Surfactant Release from Hydrophilized Vinylpolysiloxanes

Abstract

Vinylpolysiloxane impression materials (VPS) exhibit an apolar (hydrophobic) backbone chemistry. Hence, surfactants are added to improve their hydrophilicity for impression-taking in moist environments. However, the mechanisms at the liquid-VPS-interface regarding the surfactant are unknown. We hypothesized that surfactant is leached from the VPS. Four experimental VPS formulations were fabricated containing 0 (control), 1.5, 3, and 5 wt% non-ionic surfactant. Samples were prepared (n = 6) and contact angles determined 30 min after mixing. After 60 sec, droplets were transferred onto the control. Mass spectrometry was used to analyze the droplets. Contact angles were inversely correlated with the surfactant concentration (p < 0.05). Droplets transferred from hydrophilized specimens onto the control showed similar contact angles. Surfactant could be clearly identified inside the droplets from the hydrophilized samples, however, not inside the control. Surfactants reduced the surface tension of the liquid in contact and did not change the surface properties of the VPS itself.