Physics – Condensed Matter – Soft Condensed Matter
Scientific paper
2003-01-14
Eur. Phys. J. E, v.11, p.213 (2003)
Physics
Condensed Matter
Soft Condensed Matter
18 pages, submitted to Eur. Phys. J. E, expanded discussion section
Scientific paper
10.1140/epje/i2003-10015-9
We study irreversible polymer adsorption from dilute solutions theoretically. Universal features of the resultant non-equilibrium layers are predicted. Two cases are considered, distinguished by the value of the local monomer-surface sticking rate Q: chemisorption (very small Q) and physisorption (large Q). Early stages of layer formation entail single chain adsorption. While single chain physisorption times tau_ads are typically microsecs, for chemisorbing chains of N units we find experimentally accessible times tau_ads = Q^{-1} N^{3/5}, ranging from secs to hrs. We establish 3 chemisorption universality classes, determined by a critical contact exponent: zipping, accelerated zipping and homogeneous collapse. For dilute solutions, the mechanism is accelerated zipping: zipping propagates outwards from the first attachment, accelerated by occasional formation of large loops which nucleate further zipping. This leads to a transient distribution omega(s) \sim s^{-7/5} of loop lengths s up to a size s_max \approx (Q t)^{5/3} after time t. By tau_ads the entire chain is adsorbed. The outcome of the single chain adsorption episode is a monolayer of fully collapsed chains. Having only a few vacant sites to adsorb onto, late arriving chains form a diffuse outer layer. In a simple picture we find for both chemisorption and physisorption a final loop distribution Omega(s) \sim s^{-11/5} and density profile c(z) \sim z^{-4/3} whose forms are the same as for equilibrium layers. In contrast to equilibrium layers, however, the statistical properties of a given chain depend on its adsorption time; the outer layer contains many classes of chain, each characterized by different fraction of adsorbed monomers f. Consistent with strong physisorption experiments, we find the f values follow a distribution P(f) \sim f^{-4/5}.
O'Shaughnessy Ben
Vavylonis Dimitrios
No associations
LandOfFree
Irreversible Adsorption from Dilute Polymer Solutions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Irreversible Adsorption from Dilute Polymer Solutions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Irreversible Adsorption from Dilute Polymer Solutions will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-219779