title: Characterization of the hidden glass transition of amorphous cyclomaltoheptaose.
abstract: An amorphous solid of cyclomaltoheptaose (β-cyclodextrin, β-CD) was formed by milling its crystalline form using a high-energy planetary mill at room temperature. The glass transition of this amorphous solid was found to occur above the thermal degradation point of the material preventing its direct observation and thus its full characterization. The corresponding glass transition temperature (T(g)) and the ΔC(p) at T(g) have, however, been estimated by extrapolation of T(g) and ΔC(p) of closely related amorphous compounds. These compounds include methylated β-CD with different degrees of substitution and molecular alloys obtained by co-milling β-CD and methylated β-CD (DS 1.8) at different ratios. The physical characterization of the amorphous states have been performed by powder X-ray diffraction and differential scanning calorimetry, while the chemical integrity of β-CD upon milling was checked by NMR spectroscopy and mass spectrometry.
authors.affiliation: Université Lille Nord de France, F-59000 Lille, France. nicolas.tabary@univ-lille1.fr
authors.forename: Nicolas
authors.initials: N
authors.lastname: Tabary
authors.forename: Aurélien
authors.initials: A
authors.lastname: Mahieu
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Willart
authors.forename: Emeline
authors.initials: E
authors.lastname: Dudognon
authors.forename: Florence
authors.initials: F
authors.lastname: Danède
authors.forename: Marc
authors.initials: M
authors.lastname: Descamps
authors.forename: Maryse
authors.initials: M
authors.lastname: Bacquet
authors.forename: Bernard
authors.initials: B
authors.lastname: Martel
mesh_terms: D005898:Glass / Q000737:chemistry*; D044367:Phase Transition; D044366:Transition Temperature; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D047392:beta-Cyclodextrins; C031215:betadex