(3cv) Multiscale Modeling of Liquid Repellency and Self Assembly Process

Interfacial phenomena arise in number of industrially important situations such as liquid repellency, multiphase flow, particulate dispersants, condensation etc., in which the structure of surface plays a key role. Similarly, self assembly lies at the core of many chemically important processes, such as synthesis of silica gel, zeolites, ordered mesoporous materials and Metal organic frameworks, which gives rise to different morphology and porosity in the resulting final structure. My research goal is to design and control the structure, morphology, chemistry and porosity of these materials by studying the phenomena at molecular scale to obtain the basic insight about the chemical and thermodynamic factors that affect these processes. I will highlight my past research effort in these areas and discuss how these studies will be helpful in the design of clean energy and separation technologies.

Surface roughness and chemistry are central to the engineering of materials used in water- and oil repellent applications. The success of these material is determined by their wetting behavior which is assessed by monitoring static and dynamic contact angle phenomena. The primary objective is to construct a methodological framework to study surface properties using molecular simulations and prepare repellent surfaces through experiments using input from molecular modeling. Towards this goal I have developed novel method to study three phase static and dynamic contact angle phenomena. As proof of concept, the methodology has been validated extensively using a simple Lennard-Jones (LJ) fluid in contact with a face-centered cubic LJ crystal surface. Excellent agreement is observed between the static (equilibrium) contact angles obtained by the new method and those reported in the literature. In the experimental part, I am using electrostatic fiber formation technique “electro-spinning” to prepare nonwoven fibrous materials using different polymers. The results obtained from the molecular modeling and experimental study will be discussed.

During my previous postdoctoral research work, I have studied the self assembly of silica-gel formation using multiscale modeling. Understanding mechanism of silica polymerization is an important problem in material science. Here, I have developed a new model of silica polymerization and have studied this using reactive Monte Carlo simulations. In comparison to previous models and simulations, this new model enables study of polymerization reaction at low density and room temperatures. The network evolution from simulation is in excellent agreement with experimental observations. The analysis of simulation results suggest that polymerization occurs in three stages starts with initial oligomerization followed by ring formation, then cluster aggregation and finally gelation. This detailed mechanism provides the opportunity for tailoring the morphology, structure and porosity of the final resulting structure by altering processing conditions.