Neutron reflectometry study for structure control of a phenolic resin–silica interface

Abstract

To control the interfacial structure of hexamethylenetetramine (HMTA)-cured phenolic resins on the silica surface, neutron reflectometry analysis was performed by varying the HMTA concentration, the molecular weight distribution of novolac resins, and the wettability of the silica surface. The thickness of the interface layer observed as a novolac adsorption layer was not affected by the HMTA concentration or the novolac molecular weight distribution, while it became thicker as the silica surface more hydrophobic. The roughness of the interface layer decreased as the polydispersity of the novolac resins became narrower, giving the flat interface structure, while the roughness increased as the silica surface wettability became more hydrophobic, resulting in the formation of interface structure on the silica surface with an unclear boundary to the bulk resin layer.