Observation of Three Growth Mechanisms in Self-Assembled Monolayers

Abstract

Time-resolved atomic force microscopy and contact angle measurements reveal that the self-assembly of octadecyltrichlorosilane-based monolayers on the oxidized Si(100) surface can be initiated by three distinct mechanisms: island growth at low temperatures (T < 16 °C), homogeneous growth at high temperatures (T g 40 °C), and a mixed regime at intermediate temperatures. These results support the notion of a transient Langmuir film at the substrate-solution interface: the observed growth patterns are consistent with nucleation of liquid-condensed domains coexisting with a two-dimensional gas at low temperature, or with a liquidexpanded phase at intermediate temperatures.

Use of Self-assembled Monolayers at Variable Coverage to Control Interface Bonding in a Model Study of Interfacial Fracture: Pure Shear Loading

“…Previous reports have indicated island formation under certain conditions of temperature and chain length due to a lateral phase transition [17][18][19]. We prepared substrates with ODTS deposited both by island growth and homogeneous growth to determine whether this difference has any effect on the .…”

“…The smooth surfaces also allowed extensive characterization of the SAM prior to applying the epoxy and also after fracture. SAM chemistry using trichlorosilane end groups on silicon oxide is well established [16][17][18][19]. By varying the deposition temperature, the deposition can occur by either island growth or single chain growth.…”

Molecular-To-Continuum Fracture Analysis of Thermosetting Polymer/Solid Interfaces

“…AFM was used to examine the degree of lateral heterogeneity within the incomplete monolayer. Previous reports have indicated island formation can occur under certain conditions of temperature and chain length due to a lateral phase transition (Carraro et al, 1998, Huang, et al, 1997, Bierbaurn, et al, 1995, Banga, et al, 1995. Our concern was to detemine the conditions for which island formation occurred in our samples, and whether island formation has any effect on the fracture behavior.…”

Aqueous silane-surfactant co-dispersions for deposition of hydrophobic coatings onto pre-oxidized polysilicon

“…Depending on reaction conditions, the formation of complete monolayers with a dense organized assembly with aligned hydrocarbon chains or the creation of a coating with disordered molecules that have not self-assembled to form condensed domains can be observed. The relative proportion of ordered and disordered phases depends on water concentration [5,6], solution age, chain length of silane molecules, temperature [7][8][9], silane concentration, exposure or reaction time, dispersion pH [10], substrate pre-treatment [11] and steric effects [12,13]. While incomplete monolayers are formed in the absence of water, excess water results in the hydrolysis and condensation of trifunctional silanes in the bulk liquid-phase as well as at the solution/solid interface.…”