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Polymer dynamics in block copolymer melts with different morphologies

AuthorsLund, Reidar; Barroso-Bujans, Fabienne ; Alegría, Ángel ; Moreno Segurado, Ángel J. ; Willner, Lutz; Richter, Dieter; Colmenero de León, Juan
Issue Date2013
Citation7th International Discussion Meeting on Relaxations in Complex Systems (2013)
AbstractIt is well known that block copolymers spontaneously microphase separate into well-defined geometries in the nanometer range. Such systems are interesting templates to study fundamental effects of confinement and interfaces on polymer dynamics. Here we investigate a series of well-defined poly(isoprene)-b-poly(dimethylsiloxane) (PI-PDMS) block copolymer of different molecular weights and compositions that form either spherical, cylindrical or lamellar structures. The general dynamics of these block copolymers has been studied by broadband dielectric spectroscopy (BDS) and neutron spin-echo spectroscopy (NSE). BDS results show that the alpha relaxation is generally broadened and accelerated in the micro-segregated state. The rawdata shows that there is an apparent acceleration of the “normal mode” in the case of the cylindrical and spherical phases. For the lamellar phases however, we detect a biomodal relaxation with a slow mode appearing in addition to the Rouse (internal mode) relaxation. By comparison with results from bead-spring simulations, we attribute the latter to interfacial dynamics. We also applied NSE and various contrast variation schemes to probe the dynamics of cylindrical phases. The results show that the dynamics is essentially dominated by restricted Rouse motion modulated by interface fluctuations and confined to 2-D motion along the cylinder axis. In the talk we will review results both from BDS and neutron scattering and discuss the detailed dynamics in these system.
DescriptionResumen del póster presentado al 7th International Discussion Meeting on Relaxations in Complex Systems: "New results, Directions and Opportunities", celebrado en Barcelona (España) del 21 al 26 de julio de 2013.
Appears in Collections:(CFM) Comunicaciones congresos
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