Facile synthesis of dumbbell-shaped dendritic-linear-dendritic triblock copolymer via reversible addition-fragmentation chain transfer polymerization

Zhishen Ge, Daoyong Chen, Jingyan Zhang, Jingyi Rao, Jun Yin, Di Wang, Xuejuan Wan, Wenfang Shi, Shiyong Liu

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We report the first instance of facile synthesis of dumbbell-shaped dendritic-linear-dendritic triblock copolymer, [G-3]-PNIPAM-[G-3], consisting of third generation poly(benzyl ether) monodendrons ([G-3]) and linear poly(N-isopropylacrylamide) (PNIPAM), via reversible addition-fragmentation chain transfer (RAFT) polymerization. The key step was the preparation of novel [G-3]-based RAFT agent, [G-3]-CH2SCSSCH2-[G-3] (1), from third-generation dendritic poly(benzyl ether) bromide, [G-3]-CH2Br. Due to the bulky nature of [G-3]-CH2Br, its transformation into trithiocarbonate 1 cannot go to completion, a mixture containing ∼80 mol % of 1 and 20 mol % [G-3]-CH2Br was obtained. Dumbbell-shaped [G-3]-PNIPAM310-[G-3] triblock copolymer was then successfully obtained by the RAFT polymerization of N-isopropylacylamide (NIPAM) using 1 as the mediating agent, and trace amount of unreacted [G-3]-CH2Br was conveniently removed during purification by precipitating the polymer into diethyl ether. The dendritic-linear-dendritic triblock structure was further confirmed by aminolysis, and fully characterized by gel permeation chromatography (GPC) and 1H-NMR. The amphiphilic dumbbell-shaped triblock copolymer contains a thermoresponsive PNIPAM middle block, in aqueous solution it self-assembles into spherical nanoparticles with the core consisting of hydrophobic [G-3] dendritic block and stabilized by the PNIPAM central block, forming loops surrounding the insoluble core. The micellar properties of [G-3]-PNIPAM310-[G-3] were then fully characterized.

Original languageEnglish
Pages (from-to)1432-1445
Number of pages14
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Issue number8
Publication statusPublished - 2007 Apr 15
Externally publishedYes



  • Block copolymers
  • Dendrimers
  • Reversible addition-fragmentation chain transfer (RAFT)
  • Self-assembly

ASJC Scopus subject areas

  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry

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