Polymers Grafted onto Strongly Adsorbing Surfaces in Poor Solvents: Stretching, Fission, Phase Separation, and Globular Micelles in 2D

Using both analytic theory and computer simulation we study the stretching along the surface of a strongly adsorbed polymer chain. In marked contrast to the case of nonadsorbed chains we show that the polymer does not undergo a Rayleigh instability. Instead it deforms steadily into a lens shape. Our results have dramatic consequences for submonolayer films formed from grafted chains. We show that strongly adsorbed chains do not form ``octopus'' or pinned micelles. Instead they fuse into compact islands, which in the limit of high grafting density can form a continuous network.