Copolymer−Cyclodextrin Inclusion Complexes in Water and in the Solid State. A Physico-Chemical Study

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Abstract

The formation of inclusion complexes (ICs) composed of cyclodextrins (CDs) and poly(ethyleneoxides)-poly(propylene oxides)-poly(ethylene oxides) (PEO-PPO-PEO) was studied. To this purpose,native and hydroxypropyl cyclodextrins with different cavity size were chosen. The PEO-PPO-PEOcopolymers were selected to study the role of the molecular weight, keeping constant the hydrophilic/hydrophobic ratio, and the hydrophilicity. The volumetric studies at 25 °C allowed to determine the equilibriumconstant and the volume change for the IC formation in water as well as the IC stoichiometry. Surface tensionexperiments evidenced that the copolymer and the CD interfacial behavior is controlled by the formation ofICs taking place in the bulk phase. It was proved that the differential scanning calorimetry (DSC) is a validmethod to describe quantitatively the IC in the solid state. The combination of volumes, DSC and FTIRtechniques together with the geometric information highlighted the following points: (1) the included copolymeris in the amorphous state; (2) the IC composed of native CDs adopts a channel structure with two EO unitsincorporated into one CD molecule; (3) the IC composed of hydroxypropyl-cyclodextrin is a polymericstructure like a necklace decorated with CD rings. Finally, TGA experiments showed that the thermal stabilityof the IC depends on the nature of both components.
Lingua originaleEnglish
pagine (da-a)11887-11895
Numero di pagine9
RivistaJOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL
Volume112
Stato di pubblicazionePublished - 2008

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All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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