End-to-end coupling and network formation behavior of cylindrical block copolymer micelles with a crystalline polyferrocenylsilane core

Siti Fairus Mohd Yusoff, Joe B. Gilroy, Graeme Cambridge, Mitchell A. Winnik, Ian Manners

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Cylindrical block copolymer micelles with a crystalline poly(ferrocenyldimethylsilane) (PFDMS) core and a long corona-forming block are known to elongate through an epitaxial growth mechanism on addition of further PFDMS block copolymer unimers. We now report that addition of the semicrystalline homopolymer PFDMS28 to monodisperse short (ca. 200 nm), cylindrical seed micelles of PFDMS block copolymers results in the formation of aggregated structures by end-to-end coupling to form micelle networks. The resulting aggregates were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). In some cases, a core-thickening effect was also observed where the added homopolymer appeared to deposit and crystallize at the core - corona interface, which resulted in an increase of the width of the micelles within the networks. No evidence for aggregation was detected when the amorphous homopolymer poly(ferrocenylethylmethylsilane) (PFEMS25) was added to the cylindrical seed micelles whereas similar behavior to PFDMS28 was noted for semicrystalline polyferrocenyldimethylgermane (PFDMG 30). This suggested that the crystallinity of the added homopolymer is critical for subsequent end-to-end coupling and network formation to occur. We also explored the tendency of the cylindrical seed micelles to form aggregates by the addition of PI-b-PFDMS (PI = polyisoprene) block copolymers (block ratios 6:1, 3.8:1, 2:1, or 1:1), and striking differences were noted. The results ranged from typical micelle elongation, as reported in previous work, at high corona to core-forming block ratios (PI-b-PFDMS; 6:1) to predominantly end-to-end coupling at lower ratios (PI-b-PFDMS; 2:1, 1:1) to form long, essentially linear structures. The latter process, especially for the 2:1 block copolymer, led to much more controlled aggregate formation compared with that observed on addition of homopolymers.

Original languageEnglish
Pages (from-to)11220-11230
Number of pages11
JournalJournal of the American Chemical Society
Volume133
Issue number29
DOIs
Publication statusPublished - 27 Jul 2011

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Micelles
Block copolymers
Homopolymerization
Crystalline materials
Seed
Seeds
Polyisoprenes
Atomic Force Microscopy
Dynamic light scattering
Transmission Electron Microscopy
Epitaxial growth
Elongation
Atomic force microscopy
Deposits
Agglomeration
Transmission electron microscopy
Growth

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

End-to-end coupling and network formation behavior of cylindrical block copolymer micelles with a crystalline polyferrocenylsilane core. / Mohd Yusoff, Siti Fairus; Gilroy, Joe B.; Cambridge, Graeme; Winnik, Mitchell A.; Manners, Ian.

In: Journal of the American Chemical Society, Vol. 133, No. 29, 27.07.2011, p. 11220-11230.

Research output: Contribution to journalArticle

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