A noncubic triply periodic network morphology in poly(isoprene-b-styrene-b-ethylene oxide) triblock copolymers

Travis S. Bailey, Cordell M. Hardy, Thomas H. Epps, Frank S. Bates

Research output: Contribution to journalArticle

182 Scopus citations

Abstract

We present characterization data for linear poly(isoprene-b-styrene-b-ethylene oxide) (PI-PS-PEO) triblock copolymers containing equal volume fractions of PI and PS (fPI = fPS) and varying amounts of PEO, 0 ≤ fPEO ≤ 1/3. Detailed characterization by TEM, SAXS, dynamic mechanical spectroscopy, static birefringence, and DSC indicates three distinct morphologies: two-domain lamellae, a three-domain noncubic triply periodic network structure, and three-domain lamellae with increasing PEO content. This phase behavior is in striking contrast with the homologous PS-PI-PEO triblock phase diagram, reported earlier, which contains four different morphologies between the limiting two- and three-domain lamellae phases. Preliminary analysis suggests the noncubic network structure contains elementary units of 3-fold coordination, yet fundamentally distinct from the cubic core-shell gyroid topology previously demonstrated in PS-PI-PEO. This tentatively assigned model is a structural hybrid of the gyroid and perforated lamellar morphologies. These results provide quantitative evidence regarding the effects of block sequencing on the phase behavior of ABC triblock copolymers near the order-disorder transition.

Original languageEnglish (US)
Pages (from-to)7007-7017
Number of pages11
JournalMacromolecules
Volume35
Issue number18
DOIs
StatePublished - Aug 27 2002

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