Segmental Rearrangements of PMMA during Adsorption

The conformational rearrangement of adsorbing chains of polymethyl methacrylate was monitored spectroscopically during the earliest phases of adsorption. The number and fraction of chain segments associated within 3 Å of the surface was found to go through a maximum corresponding to saturation of available surface sites. At this stage, the high bound fraction (0.66) is indicative of a severe distortion of the chain from its isotropic conformation. The adsorption of further macromolecules liberates a large number of previously bound segments, which presumably enables the chains to adopt more favored, random conformations.