THERMAL AND MECHANICAL PROPERTIES OF POLYSTYRENE/POLYDIMETHYLSILOXANE BLENDS PARTIALLY COMPATIBILIZED BY STAR MOLECULES WITH A γ-CYCLODEXTRIN CORE AND POLYSTYRENE ARMS

, pharmaceuticals 4 , dyes 5 , flame retardants 6 , antibacterials 7 , insecticides 5 , and some proteins 8 . Recently star molecules containing a γ-cyclodextrin (γ-CD) core and twelve polystyrene (PS) arms have been synthesized by atom transfer radical polymerization (ATRP) within our group. One advantage γ-CD has demonstrated is its ability to thread many types of homopolymers into its interior cavity due to its larger inner core dimension of 9.5A, whereas α- and β-CD have diameters of 5.7A and 7.8A, respectively. Generally an exception to γ-CD threading has been PS, although this depends immensely on tacticity. Isotactic sequences of PS have been modeled to show that threading is possible with a cross-sectional area of 8.9A. 9 On the other hand the crosssectional diameter of 10.2A for syndiotactic PS sequences has been modeled to be too large for threading into the γ-CD cavity. Therefore an atactic PS that contains isotactic sequences on the polymer chain end will have some tendency for inclusion, but full threading of the chain is unlikely. In theory by putting PS arms on the γ-CD core the tendency for self-threading will be reduced, leaving the CD cavity open for other molecular guests such as polydimethylsiloxane (PDMS). The arms will enhance the compatibility with a PS matrix.