STAR-SHAPED CONDENSATION POLYMERS - SYNTHESIS, CHARACTERIZATION, AND BLEND PROPERTIES

A series of epsilon-caprolactone linear and star polymers were prepared and characterized in order to determine the effect of the star architecture (i.e., star number and arm length) on the morphology of these semicrystalline polymers. A spherulitic morphology was found in all the polymers investigated. However, for six arm stars containing low degrees of polymerization, it appears that the star core dominates its morphological behavior (presumably due to its relatively high volume fraction). The star core effects, however, are markedly reduced in star polymers where the arms contain higher degrees of polymerization. The impact of the star core was further explored by investigating several poly(epsilon-caprolactone) (PCL):styrene-acrylontrile copolymers (SAN) blends. In all instances, miscible blends were the result because a single compositionally dependent glass-transition temperature (T-g) was observed. A moderate elevation in the T-g of the star-shaped polymers does occur, however, compared to their linear analogs. This effect is presumably due to the inability of the SAN chains to completely mix with all segments of star structure. (C) 1993 John Wiley & Sons, Inc.