches to polymer bio- and nanotechnology.