MOLECULAR DYNAMICS INVESTIGATION OF HEAT TRANSFER IN SOLVATED PLASMONIC NANOPARTICLES
Restricted (Penn State Only)
- Author:
- Paniagua Guerra, Luis
- Graduate Program:
- Mechanical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- October 04, 2023
- Committee Members:
- Bladimir Ramos Alvarado, Chair & Dissertation Advisor
Adri van Duin, Major Field Member
Robert Kunz, Professor in Charge/Director of Graduate Studies
Daniel Hayes, Outside Unit & Field Member
Linxiao Zhu, Major Field Member - Keywords:
- Molecular Dynamics
Nanoscale Heat Transfer
Gold Nanoparticles
Self-Assembled Monolayers
Solid-Liquid Interfaces - Abstract:
- The objective of this thesis is to investigate the underlying mechanisms of thermal transport across gold-water interfaces with an emphasis on characterizing heat transfer in solvated plasmonic nanoparticles. Molecular dynamics simulations were used to investigate interfacial heat transfer in solvated nanoparticles. Therefore, the first part of the present investigation assesses a variety of force field parameters available in the literature to model heat transfer across gold-water interfaces. A description of the local pairwise interaction energy was used to describe the solid-liquid affinity of flat and curved surfaces. Partly conclusive trends were observed between the total pairwise interaction energy and the thermal boundary conductance. It was observed that the solid surface structure, interfacial force field type, and force field parameters created a characteristic bias in the interfacial water molecules (liquid structuring). Consequently, a study of the liquid depletion layer and computation of the density depletion length, which describes the deficit or surplus of energy carries (water molecules) near the interface, resulted in a better description of interfacial thermal transport. It was observed that interfacial heat transfer is favored when the water molecules organize in cluster-like structures near the interface, by a surplus of water molecules at the interface, i.e., lower density depletion length, and by the closeness of water to the solid atoms. The second part of this investigation deals with thermal transport across gold-water interfaces grafted with self-assembled monolayers (SAMs). Among the thiolates on the SAMs under study, 2-furanmetanethiolate, 2-thienylmetanethiolate, and pirrole-2-carboxylic acid + cysteamine were selected due to their applicability in drug delivery systems based on click chemistry. Therefore, with a focus on drug release systems based on retro-Diels-Alder reactions, thermal transport is also investigated at gold-water interfaces functionalized by thiolates bonded to a maleimide compound. It was found that although thermal transport is enhanced by the functionalization of the gold surface, the thermal boundary conductance enhancement is compromised by the inclusion of the maleimide compound. A tradeoff of interfacial mechanisms was found behind the thermal transport behavior of the functionalized gold-water interfaces, highlighting the penetration of water molecules on the SAM and the efficient vibrational coupling between the thiolates in the SAM and the interfacial water molecules. Nevertheless, the trends found in the bare Au-water interfaces with the density depletion length were absent from functionalized interfaces, pointing to the complexity of gold-SAM-water interfaces.