Liquid nano-patterning between apposing brushes under pressure

KIM, YONGWOOK; CLAUDIO PASTORINO; MARCUS MÜLLER; MINKO, SERGIY

Buenos Aires

Conferencia; Stat Phys 27; 2019

IUPAP

We demonstrate that, upon compression, a poor solvent between two apposingpolymer brushes does not remain a uniform thin film but, instead, formslateral, nanoscopic structures. This is shown by computer simulations of acoarse-grain polymer model and scaning probe microscopy experiments of PolytBAbrushes in Ethanol. The characteristic lateral length scale of the solventdomains scales with the brush height that, in turn, can be controlled by thegrafting density, molecular weight or pressure. These findings are rationalizedin terms of geometric considerations, accounting for the interfacial freeenergy between the solvent and the brush and the spatial arrangement of thegrafted chains. This phenomenon offers a general strategy to laterallystructure confined fluids.In addition, we study liquid flow in a brush-coatedcylindrical nanochannel in the same physical limit, in which chains from oppositesides of the channel can interact among them. We find droplets as theequivalence of liquid nanostructures in the plannar geometry, andvery interesting flow properties.