INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
artículos
Título:
Nanoribbons with semicrystalline core dispersed in a visible-light photopolymerized epoxy network
Autor/es:
ILEANA A. ZUCCHI; WALTER F. SCHROEDER
Revista:
POLYMER
Editorial:
ELSEVIER SCI LTD
Referencias:
Lugar: Amsterdam; Año: 2015 vol. 56 p. 300 - 308
ISSN:
0032-3861
Resumen:
It has been well documented that self-assembly of block copolymers (BCP)
in selective solvents, where the core-forming block is a crystallizable
polymer, results in micelle structures with exceptional aggregation
morphologies determined mainly by the crystallization energy from the
core. In this contribution, we apply this concept to create ribbon-like
nanostructures dispersed in an epoxy network. The selected system was a
polyethylene-b-poly(ethylene oxide) (PE-b-PEO) diblock
copolymer in an epoxy monomer based on diglycidyl ether of bisphenol A
(DGEBA). This system was selected on the bases that PEO is an
epoxy-philic block which is completely miscible with DGEBA before and
after curing reaction whereas PE is a crystallizable epoxy-phobic block.
Under these conditions, we access to self-assembled nanostructures with
semicrystalline core before curing reaction. With the aim of preserving
the structural features of these micelles, the epoxy monomers were
cured at room temperature (i.e., below the melting transition of the
core-forming PE block) by photoinitiated cationic ring-opening
polymerization. Long nanoribbons dispersed in the cured epoxy matrix
were obtained, as characterized by SAXS patterns and TEM images. These
ribbon-like micelles present a tendency to aggregate resulting in the
formation of face-to-face stacking of parallel micelles. We demonstrated
that while the stacking number decreases with decreasing BCP
concentration, the arrangement of the nanoribbons within one stack
becomes less organized.