Conformations_Brushes_surfaces_Macromolecules_deGennes_1980_ma60077a009

Conformations_Brushes_surfaces_Macromolecules_deGennes_1980_ma60077a009

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Macromolecules 1980,13,1069-1075 1069 (19) Duiek, K. J. Polym. Sci., Polym. Phys. Ed. 1974, 12, 1089. Symp., 1975,53, 29. (21) Durand, D.; Bruneau, C. M. Polym. Sci., Polym. Phys. Ed. 1979, 17, 295. (22) Gordon, M.; Parker, T. G. Proc. R. SOC. Edinburgh 1970,69, 13. (23) Kajiwara, K.; Burchard, W.; Gordon, M. Br. Polym. 1970, (24) Burchard, W. Macromolecules 1972,5, 604. (25) Muller, M.; Burchard, W. Makromol. Chem. 1978,179, 1821. (26) Ross, S. M. “Introduction to Probability Models”; Academic Press: New York, 1972; Chapter 3. (27) Duiek, K. Makromol. Chem., Suppl. 1979,2,35. (20) Duiek, K.; Ilavsky, M.; Lunak, S. Polym. Sci., Polym. 2, 110. Conformations of Polymers Attached to an Interface P. G. de Gennes CollGge de France, 75231 Paris Cedex 05, France. Received April 10, 1980 ABSTRACT We discuss the conformations and the concentration profiles for long, flexible chains (N monomers per chain) grafted at one end on a solid surface (fraction of surface sites grafted u). The chains are immersed either in a pure (good) solvent or in a solution of the same polymer (P monomers per mobile chain, volume fraction 4). It is assumed that the polymer does not adsorb on the wall surface. The zone occupied by the grafted chain may contain a large fraction of mobile P chains: we call this a mixed case (M), as opposed to the unmixed case (UM). Also the chains may be stretched (S) or unstretched (US). The combination of these two criteria gives four possible regimes. Using scaling laws, we locate the domains of existence of these four regimes in terms of the variables u and 6. High u values may be hard to reach by grafting but could be obtained with block copolymers at an interface between two immiscible solvents. I. Introduction Polymers grafted onto solid walls can be useful for many physicochemical applications:’ wetting, adhesion,2 chro- matography: colloid stabilization,4 and biocompatibility5 are typical examples. In the present paper, we discuss theoretically some conformation problems for grafted, flexible polymers immersed in good solvents. The situation which we have in mind is described on Figure 1: here, a set of linear chains (with N monomers per chain) is atta- ched to a wall and immersed in a liquid which may be either a pure solvent or, more generally, a solution of the same polymer (with P monomers per chain). We assume that all chains are uncharged: this eliminates some im- portant practical situations but is logical in view of the difficulties found in understanding polyelectrolyte con- formations in solution. We also assume no adsorption: the chains are not attracted to the wall. The opposite case can be treated and has in fact been discussed in some limits6 but is obscured by the increase in number of relevant parameters. A global Flory-Huggins theory for the selective prop- erties of a set of grafted chains with respect to solvent mixtures has recently been constructed.’ Our aim here is somewhat different: (a) We are mainly concerned with conformational properties and with spatial distributions.
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Conformations_Brushes_surfaces_Macromolecules_deGennes_1980_ma60077a009

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