Neutron reflectometry yields distance-dependent structures of nanometric polymer brushes interacting across water. Issue 34 (2nd August 2017)

• Record Type: Journal Article
• Authors: Rodriguez-Loureiro, Ignacio; Scoppola, Ernesto; Bertinetti, Luca; Barbetta, Aurelio; Fragneto, Giovanna; Schneck, Emanuel
• Is Part Of: Soft matter. Volume 13:Issue 34(2017)
• Page Start: 5767
• Page End: 5777
• Publication Date: 2017-08-02
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c7sm01066d
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : The conformation of interacting polymer brushes is of biological and technological importance as it affects interaction forces and shear friction. Abstract : The interaction between surfaces displaying end-grafted hydrophilic polymer brushes plays important roles in biology and in many wet-technological applications. In this context, the conformation of the brushes upon their mutual approach is crucial, because it affects interaction forces and the brushes' shear-tribological properties. While this aspect has been addressed by theory, experimental data on polymer conformations under confinement are difficult to obtain. Here, we study interacting planar brushes of hydrophilic polymers with defined length and grafting density. Via ellipsometry and neutron reflectometry we obtain pressure–distance curves and determine distance-dependent polymer conformations in terms of brush compression and reciprocative interpenetration. While the pressure–distance curves are satisfactorily described by the Alexander-de-Gennes model, the pronounced brush interpenetration as seen by neutron reflectometry motivates detailed simulation-based studies capable of treating brush interpenetration on a quantitative level.