Onset of Tethered Chain Overcrowding

Tethered polymer chains on substrates have been recognized to be an important topic in enabling a wide range of surface applications associated with bioand nano-technologies. However, a fundamental understanding of these systems has been restricted by experimental difficulties. Our group proposed a new method to use lamellar single crystals of two series of diblock copolymers, poly(ethylene oxide)block-polystyrene (PEO-b-PS) and poly(Llactic acid)-block-polystyrene (PLLA-b-PS), grown in different dilute solutions as templates to generate tethered polystyrene chains on the crystalline substrates. By monitoring the thickness changes of the single crystal as a probe, the onset of tethered chain overcrowding has been found to be a sharp transition, which happens universally at a reduced tethering density value of 3.7-3.8 for these systems.