Preparation and surface properties of polydimethysiloxane/polycaprolactone/epoxy resin composites

Silyl-terminated polycaprolactone/ polydimethysiloxane (PCL-TESi/PDMS-TESi) was directly synthesized via —OH and —NCO nucleophilic addition reaction. A series of resin composites were prepared by blending epoxy and PCL-TESi/PDMS-TESi. The morphologies and the surface elements of the composite system were investigated by scanning electron microscopy and X-ray photoelectron spectroscopy. The surface tension of the composite system was obtained based on the contact angle by Owens-Wendt-Kaelble model. The water-resistance properties of the composites were also studied. The results show that the morphologies，surface tension and water resistance properties of the composites are quite dependent on the content of PCL-TESi/PDMS-TESi and the curing temperature. The surface tension decreases with increasing PCL-TESi/PDMS-TESi content because of the Si element migrating toward the surface to some extent. The compatibility of the two phases at 50℃ curing systems is better than that at room temperature curing systems，which results in that the composites cured at 50℃have higher surface tensions than those cured at room temperature. When the mass ratio of PCL-TESi/PDMS-ESi to the epoxy is 5∶5，the mass change of composite cured at room temperature is below 1% af ter soak in distilled water at 50℃ for 7 days.