Dimension-Dependent Mechanical and Thermophysical Properties of Antiplasticized Polymeric Nanostructures

Polymer dynamics and chain mobility are heavily influenced by the presence of interfaces, and in lithographically-defined polymeric structures of nanoscopic dimensions, interfaces play a governing role on the structures' mechanical and thermophysical properties. Near the free surfaces of polymeric nanostructures, chain mobility is enhanced relative to the bulk state, resulting in monotonic decreases in both the elastic modulus and glass transition temperature with decreasing nanostructure width.;Antiplasticizers are promising candidates for counteracting dimension-dependent mechanical properties. Antiplasticizers are nonvolatile additives that simultaneously increase the elastic modulus and decrease the glass transition temperature of bulk polymers when blended at low concentrations. On a nanoscopic level, antiplasticizers may have the added benefit of homogenizing the dynamics of polymer nanostructures throughout their width, mitigating the manifestation of dimension-dependent properties.;This dissertation highlights a specific polymer/antiplasticizer blend and provides an experimental characterization of the mechanical properties and glass transition of the blend at both macroscopic and nanoscopic length scales. In the bulk, these properties are characterized by dynamic mechanical analysis and differential scanning calorimetry. The effects of antiplasticization are quantified in both the glassy and rubbery regimes.;The mechanical properties of lithographically-defined antiplasticized nanostructures are quantified through observations of the collapse of the structures in the presence of well-defined capillary forces. Collapse data are coupled with an elastic cantilever beam bending model to estimate the elastic modulus of the structures. The elastic modulus determined through pattern collapse is dimension-dependent, and is increased by 20% or more through antiplasticization.;The properties of nanoimprinted polymer structures are quantified near the glass transition temperature through in-situ observations of pattern leveling by small angle X-ray scattering. The polymer nanostructures undergo a rapid shape evolution above a dimension-dependent critical temperature. Antiplasticized nanostructures exhibit a weakened dimension-dependence at the expense of decreased flow temperatures. In the limit of infinite line width, the critical flow temperature agrees with the bulk antiplasticizer concentration-dependent glass transition temperature.;This dissertation illustrates that the properties of bulk and nanoscopic polymeric structures can be easily tuned by antiplasticizing additives, enabling the production of polymeric nanostructures with robust and precisely tailored mechanical and thermophysical properties.