title: More on polypseudorotaxanes formed between poly(ethylene glycol) and α-cyclodextrin.
abstract: A new interpretation for the mechanism associated with the spontaneous threading of α-CD, onto a PEG chain followed by the supramolecular hydrogel formation, is described. Beyond a specific stoichiometry, the complexation of α-CD and PEG results in the formation of a two-phase system. Besides the phase separation, for PEG with a molecular weight higher than 6000 Da, part of the polymer chains are unthreaded by the α-CD, leading to the formation of a supramolecular hydrogel. The kinetics for the complexation and the determination of the yield for equilibrated systems consisting of PEG (linear and star) are used to investigate the number of α-CD threaded before and after the phase separation. The results are compared with the prediction obtained from the application of the Poisson distribution and reveal the ratio between α-CD and PEG in each step of the process. Additionally, the kinetics for the hydrogel formation and its inner structure are investigated by using the proton NMR spin-spin relaxation of water.
authors.affiliation: Department of Physical-Chemistry, Institute of Chemistry, University of Campinas UNICAMP, Campinas, SP, Brazil. sabadini@iqm.unicamp.br
authors.forename: Edvaldo
authors.initials: E
authors.lastname: Sabadini
authors.forename: Fernanda do Carmo
authors.initials: Fdo C
authors.lastname: Egídio
authors.forename: Terence
authors.initials: T
authors.lastname: Cosgrove
mesh_terms: D011092:Polyethylene Glycols / Q000737:chemistry*; D043862:Rotaxanes / Q000737:chemistry*; D047391:alpha-Cyclodextrins / Q000737:chemistry*
chemical_list: D043862:Rotaxanes; D047391:alpha-Cyclodextrins; D011092:Polyethylene Glycols