Synthesis and aggregation behavior of four-arm star amphiphilic block copolymers in water

Whittaker, M. R. and Monteiro, M. J. (2006) Synthesis and aggregation behavior of four-arm star amphiphilic block copolymers in water. Langmuir, 22 23: 9746-9752. doi:10.1021/la0616449


Author Whittaker, M. R.
Monteiro, M. J.
Title Synthesis and aggregation behavior of four-arm star amphiphilic block copolymers in water
Journal name Langmuir   Check publisher's open access policy
ISSN 0743-7463
Publication date 2006-01-01
Sub-type Article (original research)
DOI 10.1021/la0616449
Volume 22
Issue 23
Start page 9746
End page 9752
Total pages 7
Place of publication Washington, U.S.
Publisher American Chemical Society
Collection year 2006
Language eng
Subject C1
250501 Synthesis of Macromolecules
780103 Chemical sciences
Abstract We report the first synthesis of amphiphilic four-arm star diblock copolymers consisting of styrene (STY) and acrylic acid (AA) made using reversible addition-fragmentation chain transfer (RAFT; Z group approach with no star-star coupling). The polymerization proceeded in an ideal living manner. The size of the poly(AA(132)-STYm)(4) stars in DMF were small and close to 7 nm, suggesting no star aggregation. Slow addition of water (pH = 6.8) to this mixture resulted in aggregates of 15 stars per micelle with core-shell morphology. Calculations showed that the polyAA blocks were slightly extended with a shell thickness of 15 nm. Treatment of these micelles with piperidine to cleave the block arms from the core resulted in little or no change on micelle size or morphology, but the polyAA shell thickness was close to 29 nm (33 nm is the maximum at full extension) suggesting a release of entropy when the arms are detached from the core molecule. In this work we showed through the use of star amphiphilic polymers that the micelle size, aggregation number, and morphology could be controlled.
Keyword Chemistry, Physical
Fragmentation Chain-transfer
Cross-linked Nanoparticles
Living Radical Polymerization
Molecular-weight
Nanostructured Materials
Raft Process
Micelles
Micellization
Polymers
Q-Index Code C1

 
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Created: Wed, 15 Aug 2007, 19:17:37 EST