Molecular assemblies are promising candidates for nano-scale electronics due to their chemical and structural versatility. The successful fabrication of assembly-based nano-scale electronics, where molecular assemblies comprise the electrically-active components, requires the ability to reliably form molecular assemblies and the ability to 'wire them into electrical junctions. This dissertation focuses on the processing-structure relationships of model conjugated dithiols, the formation of electrical junctions with these molecular assemblies, and the characterization of these junctions. Biphenyldithiol (BPDT), terphenyldithiol (TPDT), and quaterphenyldithiol (QPDT) are assembled in solution from their thioacetyl precursors which are converted in-situ to thiolates using NH4OH. We elucidated how the type of substrate, the solvent quality, and the concentrations of NH4OH and the thioacetyl precursors affect the final structures of these assemblies. BPDT molecular assemblies are disordered on both gold (Au) and gallium arsenide (GaAs) at all conditions explored. TPDT and QPDT adopt the most upright molecular orientations on both Au and GaAs when the assembly is carried out from EtOH-rich solutions at low NH4OH and high precursor concentrations. At these conditions, the assembly formation process is dominated by the adsorption of thioacetylterminated molecules. When the assembly is carried with high NH4OH and low precursor concentrations, adsorption is dominated by thiolates; TPDT and QPDT are disordered on Au and GaAs. None of the molecules adsorb significantly on GaAs from THF. The presence of S-Au bonds at the molecular assembly -- top Au contact interface was directly probed by x-ray photoelectron spectroscopy. Depositing Au electrodes on QPDT assemblies by nTP in dichloroethane results in the reproducible formation of S-Au bonds at the molecule-Au interface. Finally, we measured the electrical response of the model conjugated molecular assemblies on GaAs through direct contact with galinstan. The current densities scale inversely with the tunneling distance, which is determined by factors including the length of the conjugated molecule and the molecular orientation of the assembly. We also examined the electrical response of GaAs--QPDT--Au junctions in which the Au electrodes were transferred using an elastomeric stamps. The electrical characteristics of these junctions were independent of orientation of the molecules and the presence of SAu bonds at the charge transfer nterface. Hydrocarbon contamination on the Au electrodes left by the elastomeric stamp during transfer masked any electrical response from QPDT. It is therefore crucial to ensure the pristine quality of the electrical contact in order to reliably measure the electrical response of the molecular assembly. The fabrication and testing of assembly-based electrical junctions is challenging in terms of both controlling the assembly structures and measuring their electrical response. Careful attention must therefore be paid to each aspect of molecular assemblybased junction formation and characterization. / text

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Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Neal Zondlo, Dept. of Chemistry & Biochemistry. Includes bibliographical references.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: Michael A. Brook. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2009. / Title from PDF title page (University of Texas Digital Repository, viewed on Aug. 12, 2009). Vita. Includes bibliographical references (leaves 99-105).

Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2006. / Bredas, Jean-Luc, Committee Member ; Sherrill, C. David, Committee Chair ; Hernandez, Rigoberto, Committee Member.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 179-191).

The blending or mixing is extensively utilized in diverse processes of polymers to bring about advantageous properties, but the behavior becomes intriguing when associations are involved and multi-solvents are used. Explanations based on chemistry-specific arguments are less than satisfactory in abstracting essential features, and lack the general applicability across various systems. So, this work focuses on capturing the physical force governing the phenomenon of interest by using a generic model. Highly non-trivial behaviors of polymers are often observed in multi-solvent solutions. It is known that polymers swell and dissolve in good solvents, while they tend to collapse and aggregate in poor solvents. But for some specific systems, polymers that collapse in two different poor solvents become soluble in their mixtures, corresponding to cosolvency, and conversely, polymers that swell in two different good solvents become insoluble in their mixtures, pertaining to cononsolvency. The finding suggests that cononsolvency effect relies on the interplay between polymer-cosolvent preferential adsorptions and solvent-cosolvent attractions, which are typically investigated individually. The utilization of cononsolvency effect can either modify or induce micellization, leading to significant differences in morphology and thermodynamic properties compared to conventional micelles driven solely by hydrophobic interactions. The cosolvency project reveals that it arises from the cross competitions of Van der Waals-type interactions and the associative interaction (e.g., hydrogen bonding). The molecular association has long been a classical problem in physical chemistry, as it often gives rise to ”abnormal” phenomena, such as the elevation of boiling points due to hydrogen bonding. But the understanding of its effect on polymer system still remains rudimentary. So, this work tries to answer three fundamental questions by choosing three representative systems: 1. How will supramolecular complexations change the thermodynamics equilibrium morphology; 2. What is the impact of supramolecular bonds on the free energy landscape during the transition process; 3. How will association influence the single chain coil-globule conformational transition. It is found that the association not only results in versatile morphology, but also brings about distinct transition pathways. Besides, the conformational transition shows the dependence on the association pattern, which is actually decided by the statistical nature.