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Baek, Jong-Beom
Center for Dimension-Controllable Organic Frameworks
Research Interests
  • Covalent Organic Frameworks (COFs), Carbon Nanotubes(CNTs), graphene, Energy Conversion and Storage

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Carboxylic Acid-Terminated Hyperbranched Polybenzoxazole and Its Polyarm-Star Block Copolymers

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Title
Carboxylic Acid-Terminated Hyperbranched Polybenzoxazole and Its Polyarm-Star Block Copolymers
Author
Lim, Jong-KwanJeon, In-YupLyons, Christopher B.Laufersweiler, Michael C.Tan, Loon-SengBaek, Jong-Beom
Keywords
Carboxylic acid groups; Concentration of; Concentration variation; Core-shell; Emission behavior; Emission intensity; Friedel-crafts acylation; Hyperbranched; Optical behavior; Phenoxybenzoic acid; Phosphorus pentoxide; Poly (phosphoric acid); Polybenzoxazole; Polymer concentrations; Quasi-linear; Reaction medium; Sample solution; Star block copolymer; UV-vis absorptions
Issue Date
200903
Publisher
AMER CHEMICAL SOC
Citation
MACROMOLECULES, v.42, no.5, pp.1541 - 1553
Abstract
A new AB(2) monomer, 5-amino-4-hydroxyisophthalic acid hydrochloride, was synthesized and polymerized in poly(phosphoric acid) (PPA) to afford a carboxylic acid-terminated hyperbranched polybenzoxazole (HPBO). Taking advantage of the large number of peripheral carboxylic acid groups on HPBO, polyarm-star block copolymers, HPBO-b-mPEK and HPBO-b-pPEK, were conveniently prepared in the same reaction medium with additional amounts of phosphorus pentoxide (P(2)O(5)) via "direct" Friedel-Crafts acylation reaction with Sand 4-phenoxybenzoic acids as AB monomers. All the resulting polymers displayed polyelectrolyte behaviors in solution due to the large number of carboxylic acid termini. The UV-vis absorption intensities, which increased as polymer concentration was increased, showed quasi-linear dependence in all sample solutions. The emission intensity drastically decreased as the concentration of HPBO core polymer was increased, while the block copolymers were not much affected by concentration variation. The emission behaviors of HPBO-b-mPEK and HPBO-b-pPEK should be inherent to the chromophoric inner HPBO cores, which were shielded by the outer linear PEK shells. The morphology study suggested that both proton conductivity and optical behaviors of HPBO might be greatly influenced by the globular core-shell architecture.
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DOI
http://dx.doi.org/10.1021/ma802401v
ISSN
0024-9297
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