Two-Dimensional Melts:  Polymer Chains at the Air−Water Interface

Abstract

Both physical surface rheology and computer simulation experiments were performed to understand the conformation of polymers in 2D systems. The interfacial stress rheometer was used to measure surface rheological properties of Langmuir monolayers of poly(tert-butyl methacrylate) with molecular weights between 81.5 and 780 kg mol-1. The Π−A isotherms for these monolayers show two transitions: a plateau at Π ≈ 18 mN m-1 and a bend at Π ≈ 52 mN m-1. The properties of the films are shown to be substantially different above and below the plateau surface pressure, Πp. Below Πp, the monolayers are primarily viscous, and surface viscosity increases linearly with MW, while above Πp, the films are more elastic, and surface viscosity is MW-independent. Computer simulations of these systems produce qualitatively similar Π−A isotherms. The observed transition at Πp marks the changeover from polymer chains existing in a single layer to forming regions of multilayers.

Fourier-transform rheology of polymer Langmuir monolayers: Analysis of the non-linear and plastic behaviors

“…9), becoming near-reversible at the compressed state u ∼ u 0 . In any case, it must be considered that the above qualitative explanation may not be unique [32,38], and that the present data do not constitute a rigorous proof of it.…”

Rheology of poly(methyl methacrylate) Langmuir monolayers: Percolation transition to a soft glasslike system

“…Electronic mail: rgrubio@quim.ucm.es. Similarly, Gavranovic et al, 15 have reported the behavior of dilational viscosity for different polymers, and found that for dilute monolayers the viscosity did not depend on M w , while for more concentrated monolayers there was a linear dependence. In effect, the exponents of the power laws assumed for describing the composition dependence of elasticity and viscosity rely on the following dependence of the relaxation time upon the chain length (N): τ ∼ N 3 .…”

Scanning Force Microscopy as Applied to Conformational Studies in Macromolecular Research

“…[158] Among the obtained values there were some, which fell within the range of 0.77-0.79. These values were assigned to polymer chains with statistics of two-dimensional SAW and corresponding critical scaling exponent n ¼ 3/4.…”