DISTRIBUTION OF CHAIN-ENDS AT THE SURFACE OF A POLYMER MELT - COMPENSATION EFFECTS AND SURFACE-TENSION

We consider the surface of a nearly incompressible polymer melt, exten ding the usual ground-state analysis of self-consistent field theory t o describe finite length polymers in the ground-state potential. To ma intain self-consistency, further corrections to the potential are calc ulated within linear response theory. From this, we find an excess of ends near the surface, followed by a compensating depletion on the R(g ) length scale, which relies crucially on the finite compressibility o f the melt. The attraction of ends to the surface can be described as resulting from a surface potential for ends with a strength on the ord er of k(B)T. Our results address the long-standing controversies of th e distribution of chain ends, the chain-length dependence of the surfa ce tension, and the interaction between objects immersed in a melt. (C ) 1995 John Wiley & Sons, Inc.