Preparation and Performance of Epoxy Resin Composite Microspheres with Controllable Wettability

In this study, a new type of raspberry epoxy resin composite particle had been proposed. First, a reaction-induced phase separation method was used to solidify epoxy resin in PPG1000 to prepare homogeneous macromolecular epoxy resin microspheres (EMs). Then, a sol–gel method was used to hydrolyze tetraethoxysilane (TEOS) to prepare nanoparticles of silicon dioxide. In alkaline conditions, the two microspheres were compounded by isocyanate-terminated polyurethane oligomers (PU) to prepare raspberry-shaped EP-PU@SiO₂ composite particles. By adjusting the content of PU, the wettability of the composite particles (110°~156°) can be controlled. The surface morphology of the composite particles was observed via scanning electron microscopy (SEM). The test results indicate that, under the circumstance of the same mass ratio of EMs/SiO₂, when the content of PU is relatively low, there is essentially no SiO₂ attached to the surface of EMs; when the content of PU is relatively high, a raspberry-like structure is observed. Furthermore, the influence of different EMs/SiO₂ mass ratios on the wettability of the composite microspheres was examined. Although the degree of infiltration may differ slightly, it is not significant. This indicates that PU is the decisive factor in controlling the wettability of the EP-PU@SiO₂ composite particles. When the PU content is 400% and the mass ratio of EMs to SiO₂ is 1 : 1, the static water contact angle of the EP-PU@SiO₂ composite microspheres attains the maximum value of 156.2°.