Microstructure Effects on the Lower Critical Solution Temperature Phase Behavior of Deuterated Polybutadiene and Protonated Polyisoprene Blends Studied by Small-Angle Neutron Scattering

Shinichi Sakurai, Hiroshi Jinnai, Hirokazu Hasegawa, Takeji Hashimoto, Charles C. Han

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

The miscibility of a blend of protonated polyisoprene (HPI) with the 3, 4-linkage microstrucure in the range 7–15% and of deuterated polybutadiene (DPB) with the 1,2-linkage microstructure in the range 12–28% was studied by small-angle neutron scattering (SANS). It was found that all blends studied here show lower critical solution temperature (LCST) type phase behaviors; i.e., the phase separation occurs by raising the temperature. It was also found that the miscibility is quite sensitive to the microstructures of the polydienes used. The effective thermodynamic interaction parameter xoff per segment between two polymers was determined by fitting SANS data in the single-phase state with a theoretical scattering curve obtained on the basis of the random-phase approximation. The temperature dependence of xoff showed a systematic change with the microstructure. For a given HPI, the xoff values decreased, and therefore, the blends became more miscible, with an increase in the vinyl content (i.e., 1,2-linkage content) in DPB. On the contrary, for a given DPB, the values increased, and therefore, the blends became more immiscible, with an increase in the vinyl content (i.e., 3,4-linkage content) in HPI. We proposed an alternative explanation for the LCST phase behavior based on treatment for the random copolymer blends.

Original languageEnglish
Pages (from-to)4839-4843
Number of pages5
JournalMacromolecules
Volume24
Issue number17
DOIs
Publication statusPublished - 1991 Aug 1
Externally publishedYes

ASJC Scopus subject areas

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

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