Organizational Stabilities of Bulk Neat and Well-Mixed, Blended Polymer Samples Coalesced from Their Crystalline Inclusion Compounds Formed with Cyclodextrins

Cyclodextrins (CDs) are cyclic starches containing alpha-1,4-linked glucose units. Commonly available alpha-, beta-, and gamma-CDs have six, seven, and eight glucose units, respectively. They are well known for forming noncovalent inclusion complexes (ICs) with a variety of guest molecules, including many polymers, by threading and inclusion into their relatively hydrophobic interior cavities, which are roughly cylindrical, with diameters of similar to 0.5-1.0 nm. Warm water washing of crystalline CD-ICs containing polymer guests insoluble in water or treatment with amylase enzymes serve to remove the host CDs and result in the coalescence of the guest polymers into solid bulk samples. When guest polymers are coalesced from their CD-ICs by carefully removing the host CD lattices, they are observed to solidify with structures, morphologies, and even conformations that are distinct from bulk samples made from their solutions and melts. In addition, molecularly mixed, intimate blends can be obtained upon coalescence of two or more normally immiscible polymer guests from their common CD-ICs. Not only are the organizations and behaviors of bulk polymer samples significantly modified on coalescence from their CD-ICs, but both are also maintained for significant periods of time even when heated above their T(g)s and T(m)s, where their chains are mobile. Here, we discuss the long-time, high temperature stabilities of the organizations and properties of bulk polymers coalesced from their crystalline CD-ICs. While random-coiling of their initially coalesced, largely extended, separated, and unentangled chains may be relatively rapid, we conclude that the subsequent slow establishment of homogeneous melts or phase-segregated blends results from the extremely sluggish center-of-mass diffusion that must accompany full entanglement of their chains. Apparently, the process of entangling the largely separated and not fully interpenetrating randomly coiled chains initially coalesced from their CD-ICs is particularly slow, much slower in fact than the center-of mass diffusion of polymer chains in their fully entangled melts. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1543-1553, 2009