Facile Synthesis of Free-Standing Polymer Brush Films Based on a Colorless Polydopamine Thin Layer

A free-standing polymer brush film with tailored thicknesses based on a colorless polydopamine (PDA) thin layer is prepared and characterized. The surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) is performed on a PDA layer with thickness of ca. 6 nm, which generated an optically transparent and colorless free-standing PHEMA brush film (1.5 cm x 1.5 cm). Because the cross-linked PDA layer is used as the base for the polymer brushes, the reported method does not require cross-linking the polymer brushes. The free-standing film thicknesses of approximate to 16-75 nm are controlled by simply changing the ATRP reaction time. The results show that the free-standing PHEMA brush film transferred onto a plate exhibits a relatively smooth surface and is stable in any solvent.