Atomic force microscopy and scanning electron microscopy characterization of the controlling of surface morphology of epoxy-amine-cured spin-coated films

Atomic force microscopy (AFM) was successfully used to study spin-coated, amine-cured epoxy film microstructure and morphology. The air-epoxy and epoxy-substrate interfaces were examined using tapping-mode height and phase imaging AFM. The impact of relative humidity on the morphology and microstructure of the surfaces was determined. AFM was able to elucidate the changes on the surface as relative humidity during processing increased. It was observed that large nodular formations formed on the epoxy surface expose to the air but not epoxy surface formed on the substrate in addition to varying regions of more or less compliant structures, which was attributed to carbamate formation caused by the amine curing agent reaction with atmospheric CO2. Scanning electron microscopy (SEM) was used to further elucidate interface and interphase morphology of spin-coated epoxies. Experimentation also demonstrated that post-curing above the glass transition did not change the morphology structure, suggesting surface structures are "locked-in." SEM was used to further elucidate how the interface and interphase change with changing environmental conditions at both the air-epoxy and epoxy-substrate interface/interphases, including the impact of atmospheric CO2 on Marangoni cell formation. Controlling spin coated surface morphology through environmental conditioning.image