Electrostatically-driven self-assembly of polyelectrolytes and colloidal tetrapods

electrostatics;self-assembly;Monte Carlo;free energy;dielectric;polarization;like-charge attraction;cluster algorithm;rod;tetrapod;hypersphere;quaternion

Sinkovits, Daniel

关键词: electrostatics;    self-assembly;    Monte Carlo;    free energy;    dielectric;    polarization;    like-charge attraction;    cluster algorithm;    rod;    tetrapod;    hypersphere;    quaternion;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/42215/Daniel_Sinkovits.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

I present research in the aggregation and self-assembly of charged macromolecules.This work aligns along three themes.The first theme is the effective interactions and aggregation of rodlike polyelectrolytes.The second theme is the self-assembly of colloidal tetrapods using Monte Carlo simulation.The third theme is the new techniques that needed to be devised in order to perform this work.Chapter 2 presents an extensive exploration of the free-energy landscapes governing the interaction between two rodlike polyelectrolytes with additional trivalent salt.Analysis reveals the relative stability of different aggregated configurations and the likely pathways taken toward first contact and subsequent rearrangement.Chapter 3 presents a study of the effect of including the low dielectric constant interior of rodlike polyelectrolytes has on their mutual interactions, paying particular attention to the many-body interactions, making connection to the stability of a hexagonal-packed bundle.I also explain the mechanism of interaction using ion distributions and pair correlation functions.Finally, I investigate quantitatively to what extent the effect of polarizability is simply to create an additional soft excluded-volume potential.In Chapter 4, I present study of the self-assembly of charge-functionalize colloidal tetrapods that have full mobility using Monte Carlo simulation.I find a change in the degree and structure of aggregation with increasing coupling.I also study the addition of positively or negatively charged nanoparticles, demonstrating a concentration-dependent change in the aggregate structure.Chapter 5 presents a new Monte Carlo simulation algorithm that was used to perform the work in Chapter 4.It is an extension of the geometric cluster algorithm that allows the simulation of anisotropic particles.I provide a detailed derivation of the algorithm, and I also include benchmark results and a study of the efficiency of the algorithm compared to Metropolis Monte Carlo.Chapter 6 explains the correct method for pressure calculation in systems that contain dielectric objects, as was the case for the periodic hexagonal array of polarizable polyelectrolytes simulated in Chapter 3.I also present a review of pressure calculation with periodic boundary conditions, since this is relevant to the dielectric calculation and there fundamental subtleties that are not treated in textbooks nor do concise reviews exist in the literature.