Grafted polymer tail loop mixtures differing in chain length

Studies examining the structure of monolayers formed by polymer chains graf ted to a surface typically focus on chains attached at one end (tails). Bon d fluctuation simulations are performed here to probe monolayers composed o f equimolar mixtures of tails and double-grafted loops in which the looped chain length (N-loop) is varied at constant surface density and tail length (N-tail). Loops force the tails to adopt an extended trajectory normal to the surface, resulting in monolayer stratification. As N-loop increases, th e height of the tail sublayer increases to a maximum, and then decreases to converge with the loop sublayer as N-loop --> 2N(tail). These results are compared to predictions from a self-consistent field theory for bidisperse mixtures of grafted tails. (C) 1999 Elsevier Science Ltd. All rights reserv ed.