Polymer brushes and polyelectrolyte multilayers are used in many applications where there is a need to tailor the interfacial properties and to promote a certain interaction with the surrounding environment. Layer conformation and the degree of hydration are key parameters influencing the interfacial properties. Here we present how layer build-up, conformational changes and molecular interaction with the polymer layer can be analyzed using QSense QCM-D technology.
Analyze layer build-up, interaction, and structural change
QCM-D is a surface sensitive technology which has been used to analyze polymer-based systems for almost two decades. Via time-resolved information on mass, thickness and viscoelastic properties of surface adhering layers, the method can monitor polymer layer build-up as well as molecular interaction with the polymer layers. QCM-D senses hydrated mass, i.e. the mass of both the polymer molecules and the coupled solvent. This makes it particularly suitable to for the analysis of dynamic behavior such the transition between hydrated and dehydrated states, i.e. water uptake and release, which are sensed as changes in mass , as illustrated in Fig. 1.
Figure 1. Top panel: Schematic illustration of A) polymer grafting to a surface followed by B) conformational change due to changes in external conditions, C) which is reversible when the conditions are changed back to the original setting. Middle panel: The layer grafting and conformational changes are characterized by QSense QCM-D, where Δf (blue) corresponds to mass changes at the surface and ΔD (red) corresponds to layer softness. Bottom: The quantified mass as a function of time.
Vary molecular and ambient conditions
Running QCM-D analysis at relevant conditions, varying for example surface (substrate) material, temperature, pH, salt concentration or salt type, the properties and dynamic behavior of the polymer-based system can be characterized as well as tailored for the target application.
Polymer layer properties and dynamic behavior that can be analyzed includes:
Grafting kinetics of polymer chains
Build-up of PEM:s
Conformational changes of polymer layers
Molecular interaction with polymer layers
Download the overview to read more about how polymer-based systems can be characterized using QSense QCM-D technology.
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