Adhesive–adherent interfaces probed with grazing-incidence small-angle neutron scattering

Abstract

The inner structure of a pressure‐sensitive adhesive (PSA) is investigated at the surface as well as at the buried adhesive–adherent interface. Time‐of‐flight grazing‐incidence small‐angle neutron scattering (TOF‐GISANS) is used to obtain depth‐resolved structural information about the statistical copolymer poly(ethylhexylacrylate‐stat‐d‐methylmethacrylate), which represents a well studied model PSA comprising 80% ethylhexylacrylate and 20% deuterated methylmethacrylate. Small and rare defects of around 40 nm in lateral size are found at the surface, while in the probed film volume a very low concentration of smaller structures of between 25 and 37 nm is found. Acidic and basic cleaning procedures are applied to the silicon adherent to alter the surface chemistry. At the buried interface of the adhesive and adherent no lateral structures are resolvable, irrespective of the surface treatment. The absence of dominant lateral structures shows that the statistical copolymer does not phase separate on a length scale that is of interest for applications. Furthermore, the findings prove the suitability of this kind of sample system for reflectivity measurements and demonstrate the suitability of TOF‐GISANS for nondestructive investigations of buried interfaces in adhesion science.

Lyotropic Liquid Crystal (LLC)-Templated Nanofiltration Membranes by Precisely Administering LLC/Substrate Interfacial Structure

“…The scattering depth is another essential point for GISAS, which is given by [ 32 , 33 , 199 ]: where the l i and l f depend on the incident angle and exit angle of the beam, and absorption and critical angle of the medium.…”

“…The S(q) yields information on object positions, such as the interparticle distance, while the P(q) provides information about the shape and size of the objects [195,196]. The scattering depth is another essential point for GISAS, which is given by [32,33,199]:…”

“…X-ray and neutron techniques are more promising in non-destructively observing the buried LLC/substrate interfacial structures. The grazing incidence mode scattering technique is the most direct tool to identify the LLC phase structure at the interface by choosing a suitable beam incident angle [ 32 ], while neutron enables localization of the monomer molecules at the interface by contrast matching the deuterated amphiphile molecules and the mixtures of deuterated and hydrogen solvents [ 33 ].…”

Using Grazing-Incidence Small-Angle Neutron Scattering to Study the Orientation of Block Copolymer Morphologies in Thin Films

“…Neutrons are also uniquely sensitive to hydrogen and its isotope, deuterium. , With suitable instrumentation, GISANS has been increasingly used over the past three decades . Müler-Buschbaum pioneered the earliest studies on thin films by GISANS in an extensive series of studies on polymer thin films about surface roughness, interdiffusion of polymers, single-chain conformations, , dewetting of homopolymers and copolymers, − hydration of micelles, adhesive-adherent interfaces, and composite materials for photovoltaic, − magnetic, , and Li-ion battery applications. , Felcher and Adenwalla investigated Zeeman splitting when polarized neutrons impinged on a ferromagnetic surface at a grazing angle . GISANS has since been widely used to study micelles − and other nanomaterials near surfaces and interfaces .…”