Sat, 26 Jul 2008 04:18:03 BST CiteULike: Author Johner http://www.citeulike.org/author/Johner CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/6rheology/article/2870707 <i>Macromolecules, Vol. 29, No. 6. (11 March 1996), pp. 2179-2196.</i><br /><br />Abstract: We present a theoretical description of polymer adsorption from solution which is based on a mean field approximation but which goes beyond the standard ground state dominance approximation. The properties of the adsorbed polymer chains are described by two coupled order parameters. This allows a description of the chains in terms of tails and loops. When the bulk solution is dilute, the adsorbed polymer layer has a double layer structure with an inner layer dominated by loops and an outer layer dominated by tails. Explicit asymptotic forms are found for the monomer concentration profile and for the crossover distance between the loops and tail regions. The precise concentration profile is obtained by a numerical solution of two coupled differential equations. One of the surprising results is that the total polymer adsorbed amount has a nonmonotonic variation with molecular weight and decreases for large values of the molecular weight. The concentration profiles are also determined when the bulk solution is semidilute or concentrated. At any bulk concentration, the monomer concentration has a nonmonotonic variation with the distance to the adsorbing wall and shows a minimum at a finite distance. This depletion effect can be significant in the vicinity of the crossover between dilute and semidilute solutions. All the results are in agreement with the existing numerical solutions of the complete mean field theory of polymer adsorption. Excluded volume correlations are taken into account by constructing scaling laws for polymers in a good solvent both in dilute and in semidilute solutions. Adsorption of Polymer Solutions onto a Flat Surface AN Semenov J Bonet-Avalos A Johner JF Joanny doi:10.1021/ma950712n Macromolecules, Vol. 29, No. 6. (11 March 1996), pp. 2179-2196. 2008-06-07T06:13:16-00:00 1996 Macromolecules 29 6 2179 2196 coating lab3 http://www.citeulike.org/user/dchen/article/2767637 <i>Physical Review Letters, Vol. 100, No. 10. (2008)</i><br /><br />We introduce a general methodology based on magnetic colloids to study the recognition kinetics of tethered biomolecules. Access to the full kinetics of the reaction is provided by an explicit measure of the time evolution of the reactant densities. Binding between a single ligand and its complementary receptor is here limited by the colloidal rotational diffusion. It occurs within a binding distance that can be extracted by a reaction-diffusion theory that properly accounts for the rotational Brownian dynamics. Our reaction geometry allows us to probe a large diversity of bioadhesive molecules and tethers, thus providing a quantitative guidance for designing more efficient reactive biomimetic surfaces, as required for diagnostic, therapeutic, and tissue engineering techniques. Measuring the Kinetics of Biomolecular Recognition with Magnetic Colloids Cohen Tannoudji E Bertrand J Baudry C Robic C Goubault M Pellissier A Johner F Thalmann Lee CM Marques J Bibette doi:10.1103/PhysRevLett.100.108301 Physical Review Letters, Vol. 100, No. 10. (2008) 2008-05-07T23:01:32-00:00 2008 Physical Review Letters 100 10 APS 2008 colloids magnetic http://www.citeulike.org/user/DigitalPigLee/article/2308116 <i>Macromolecules, Vol. 29, No. 10. (6 May 1996), pp. 3629-3638.</i><br /><br />Abstract: We use results on polymer absorption obtained from a recent mean-field theory with two order parameters to interpret numerical results of the Scheutjens and Fleer approach. An extension of the analytical theory accounting for the local swelling of the polymer is also presented and discussed. Adsorption of Neutral Polymers: Interpretation of the Numerical Self-Consistent Field Results A Johner J Bonet-Avalos CC van der Linden AN Semenov JF Joanny doi:10.1021/ma951637j Macromolecules, Vol. 29, No. 10. (6 May 1996), pp. 3629-3638. 2008-01-30T18:03:06-00:00 1996 Macromolecules 29 10 3629 3638 adsorption polymer simulation http://www.citeulike.org/user/ansobol/article/943121 <i>(13 Nov 2006)</i><br /><br />A cornerstone of modern polymer physics is the `Flory ideality hypothesis' which states that a chain in a polymer melt adopts `ideal' random-walk-like conformations. Here we revisit theoretically and numerically this pivotal assumption and demonstrate that there are noticeable deviations from ideality. The deviations come from the interplay of chain connectivity and the incompressibility of the melt, leading to an effective repulsion between chain segments of all sizes $s$. The amplitude of this repulsion increases with decreasing $s$ where chain segments become more and more swollen. We illustrate this swelling by an analysis of the form factor $F(q)$, i.e. the scattered intensity at wavevector $q$ resulting from intramolecular interferences of a chain. A `Kratky plot' of $q^2F(q)$ vs. $q$ does not exhibit the plateau for intermediate wavevectors characteristic of ideal chains. One rather finds a conspicuous depression of the plateau, $δ(F^-1(q)) = |q|^3/32ρ$, which increases with $q$ and only depends on the monomer density $ρ$. Why polymer chains in a melt are not random walks JP Wittmer P Beckrich J Johner AN Semenov SP Obukhov H Meyer J Baschnagel (13 Nov 2006) 2006-11-14T16:39:25-00:00 2006 polymer random-walk