Multi-scale study of the dynamics of self-organizing molecular systems

Abstract

Many research groups are studying self-assembly structures via using computational techniques to understand their behavior from a theoretical point of view. Taking different length scales into consideration becomes more important day by day. In this thesis, calculations are performed at the different length scales of meso-scale, quantum scale, and nano-scale. First of all, meso-scale calculations are performed by using the Dissipative Particle Dynamics simulation methodology to obtain the three dimensional morphologies and the corresponding equilibrium structures. These structures are obtained as a collection of beads each of which consists of several atoms. Hence, morphologies varying from spherical and cylindrical micellar to lamellar are obtained. Then, in order to understand origins of interactions between beads forming meso-scale morphologies, quantum mechanical calculations are carried out at the nanoscale by using chemical reactivities and Atoms-In-Molecules theory. The interactions that occur on the interatomic scale are found to control the meso-scale. In addition to meso-scale calculations to obtain morphology, micelles are investigated in terms of their surface-to-volume ratios to the micro-phase separation behavior. Consequently, phase change from spherical to cylindrical micellar and micellar to lamellar phase is observed in surface-to-volume versus concentration plot. Finally, molecular dynamics simulations on the atomic scale are performed to study the dynamics of self-assembled synthetic structures. A reverse mapping algorithm is developed to back fit atomistic detail to morphologies obtained from meso-scale calculations. The detailed structure is soaked into water to study the dynamics of interfacial water since the target structure is superhydrophobic.