Recent advances in synthesis of nanoparticles with anisotropic interactions and sequence-controlled oligomers with diverse chemistries have enabled the rational design of novel nanomaterials for applications in photonics, plasmonics, catalysis, and next-generation computer chips. Designing such functional nanomaterials requires fundamental understanding of the complex interplay between the entropic and enthalpic forces. Molecular simulations techniques have provided us with a tool to elucidate such complex behaviors in systems with intricate interactions and external stimuli; thus, revealing many nontrivial correlations between molecular design of the building block and the resulting complex morphologies having interesting properties. In this thesis, I will demonstrate how entropic forces, which are sometimes overlooked during design strategies, can be used to assemble structures with target properties, where in some scenarios we can pave an efficient kinetic pathway and in other cases we can promote compatibility and mixing homogeneity between the components. The first part of the thesis examines my recent work on nanoparticle assembly kinetics, where we validate that mesophases with intermediate entropies, such as nematic, rotator, and micro-segregated phases can enhance crystallization rates from the disordered phase. Such design rules can be used to steer the assembly away from phenomena like polymorphism and vitrification. Further, I have detailed the computational and experimental efforts that we undertook to provide evidence of a novel “mosaic-like” mesophase orderings in the monolayer systems, that could potentially act as a switch between hexagonal and square structures. The last study describes the industrial collaborative project that was focused on developing a computational framework using atomistic models to rank polymer and salt chemistries with enhanced homogeneity to improve the quality of the features printed through extreme ultraviolet light processing. Overall, the findings in my work can guide future studies for ‘reverse engineering’ target structural properties by predicting suitable system design parameters and explore unique spectral responses of structures having complex morphologies.