Τίτλος:
UMacromolecular architecture effects on block copolymer dynamics: Linear tetrablocks and inverse starblocks
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
Photon correlation spectroscopy and pulsed-field-gradient NMR have been used to investigate the role of different macromolecular architecture on the dynamics of block copolymer solutions in the low wavevector (q) limit using linear tetrablock (TB) and inverse starblock (SB) copolymers composed of two jointed TB's (NSB = 2NTB). The three relaxation processes observed for diblocks are also evident in the present case: the cooperative diffusion, the internal copolymer chain relaxation (q2-dependent intensity and qindependent rate), and the polydispersity diffusive mode, controlled by the self-diffusion (due to the finite composition polydispersity). The internal mode characteristics are identical for both systems at a given concentration, in agreement with theoretical estimates for Rouse chains, whereas the selfdiffusivities show the effect of the total molecular weight and the architecture. At high concentrations of the SB copolymers, there is evidence for an extra relaxation process with a strong-concentration-dependent intensity apparently due to the proximity to the ODT and due to the macromolecular architecture. © 1999 American Chemical Society.
Συγγραφείς:
Chrissopoulou, K.
Tselikas, Y.
Anastasiadis, S.H.
Fytas, G.
Semenov, A.N.
Fleischer, G.
Hadjichristidis, N.
Thomas, E.L.
Περιοδικό:
Macromolecules
Εκδότης:
American Chemical Society
Λέξεις-κλειδιά:
Chemical bonds; Composition effects; Diffusion; Macromolecules; Molecular dynamics; Molecular weight; Nuclear magnetic resonance; Numerical methods; Relaxation processes; Spectroscopy, Cooperative diffusion; Finite composition polydispersity; Internal copolymer chain relaxation; Inverse starblocks; Linear tetrablocks; Macromolecular architecture effects; Photon correlation spectroscopy; Polydispersity diffusive mode; Rouse chains, Block copolymers
