INVESTIGATION OF SURFACE ENRICHMENT IN ISOTOPIC MIXTURES OF POLY(METHYL METHACRYLATE)

The surface enrichment behavior of blends of perdeuterated poly(methyl methacrylate) with various molecular weights in a high molecular weight hydrogenous poly(methyl methacrylate) matrix has been studied using static secondary ion mass spectrometry and neutron reflectrometry. No significant enrichment was observed in any of these blends, and the results are interpreted in light of available diffusion and thermodynamic data. We conclude that the absence of surface enrichment is due to a low surface energy difference between hydrogenous poly(methyl methacrylate) and deuteropoly(methyl methacrylate) and believe this difference to be in the range 0.00-0.04 mJ m(-2). This is compared to the behavior of the hydrogenous polystyrene/deutropolystyrene blends where the surface energy difference has been calculated to be 0.08 mJ m(-2).