MORPHOLOGY OF MODEL 3-COMPONENT 3-ARM STAR-SHAPED COPOLYMERS

The microdomain structure of a model three-component, three-arm, star- shaped copolymer consisting of polystyrene (PS), poly(dimethylsiloxane ) (PDMS) and poly(tert-butyl methacrylate) (PTBMA), each of them havin g nearly the same weight fraction, was investigated by means of differ ential scanning calorimetry (d.s.c.), transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). D.s.c. results exhibit ing the glass transition of PS and PTBMA and the crystallization and m elting of PDMS strongly suggest the microphase separation of the three components into three microdomains. The microdomain structure is cons idered to be extremely complicated because the chemical junction point s of the three constituent polymers must be confined on the lines wher e three kinds of interfaces meet. TEM and SAXS results strongly suppor t the existence of a very regular microdomain structure with three-fol d symmetry. Each of the three components possibly forms a three-dimens ionally continuous network domain resulting in an ordered tricontinuou s microdomain structure. (C) 1997 Elsevier Science Ltd.