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

Journal Article · Thu Feb 13 04:00:00 EST 2014 · ACS Macro Letters

DOI:https://doi.org/10.1021/mz4001892· OSTI ID:1095355

Kennemur, Justin G.; Hillmyer, Marc A.; Bates, Frank S. ^[1]

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1. UMM

Rheological and small-angle X-ray scattering (SAXS) measurements were conducted on a symmetric, low molar mass (M_n = 17.6 kg/mol), poly(tert-butylstyrene-block-methyl methacrylate) (PtBS-PMMA) diblock copolymer near the order–disorder transition temperature (T_ODT = 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 T_ODT. These findings demonstrate that chain entanglements are not responsible for the well-documented fluctuation mode in the terminal viscoelastic regime of block copolymer melts.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: INDUSTRY
• OSTI ID: 1095355
• Journal Information: ACS Macro Letters, Journal Name: ACS Macro Letters Journal Issue: (6) ; 06, 2013 Vol. 2; ISSN 2161-1653
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: ENGLISH