Nanotribological behavior of tethered reinforced polymer nanolayer coatings

We fabricated molecularly thick thermoplastic elastomeric films with organi zed microdomain structure and intriguing nanotribological properties. Molec ular films from poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) wer e obtained by a melt/solution grafting to a functionalized silicon surface modified with epoxy-terminated self-assembling monolayers. We varied the th ickness of grafted block-polymer films from 1.35 nm (disordered polymer lay er) to 9 nm (well defined nanophase structure) and tested their friction, a dhesion, shear and wearing properties on a microscale with scanning probe m icroscopy. Tethered SEBS monolayers, composed of a rubber matrix reinforced by a two-dimensional net of glassy polystyrene (PS) microdomains, possess a friction coefficient as low as 0.02 and shear strength in the range 0.15- 1.5 Gpa. Chemically tethered SEBS monomolecular films are much more stable under shear stresses than conventional molecular coatings. (C) 2001 Elsevie r Science Ltd. All rights reserved.