Embodiments herein relate to window spacer assemblies including surfaces with relatively high surface energy. In an embodiment, a window spacer assembly is included. The window spacer assembly including a spacer body having an inner surface, an outer surface, and lateral surfaces. The window spacer assembly further includes a first sealant disposed on the lateral surfaces. Portions of the window spacer assembly such as an outer surface or lateral surface of the spacer body and/or a moisture vapor barrier layer disposed over the outer surface can be treated to have a higher surface energy. Other embodiments are also included herein.