Mechanisms of Hydrophobic Recovery of Poly(dimethylsiloxane) Elastomers after Plasma/Corona Treatments: A Minireview

Plasma/corona treatment could alter the wettability of a poly(dimethylsiloxane) (PDMS) surface from being hydrophobic to being hydrophilic, which has attracted many researchers' attention. However, the treated surface will gradually recover its hydrophobicity as it ages. To understand the recovery, many studies have been performed. Although there is still no general consensus on the recovery mechanisms, several models have been proposed that can explain the reported wetting behavior of hydrophobic recovery. In this minireview, we summarized the reported mechanisms underlying the hydrophobicity-recovery of oxidized PDMS surfaces, which are certainly affected by varied factors including temperature, aging time, stored conditions, and treatment conditions. We hope this minireview can give beginners in the field of microfluidics a better understanding on the various mechanisms that contribute to the hydrophobic recovery of PDMS surfaces and thus take appropriate measures to efficiently maintain the surface wettability of oxidized PDMS chips to prolong their performance.