INQUISUR   21779
INSTITUTO DE QUIMICA DEL SUR
Unidad Ejecutora - UE
artículos
Título:
On the Supramacromolecular Structure of Core-Shell Amphiphilic Macromolecules Derived from Hyperbranched Polyethyleneimine
Autor/es:
A.S. PICCO; M. KRASKA; H. DIDZOLEIT; C. APPEL; G.F. SILBESTRI; O. AZZARONI; B. STÜHN; M. CEOLIN
Revista:
JOURNAL OF COLLOID AND INTERFACE SCIENCE
Editorial:
ACADEMIC PRESS INC ELSEVIER SCIENCE
Referencias:
Lugar: Amsterdam; Año: 2014 vol. 436 p. 243 - 250
ISSN:
0021-9797
Resumen:
The supramacromolecular structure of core?shell amphiphilic macromolecules (CAMs) with
hyperbranched polyethyleneimine (HPEI) cores and fatty acid chain shells (HPEI-Cn) for different chain
lengths was investigated both, in colloidal suspension, solid phase and at the air?water interface using
Small Angle X-ray Scattering (SAXS), Wide Angle X-ray Scattering (WAXS), X-ray Reflectometry (XRR)
and Langmuir isotherms.
At low temperatures colloidal toluene suspensions of the HPEI-Cn polymers form, as evidenced by
peaks arising in the structure factor of the system showing mean particle-to-particle distances correlated
with the length of the aliphatic chains forming the shells of HPEI-Cn unimicelles. The CAM sizes as found
from the SAXS experiments also display a clear dependence on shell thickness suggesting that the
aliphatic chains adopt a brush-like configuration.
After solvent extraction, HPEI-Cn adopts ordered structures with hexagonal packing of the aliphatic
chains.
Submitted to lateral pressure P at the air?water interface, HPEI-Cn undergoes a disorder?order
transition with increasing transition pressure for increasing chain lengths. The CAMs show different
behaviors in-plane and out-of-plane. While out-of-plane the aliphatic chains behave as a brush remaining
almost fully unfolded, whereas parallel to the air?water interface the chains fold down in a mushroom
way with increasing lateral pressure P