EFFECT OF POLYMER COMPOSITION ON THE MORPHOLOGY OF SELF-ASSEMBLED DIBENZYLIDENE SORBITOL

Three-dimensional networks resulting from self-assembled dibenzylidene sorbitol (DBS) in poly(dimethylsiloxane) (PDMS) polymers have been isolated using supercritical fluid extraction and imaged with field-emission scanning electron microscopy. In pure PDMS, DBS organizes into loosely connected fibrils and fibrillar bundles 70 nm to 2 mu m thick and tens of micrometerss long. Chemical incorporation of poly(oxyethylene) grafts along the PDMS backbone yields layered sheets of DBS, whereas grafted poly(oxypropylene) promotes the formation of a percolation network in which connective fibrils measure 10-20 nm in diameter. Such morphological variations reflect molecular interactions between DBS and the dissimilar monomer sequences in each polymer.