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Title: Rheological Evidence of Composition Fluctuations in an Unentangled Diblock Copolymer Melt near the Order-Disorder Transition

Rheological and small-angle X-ray scattering (SAXS) measurements were conducted on a symmetric, low molar mass (Mn = 17.6 kg/mol), poly(tert-butylstyrene-block-methyl methacrylate) (PtBS-PMMA) diblock copolymer near the order–disorder transition temperature (TODT = 193 ± 1 °C). Evidence of composition fluctuations is apparent in the low frequency elastic (G') and loss (G") moduli and in the temperature dependence of the peak scattering intensity, I(q*), up to 50 °C above the TODT. These findings demonstrate that chain entanglements are not responsible for the well-documented fluctuation mode in the terminal viscoelastic regime of block copolymer melts.
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  1. UMM
Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Macro Letters; Journal Volume: 2; Journal Issue: (6) ; 06, 2013
American Chemical Society
Research Org:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
Sponsoring Org:
Country of Publication:
United States