Interfacial Segregation in Two-Phase Polymer Blends with Diblock Copolymer Additives: The Effect of Homopolymer Molecular Weight

Kevin H. Dai, Edward J. Kramer*, Kenneth R. Shull

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

114 Scopus citations

Abstract

Segregation to interfaces in two-phase blends containing diblock copolymers is fundamental to understanding the properties of these interfaces. In this study, the effect of homopolymer molecular weight on the segregation is examined by forward recoil spectrometry (FRES). In the case of P a > N a . where P a and N a are the polymerization indices of the homopolymer A and the A block of the copolymer, respectively, it is found that the interfacial areal density of block copolymer chains (v i ) saturation is not affected significantly by P a . This situation corresponds to the case where the “brush” of A block chains is not penetrated strongly by the A homopolymer, the so-called dry brush case. However, a lower v i is observed in the case of P a < N a , the so-called wet brush case. While Leibler's brush theory 1 can reproduce the shape of the segregation isotherm if the Flory interaction parameter ϰ is allowed to vary with P a , a self-consistent meanfield theory 2 can predict the observed isotherm using a single value of ϰ. The critical micelle concentration, ϕ cmc is obtained from the onset of surface segregation and is found to decrease as the molecular weight of the homopolymer matrix increases.

Original languageEnglish (US)
Pages (from-to)220-225
Number of pages6
JournalMacromolecules
Volume25
Issue number1
DOIs
StatePublished - Jan 1 1992

ASJC Scopus subject areas

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

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