IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
artículos
Título:
Solid-state studies of the crystalline/amorphous character in linear Poly(ethylenimine hydrochloride) (PEI.HCl) polymers and their copper complexes
Autor/es:
J. M. LÁZARO MARTÍNEZ; E. RODRÍGUEZ-CASTELLÓN; D. VEGA; G. A. MONTI; A. K. CHATTAH
Revista:
MACROMOLECULES
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2015 vol. 48 p. 1115 - 1125
ISSN:
0024-9297
Resumen:
Linear poly(ethylenimine hydrochloride) (PEI·HCl) polymers with different molecular weights (22, 87, and 217 kDa) and their copper complexes (Cu−PEI) were studied with particular attention to the crystalline/amorphous character of the polymeric chains in lyophilized and crystallized samples by using 1D and 2D solid-state nuclear magnetic resonance, X-ray photoelectron spectroscopy, and X-ray diffraction techniques. Different 13C{1H} cross-polarization and magic angle spinning experiments using delayed contact time, 1H dipolar filter and 1H spin-lock filter were crucial to determine the different mobility domains in the crystallized and lyophilized samples of PEI·HCl and Cu−PEI. 13C direct polarization experiments allowed the quantification of the crystalline/amorphous segments in each sample. The lyophilization process produced an increase in the amorphous fraction, even when some ordered domains were present, whereas the coordination of copper/sulfate ions produced a significant decrease in the mobility of polymer chains, leading to homogeneous and ordered materials even when Cu was desorbed.