Solid surface polymer melts simple liquids

Our restriction to simple fluids was meant to emphasize general laws and phenomena. For this reason, we did not discuss theories of the surface tension of solids, for which a variety of models have been elaborated. One of the considerations for omitting these was that such tensions cannot be measured, so that a check of the quality is edso impossible. We also consciously excluded the surface tensions of liquid metals, liquid crystals, molten crystals and polymer melts. However, spread and adsorbed polymer layers will be considered in chapter 3 and 4, respectively. For similar reasons, and because most practical applications involve ambient temperatures, we did not extensively discuss critical phenomena, notwithstanding their Intrinsic Interest. Under critical conditions the surface energy - surface entropy balance differs considerably from that at lower temperatures, emphasized in this chapter. 

This name covers all polymer chains (diblocks and others) attached by one end (or end-block) at ( external ) solid/liquid, liquid/air or ( internal ) liquid/liq-uid interfaces [226-228]. Usually this is achieved by the modified chain end, which adsorbs to the surface or is chemically bound to it. Double brushes may be also formed, e.g., by the copolymers A-N, when the joints of two blocks are located at a liquid/liquid interface and each of the blocks is immersed in different liquid. A number of theoretical models have dealt specifically with the case of brush layers immersed in polymer melts (and in solutions of homopolymers). These models include scaling approaches [229, 230], simple Flory-type mean field models [230-233], theories solving self-consistent mean field (SCMF) equations analytically [234,235] or numerically [236-238]. Also first computer simulations have recently been reported for brushes immersed in a melt [239]. 

This book is solely concerned with polymers in the amorphous state, that is polymer molecules in solution, the melt or that are intrinsically amorphous in the solid state by virtue of their chemical structure. We discuss surfaces and interfaces involving pure polymeric phases and interfaces between simple liquids and solids or air that are modified by an accumulation of polymeric molecules. The situation is in one sense more complicated than that for materials composed of atoms or small molecules. For these systems, as hinted at above, there is a single length scale characterising the range of forces between molecules and this molecular length scale dictates the range over which the perturbation imposed by an interface persists. For polymers there are... 

It should be noted that the slip of concern to this paper is that of simple Newtonian liquids against solid surfaces and not the much more widely-accepted slip that can occur when some polymer melt systems are sheared, that is believed to be due to disentanglement of polymer chains attached to the surface from those in the bulk fluid [2],... 

A tenet of textbook continuum fluid dynamics is the no-slip boundary condition, which means that the ensemble average of the velocity of fluid molecules directly at the surface of a solid is the same as the velocity of the solid. A possible slip was discussed only in the mainstream literature for complex liquids, for example, polymer melts [659,660]. Recent experiments, however, indicated that simple liquids might also slip past smooth surfaces [661-666]. 

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