CRYSTALLINE POLYMER INCLUSION-COMPOUNDS - POTENTIAL MODELS FOR THE BEHAVIOR OF POLYMER-CHAINS IN THEIR BULK, ORDERED PHASES

Several small-molecule hosts form clathrates or inclusion compounds (I Cs) with polymers. In these polymer ICs the guest polymer chains are c onfined to occupy narrow channels in the crystalline matrix formed by the host. The walls of the IC channels are formed entirely from the mo lecules of the host, and they serve to create a unique solid-state env ironment for the included polymer chains. Each polymer chain included in the narrow, cylindrical IC channels (ca. 5.5 angstrom in diameter) is highly extended and also separated from neighbouring polymer chains by the host matrix channel walls. The net result is a solid-state env ironment where extended, stretched (as a consequence of being squeezed ) polymer chains reside in isolation from their neighbours inside the narrow channels of the crystalline matrix provided by the small-molecu le host. Comparison of the behaviour of isolated, stretched polymer ch ains in their crystalline ICs with observations made on ordered, bulk samples of the same polymer are beginning to provide some measure of t he contributions made by the intrinsic nature of a confined polymer ch ain and the pervasive, cooperative, interchain interactions which can complicate the behaviour of bulk polymer samples. In the same way that dilute polymer solutions at the THETA temperature have been effective ly used to model disordered, bulk polymer phases (both glasses and mel ts), polymer ICs may be utilized to increase our understanding of the behaviour of polymer chains in their ordered, bulk phases, such as tho se found in crystalline and liquid-crystalline samples.