Characterization of polymer brushes in capillaries

The synthesis of various polymer brush coatings were performed in 0.075 mm i.d. fused silica capillary tubing by atom transfer radical polymerization (ATRP). Although characterization of polymer coatings inside of capillaries is extremely difficult, we will show how fluorescence spectroscopy can be used as a technique to verify that covalently attached polymer brushes are present. Capillary rise measurements show the Zisman critical surface energy (γc) changes as the polymer coatings are changed from either hydrophilic or hydrophobic. The hydrophilic and hydrophobic nature of polymers leads to selective flow behavior in micro-capillaries that will allow passive flow control.