Molecular Dynamics Study of Hydrated Poly(ethylene oxide) Chains Grafted on Siloxane Surface
In this work, hydrated poly(ethylene oxide) (PEO)chainscomposedofvaryinglengthNirreversiblygrafted to an amorphous siloxane surface by one chain end at different coverage densities σ were studied using atomistic molecular dynamics simulations. We have assessed beginning of the ex- tended overlapping chains (brush regime) at σ= 0.437 nm � 2 and identified the mushroom-like conformation of nonoverlapping chains. For the studied systems, the specific interactions lead to density distributions different from the functions analytically derived for model systems. The brush regime demonstrates itself in the density distribution functions and the reduced height h/N evolution with σ. Since the latter dependence indicates h ∼ Nσ 1/2 scaling, the brush regime corresponds to the situation of a concentrated aqueous PEO solution with a correlation length σ � 1/2 . The extrapolated thickness of PEO brushes reproduces experimental results fairly well. Water molecules prevent EO monomers from an adsorption to the siloxane surface.