Interchain Monomer Contact Probability in Two-Dimensional Polymer Solutions

N Schulmann and H Meyer and JP Wittmer and A Johner and J Baschnagel, MACROMOLECULES, 45, 1646-1651 (2012).

DOI: 10.1021/ma300085a

Using molecular dynamics simulations of a standard bead-spring model, we investigate the density crossover scaling of strictly two-dimensional (d = 2) self-avoiding polymer chains without chain crossings focusing on properties related to the contact exponent theta(2) set by the intrachain subchain size distribution. With R similar to N' being the size of chains of length N, thet number n(int) of interchain monomer contacts per monomer is found to scale as n(int) similar to 1/N'(theta 2) with nu = 3/4 and theta(2) = 19/12 for dilute solutions and nu = 1/d and theta(2) = 3/4 for N >> g(p) approximate to 1/rho(2). Irrespective of the density rho, sufficiently long chains are thus found to consist of compact packings of blobs of fractal perimeter dimension d(p) = d - theta(2) = 5/4. In agreement with the generalized. Porod scattering of compact objects with fractal contour, the Kratky representation of the intramolecular form factor F(q) reveals a strong nonmonotonous behavior approaching with increasing density a limiting power-law slope F(q)q(d)/rho approximate to 1/(qR)(theta 2) in the intermediate regime of the wave vector q. The demonstrated intermolecular contact probability is argued to imply an enhanced compatibility of polymer blends.

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