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Dendrimers as scaff...
Dendrimers as scaffolds for reversible addition fragmentation chain transfer (RAFT) agents : A route to star-shaped block copolymers
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Hao, X. J. (författare)
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- Malmström, Eva (författare)
- KTH,Fiber- och polymerteknologi
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Davis, T. P. (författare)
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Stenzel, M. H. (författare)
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Barner-Kowollik, C. (författare)
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(creator_code:org_t)
- 2005
- 2005
- Engelska.
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Ingår i: Australian journal of chemistry (Print). - 0004-9425 .- 1445-0038. ; 58:6, s. 483-491
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Star-shaped block copolymers of styrene and n-butyl acrylate having three, six, and twelve pendent arms were successfully synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. Dendritic cores ( based on 1,1,1-trimethylolpropane) of generation 0, 1, and 2 have been functionalized with 3-benzylsulfanylthiocarbonylsulfanylpropionic ester groups and have subsequently been employed to mediate the polymerization of styrene and n-butyl acrylate to generate macro-star-RAFT agents as starting materials for chain extension. The chain extension of the macro-star-RAFT agents with either styrene or n-butyl acrylate by bulk free radical polymerization at 60 degrees C gives narrowly distributed polymer (final polydispersities close to 1.2) increasing linearly in molecular weight with increasing monomer-to-polymer conversion. However, with an increasing number of arms (i.e., when going from three- to twelve-armed star polymers), the chain extension becomes significantly less efficient. The molecular weight of the generated block copolymers was assessed using H-1 NMR spectroscopy as well as size exclusion chromatography calibrated with linear polystyrene standards. The hydrodynamic radius, R-h, of the star block copolymers as well as the precursor star polymers was determined in tetrahydrofuran by dynamic light scattering (90 degrees) at 25 degrees C. Interestingly, the observed R-h-M-n relationships indicate a stronger dependence of R-h on M-n for poly(butyl acrylate) stars than for the corresponding styrene polymers. R-h increases significantly when the macro-star-RAFT agent is chain extended with either styrene or n-butyl acrylate.
Ämnesord
- NATURVETENSKAP -- Kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences (hsv//eng)
Nyckelord
- free-radical polymerization
- gpc-distribution coefficients
- dendritic macromolecules
- molecular architecture
- living polymerization
- methyl-methacrylate
- spherical pores
- graft polymers
- ab-initio
- styrene
- Chemistry
- Kemi
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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