Keywords

amphiphiles, self-assembly, Gibbs ensemble, simulations, Molecular Dynamics

Abstract

The aim of this dissertation is to investigate self-assembled structures and the phase diagram of amphiphilic molecules of diverse geometric shapes using a number of different computer simulation methods. The semi-realistic coarse-grained model, used extensively for simulation of polymers and surfactant molecules, is adopted in an off-lattice approach to study how the geometric structure of amphiphiles affects the aggregation properties. The results of simulations show that the model system behavior is consistent with theoretical predictions, experiments and lattice simulation models. We demonstrate that by modifying the geometry of the molecules, self-assembled aggregates are altered in a way close to theoretical predictions. In several two and three dimensional off-lattice Brownian Dynamics simulations, the influence of the shape of the amphiphilic molecules on the size and form of the aggregates is studied systematically. Model phospholipid molecules, with two hydrophobic chains connected to one hydrophilic head group, are simulated and the formation of stable bilayers is observed. In addition, (practically very important) mixtures of amphiphiles with diverse structures are studied under different mixing ratios and molecular structures. We find that in several systems, with Poisson distributed chain lengths, the effect on the aggregation distribution is negligible compared to that of the pure amphiphilic system with the mean length of the Poisson distribution. The phase diagrams of different amphiphilic molecular structures are investigated in separate simulations by employing the Gibbs Ensemble Monte Carlo method with an implemented configurational-bias technique. The computer simulations of the above mentioned amphiphilic systems are done in an area where physics, biology and chemistry are closely connected and advances in applications require the use of new theoretical, experimental and simulation methods for a better understanding of their self-assembling properties. Obtained simulation results demonstrate the connection between the structure of amphiphilic molecules and the properties of their thermodynamically stable aggregates and thus build a foundation for many applications of the remarkable phenomena of amphiphilic self-assembly in the area of nanotechnology.

Notes

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Graduation Date

2005

Semester

Summer

Advisor

Bhattacharya, Aniket

Degree

Doctor of Philosophy (Ph.D.)

College

College of Arts and Sciences

Department

Physics

Degree Program

Physics

Format

application/pdf

Identifier

CFE0000695

URL

http://purl.fcla.edu/fcla/etd/CFE0000695

Language

English

Release Date

August 2006

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

Restricted to the UCF community until August 2006; it will then be open access.

Included in

Physics Commons

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