Programmed thermodynamic formation and structure analysis of star-like nanogels with core cross-linked by thermally exchangeable dynamic covalent bonds

Yoshifumi Amamoto, Yuji Higaki, Yasuhiro Matsuda, Hideyuki Otsuka, Atsushi Takahara

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Programmed thermodynamic formation of star-like nanogels from designed diblock copolymers with thermally exchangeable dynamic covalent bonds in their side chains and structure analysis of the nanogels were performed. Linear diblock copolymers that consist of poly(methyl methacrylate) block and random copolymer block of methyl methacrylate (MMA) and methacrylic esters with alkoxyamine moiety were prepared by atom transfer radical polymerization (ATRP). By heating the diblock copolymers in anisole, a cross-linking reaction occurred as a result of the radical crossover reaction of alkoxyamine moieties to afford star-like nanogels. Kinetic studies have revealed that the cross-linking behavior reaches equilibrium at a given reaction time, with characteristic reaction behaviors for thermodynamic reactions being observed. The equilibrium structures of the star-like nanogels were controlled by the initial concentrations of diblock copolymers as well as their compositions and molecular weights. Furthermore, by heating the star-like nanogels with excess alkoxyamine, linear polymers were successfully regenerated. The molecular weights and sizes of the nanogels were evaluated by gel permeation chromatography-multiangle laser light scattering (GPC-MALLS) and small-angle X-ray scattering (SAXS) measurements, respectively, and the morphologies of the nanogels were directly observed by scanning force microscopy (SFM).

Original languageEnglish
Pages (from-to)13298-13304
Number of pages7
JournalJournal of the American Chemical Society
Issue number43
Publication statusPublished - Oct 31 2007


All Science Journal Classification (ASJC) codes

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

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