Closed-loop phase behavior of polystyrene-block-poly(n-pentyl methacrylate) copolymers with various block length ratios

Du Yeol Ryu, Dong Hyun Lee, Unyong Jeong, Sang Hyun Yun, Soojin Park, Kyoon Kwon, Byeong Hyeok Sohn, Taihyun Chang, Jin Kon Kim, Thomas P. Russell

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Abstract

The phase behavior of polystyrene-block-poly(n-pentyl methacrylate) copolymers [PS-PnPMA] having various block length ratios was investigated by rheology, transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS). All of the PS-PnPMA exhibited two transitions: the lower disorder-to-order transition (LDOT) and upper order-to-disorder transition (UODT) occurring at a lower and higher temperature, respectively. Thus, PS-PnPMA is characterized by a closed-loop type of phase behavior. As the volume fraction of PS in PS-PnPMA was decreased from 0.5 to 0.23, the microdomains observed between the LDOT and UODT changed from lamellae (LAM) to hexagonally packed cylinders (HEX) and finally to body-centered-cubic spheres (BCC), similar to other block copolymers exhibiting only an order-to-disorder transition. The rheological properties depended strongly on the type of microdomains within the closed-loop. The storage and loss moduli (G′ and G″) within the closed loop are the highest for a PS-PnPMA having a BCC morphology, then HEX morphology, and the lowest for LAM morphology.

Original languageEnglish
Pages (from-to)3717-3724
Number of pages8
JournalMacromolecules
Volume37
Issue number10
DOIs
Publication statusPublished - 2004 May 18

All Science Journal Classification (ASJC) codes

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

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    Ryu, D. Y., Lee, D. H., Jeong, U., Yun, S. H., Park, S., Kwon, K., Sohn, B. H., Chang, T., Kim, J. K., & Russell, T. P. (2004). Closed-loop phase behavior of polystyrene-block-poly(n-pentyl methacrylate) copolymers with various block length ratios. Macromolecules, 37(10), 3717-3724. https://doi.org/10.1021/ma049746y