Using covalent and non-covalent chemistry to control properties of single-walled carbon nanotubes.

摘要

Single-walled carbon nanotubes (SWNT) exhibit exceptional electronic, mechanical, and optical properties, making them the subject of intense study. The functionalization of SWNT via covalent or non-covalent strategies has been widely utilized to increase solubility in aqueous or organic solvents, and facilitate the assembly of carbon nanotubes onto surfaces. Control of the moiety bound to the SWNT surface allows the control of SWNT properties and the realization of many applications. However, to date, few studies have focused on quantitatively linking the effect of functionalization to key SWNT properties with existing theory. This work demonstrates the control of SWNT properties using covalent and non-covalent functionalization and quantifies the effect using accepted theoretical models. SWNT properties under examination include: electrophoretic mobility, solution-phase solubility, and surface adsorption thermodynamics.;Electrophoretic mobility control is demonstrated via covalent functionalization with 4-hydroxybenzene diazonium and non-covalent functionalization with sodium cholate surfactant. Solution-phase solubility without surfactants can be achieved using high levels of covalent functionalization with aryl hydroxyl or aryl carboxylic acid moieties. Polymer theory based models for the Hildebrand and Hansen solubility parameters confirm the effect of functionalization. The adsorption of SWNT to silicon oxide surfaces modified with 3-aminopropyltriethoxysilane (APTES) is controlled via type of functional moiety, extent of functionalization, and nature of silicon oxide surface chemistry. Self-consistent field theory for polymer systems is applied and describes the effect of functionalization on SWNT adsorption thermodynamics.