Influence of composition fluctuations on the linear viscoelastic properties of symmetric diblock copolymers near the order-disorder transition

Robert John Hickey, III, Timothy M. Gillard, Timothy P. Lodge, Frank S. Bates

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Rheological evidence of composition fluctuations in disordered diblock copolymers near the order-disorder transition (ODT) has been documented in the literature over the past three decades, characterized by a failure of time-temperature superposition (tTS) to reduce linear dynamic mechanical spectroscopy (DMS) data in the terminal viscoelastic regime to a temperature-independent form. However, for some materials, most notably poly(styrene-b-isoprene) (PS-PI), no signature of these rheological features has been found. We present small-angle X-ray scattering (SAXS) results on symmetric poly(cyclohexylethylene-b-ethylene) (PCHE-PE) diblock copolymers that confirm the presence of fluctuations in the disordered state and DMS measurements that also show no sign of the features ascribed to composition fluctuations. Assessment of DMS results published on five different diblock copolymer systems leads us to conclude that the effects of composition fluctuations can be masked by highly asymmetric block dynamics, thereby resolving a long-standing disagreement in the literature and reinforcing the importance of mechanical contrast in understanding the dynamics of ordered and disordered block polymers.

Original languageEnglish (US)
Pages (from-to)260-265
Number of pages6
JournalACS Macro Letters
Volume4
Issue number2
DOIs
StatePublished - Feb 17 2015

Fingerprint

Order disorder transitions
Block copolymers
Chemical analysis
Spectroscopy
Isoprene
Styrene
X ray scattering
Ethylene
Temperature

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

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abstract = "Rheological evidence of composition fluctuations in disordered diblock copolymers near the order-disorder transition (ODT) has been documented in the literature over the past three decades, characterized by a failure of time-temperature superposition (tTS) to reduce linear dynamic mechanical spectroscopy (DMS) data in the terminal viscoelastic regime to a temperature-independent form. However, for some materials, most notably poly(styrene-b-isoprene) (PS-PI), no signature of these rheological features has been found. We present small-angle X-ray scattering (SAXS) results on symmetric poly(cyclohexylethylene-b-ethylene) (PCHE-PE) diblock copolymers that confirm the presence of fluctuations in the disordered state and DMS measurements that also show no sign of the features ascribed to composition fluctuations. Assessment of DMS results published on five different diblock copolymer systems leads us to conclude that the effects of composition fluctuations can be masked by highly asymmetric block dynamics, thereby resolving a long-standing disagreement in the literature and reinforcing the importance of mechanical contrast in understanding the dynamics of ordered and disordered block polymers.",
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Influence of composition fluctuations on the linear viscoelastic properties of symmetric diblock copolymers near the order-disorder transition. / Hickey, III, Robert John; Gillard, Timothy M.; Lodge, Timothy P.; Bates, Frank S.

In: ACS Macro Letters, Vol. 4, No. 2, 17.02.2015, p. 260-265.

Research output: Contribution to journalArticle

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