NMR Self-Diffusion Study of Poly(ethylene oxide)-block-poly(dimethylsiloxane) Diblock Copolymers in Organic Solvents and in Poly(ethylene oxide) Melts

Zoltán Király, Terence Cosgrove, Brian Vincent

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The self-diffusion coefficients of two poly(ethylene oxide)-block-poly(dimethylsiloxane), PEO-b-PDMS, diblock copolymers (molecular weights: 2120-b-2240 and 2120-b-5340) have been measured by the pulsed field-gradient spin-echo (PFGSE) NMR technique. The solvents used were chloroform-d, toluene-d8, and tetrahydrofuran-d8 at 30 °C, cyclohexane-d12 at 50 °C, dimethylformamide-d7 (DMF) in the temperature range of 25–60 °C and protonated poly(ethylene oxide) melts of molecular weight of 222, 480, and 980 in the range of 25–150 °C. The copolymers form micelles in DMF and PEO melts and micellar break-up takes place as the temperature is raised. The temperature dependence of the critical micelle concentration in PEO melts was determined by a turbidiometric method. The hydrodynamic radii of the micelles, calculated using the Stokes-Einstein equation, were virtually independent of solvency and had a value of about 5 and 8 nm for the shorter and longer chain copolymer, respectively. The corresponding aggregation numbers were calculated to be 25 and 31.

Original languageEnglish
Pages (from-to)1258-1262
Number of pages5
JournalLangmuir
Volume9
Issue number5
DOIs
Publication statusPublished - Jan 1 1993

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ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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