Energy of adhesion of polydimethylsiloxane networks / glass and polycarbonate assemblies

Abstract

The reversible energy of adhesion of polydimethylsiloxane (PDMS) networks/substrate assemblies evaluated from surface energy values obtained by wettability measurements is compared with that determined by Johnson, Kendall and Roberts' (JKR) approach. The role of the hydroxyl groups of the PDMS chains in the establishment of the interactions with the glass substrate is confirmed. Indeed, by using the hydrosilylation reaction between vinyl functional groups on PDMS chains on the one hand and silyl hydride functional groups carried by other PDMS chains on the other, polymer networks are obtained without any by-products. Moreover, no hydroxyl groups are present in the polymer network and only interactions of the van der Waals type should occur between the polymer and the glass substrate, even in the presence of ammonia vapor, which has a catalytic effect on the formation of the polymer-substrate interactions involving the hydroxyl groups, as already shown. The JKR approach indicates that the interactions are stronger with the glass substrate than with the polycarbonate substrate, although the calculated reversible energy of adhesion is of the same order of magnitude. This result is expected, considering the characteristics of the glass surface, especially its acid-base character compared with that of the polycarbonate.