Influence of Molecular Packing and Confinement on the Glassy State Properties of Polymer Brushes

Polymer brushes consist of chains chemically attached to a substrate by one end. The distinctive morphology provides a means to independently control film thickness and molecular packing in a manner not feasible for spin-coated films. As a result, polymer brushes offer a unique opportunity for comparison with spin-coated films and irreversibly adsorbed layers. Indeed, initial investigations suggest that molecular packing has a strong impact on thin film properties, in particular the glass transition temperature. However, there has been less attention focused on the combined influence of molecular packing and confinement on physical aging of thin films. Here, we apply ellipsometry and fluorimetry to investigate the physical aging response of polymer brushes. Specifically, we will consider the impact of confinement on physical aging of polymer brushes by varying film thickness while keeping the grafting density constant. Additionally, we will consider the effects of molecular packing on physical aging by varying grafting density while keeping film thickness constant. Ultimately, this set of investigations will help to elucidate new ways to control thin film material properties.