Numéro
J. Phys. France
Volume 51, Numéro 8, avril 1990
Page(s) 701 - 707
DOI https://doi.org/10.1051/jphys:01990005108070100
J. Phys. France 51, 701-707 (1990)
DOI: 10.1051/jphys:01990005108070100

Forces between asymmetric polymer brushes

D.F.K. Shim et M. E. Cates

Theory of Condensed Matter, Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE, G.B.


Abstract
We study the equilibrium compression of asymmetric polymer brushes grafted on flat plates, under athermal and theta solvent conditions, using a lattice self-consistent field (SCF) approach. We find that the separation d between two plates coated asymmetrically with brushes of type 1 and 2, as a function of the force F, obeys the "bisection rule", d(F) = (d1(F) + d 2(F)) /2 where d1(F)and d 2(F) are the corresponding separations for the symmetric brushes of type 1 and 2 respectively.The bisection rule is easily esplained if one assumes no interpenetration of the two brushes. However, a study of the polymer volume fraction profiles suggests that the bisection rule is well obeyed even when there is strong interpenetration. The relevance of this work to recent experiments on asymmetric brushes is discussed.

PACS
6843 - Chemisorption/physisorption: adsorbates on surfaces.
3420 - Interatomic and intermolecular potentials and forces, potential energy surfaces for collisions.
3620E - Conformation (statistics and dynamics).
6141 - Polymers, elastomers, and plastics.

Key words
adsorbed layers -- intermolecular mechanics -- macromolecular dynamics -- polymer blends -- polymer films -- SCF calculations -- solvent effects