chapter  2
Friction of Polyethylene-b-Poly(ethylene glycol) Diblock Copolymers against Model Substrates
Pages 19

The objective of this study was to investigate the friction properties of polyethylene-b-poly(ethylene glycol) diblock copolymers (PE-b-PEG) against model substrates. Several PE-b-PEG copolymers containing different PE/PEG ratios were studied. Two model substrates used were a hydrophilic glass plate and a hydrophobic glass plate (obtained by methyl-terminated silane grafting). The influences of both the PE-b-PEG copolymer composition and the nature of the substrate on the friction properties are discussed. Experimental results show a decrease in the friction coefficient against the hydrophilic substrate when the PEG content is increased. This result is explained by the amorphous state of the PEG blocks, whose mobility allows adsorption on the hydrophilic surface. For copolymers containing a low PEG content, a higher friction coefficient is obtained for the hydrophilic glass, compared with the hydrophobic substrate. However, for copolymers containing a high PEG content, a higher friction coefficient is measured for the hydrophobic glass compared with the hydrophilic glass. The crystalline and amorphous states of each block are therefore able to influence the tribological behavior of these copolymers.