Supramolecular Pseudorotaxane Graft Copolymer from a Crown Ether Polyester and a Complementary Paraquat-Terminated Polystyrene Guest
(5987–5993) Macromolecules 44 #15 (2011)
Lee, Moore and Gibson of Virginia Polytechnic Institute & State University, Virginia, usedself-assembly of a polyester containing crown ether host repeat units and a paraquat-terminated polystyrene guest to produce a supramolecular pseudorotaxane graft copolymer based on the bis(m-phenylene)-32-crown-10/paraquat recognition motif. NMR chemical shift changes in solution gave evidence of the complexation of the crown ether and paraquat moieties.  Solutions of the two polymers at 1:1 host:guest stoichiometry (crown ether:paraquat), but only 3 mass % crown polymer, possessed an intrinsic viscosity 1.9 times that of the paraquat-terminated polystyrene and 2.7 times that of the polyester.  Differential scanning calorimetry revealed only one glass transition for a solid from evaporation of a solution at 3:1 host:guest (crown ether:paraquat) stoichiometry; this indicated complete phase mixing, as confirmed by optical microscopy and small-angle laser light scattering.  (RDC 8/2/2011)