Effect of loop/bridge conformation ratio on elastic properties of the sphere-forming ABA triblock copolymers: Preparation of samples and determination of loop/bridge ratio

Atsushi Takano, Ichiro Kamaya, Yoshiaki Takahashi, Yushu Matsushita

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

To determine the loop/bridge ratio of an ABA triblock copolymer, dynamic viscoelastic measurements were carried out using a polystyrene-block- polyisoprene-block-polystyrene triblock copolymer (SIS), a cyclic SI diblock copolymer (cyclic-SI), and a polystyrene-block-polyisoprene-block-poly(2- vinylpyridine) triblock copolymer (SIP), which were carefully synthesized by the anionic polymerization technique. The three copolymers show similar microphase-separated structures having spherical domains of S and/or P. By blending cyclic-SI and SIS, samples having various loop/bridge conformation ratios were prepared, and the SIP sample was also used as the 100% bridged reference sample. From the dynamic elongational measurements for a series of blended samples and SIP, it was confirmed that the storage modulus (E′) is the highest for the SIP, and it linearly decreases with increase of cyclic-SI content. From quantitative analysis of the results, we determined that the bridge fraction, Φbridge, in SIS triblock copolymer is 0.93. Although this fraction is significantly higher than the theoretically predicted value and the reported value from dielectric relaxation measurements, the estimated bridge fraction in the present work includes the total contribution from bridged chains and looped chains with interlocked entanglements. Furthermore, it was confirmed that breaking stresses are proportional to the effective bridge fraction in the samples.

Original languageEnglish
Pages (from-to)9718-9723
Number of pages6
JournalMacromolecules
Volume38
Issue number23
DOIs
Publication statusPublished - Nov 15 2005

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Block copolymers
Conformations
Polystyrenes
Polyisoprenes
Anionic polymerization
Dielectric relaxation
Copolymers
Elastic moduli
Chemical analysis

All Science Journal Classification (ASJC) codes

  • Materials Chemistry

Cite this

Effect of loop/bridge conformation ratio on elastic properties of the sphere-forming ABA triblock copolymers : Preparation of samples and determination of loop/bridge ratio. / Takano, Atsushi; Kamaya, Ichiro; Takahashi, Yoshiaki; Matsushita, Yushu.

In: Macromolecules, Vol. 38, No. 23, 15.11.2005, p. 9718-9723.

Research output: Contribution to journalArticle

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