Effects of annealing on the5 surface composition and morphology of PS/PMMA blend

C. Ton-That, A. G. Shard, R. Daley, R. H. Bradley*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    127 Citations (Scopus)


    Films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) blend have been annealed at a temperature above their glass transition temperatures for up to 48 h. Surface chemical compositions of the cast and annealed films were measured by X-ray photoelectron spectroscopy (XPS) while surface topographical changes were followed by atomic force microscopy (AFM). The blend films spin-cast from chloroform produce nonequilibrium surfaces with a significant excess of PMMA. The polymer component with a lower surface free energy, PS, is shown to segregate to the surface upon annealing. The PS surface concentration of the films, containing 50% PS:50% PMMA in the bulk, was evaluated using the ester peak in XPS C Is spectra (sampling depth ~ 9 nm) and found to increase from ~5% (freshly spin-cast film) to a saturated level of ~47% after 17 h of annealing. AFM imaging reveals evolution of blend morphology with annealing time. The spin-cast films prior to annealing exhibit pitted topography with typical pit size of ~1.2 /im and depth of 30-40 nm. As the annealing process proceeds, these pits get continually shallower. Frictional force microscopy with hydroxylated tips recorded surface phase separations for the films of 2-4 h annealing. As the annealing continues to above 14 h, the pitted structure becomes distorted. The surface enrichment and morphology changes upon annealing are explained by dewetting of PMMA relative to PS.

    Original languageEnglish
    Pages (from-to)8453-8459
    Number of pages7
    Issue number22
    Publication statusPublished - 1 Oct 2000

    ASJC Scopus subject areas

    • Organic Chemistry
    • Polymers and Plastics
    • Inorganic Chemistry
    • Materials Chemistry


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