INVESTIGADORES
PUIG julieta
artículos
Título:
Evolution of morphologies of a PE-b-PEO block copolymer in an epoxy solvent induced by polymerization followed by crystallization-driven self-assembly of PE blocks during cooling
Autor/es:
J. PUIG; I. A. ZUCCHI; M. CEOLÍN; W. F. SCHROEDER; R. J. J. WILLIAMS
Revista:
RSC Advances
Editorial:
RSC
Referencias:
Lugar: Londres; Año: 2016 vol. 6 p. 34903 - 34912
Resumen:
Polymerization-induced nanostructuration combined with crystallization-driven self-assembly was used togenerate complex nanostructures in an epoxy network. A PE-b-PEO block copolymer (Mn ¼ 1400; 50 wt%PEO), was dispersed in diglycidylether of bisphenol A (DGEBA) and homopolymerization initiated bya tertiary amine was carried out at 120 C (above the melting temperature of PE). The plasticizationproduced by the miscible PEO blocks decreased the Tg of the cured matrix to values located below thecrystallization temperature of PE. Therefore, crystallization-driven self-assembly of PE blocks took placeduring the cooling step through the rubbery region of the epoxy network. Depending on the initialamount of PE-b-PEO dispersed in DGEBA, a variety of nanostructures could be generated, such asa dispersion of disk-like micelles (6.7 nm in thickness), a concentrated dispersion of short nanoribbons(50?200 nm in length and 6.7 nm in thickness), partially stacked and oriented in space, and complexspherulitic structures composed of large stacked nanoribbons. The thickness of micellar objects wasclose to the theoretical value of fully extended PE chains of the block copolymer. IR spectroscopyconfirmed the all-trans conformation of PE chains. Therefore, crystals were formed by interdigitated PEchains, with PEO blocks tethered at both planar interfaces in an alternating way. The way in which thesecomplex nanostructures affect the fracture resistance or functional properties (such as shape memory)of the resulting epoxy networks has yet to be analyzed.