|Title:||Synthesis of Well-Defined Block Copolymers of Hyperbranched Polyamide and Polystyrene and Their Micelle-to-Vesicle Transformation in Organic Solvents||Authors:||Ohta, Yoshihiro
Huang, Chih Feng
Lee, Yi Huan
|Keywords:||chain-growth condensation polymerization | hyperbranched polymers | linear-hyperbranched block copolymers | micelles | self-assembly | vesicles||Issue Date:||1-Jan-2023||Publisher:||WILEY-V C H VERLAG GMBH||Journal Volume:||224||Journal Issue:||1||Source:||Macromolecular Chemistry and Physics||Abstract:||
Well-defined block copolymers consisting of hyperbranched polyamide (HBPA) and polystyrene (PSt) are synthesized, and their self-assembled structures in solutions are investigated. Atom transfer radical polymerization (ATRP) of styrene initiated from an HBPA macroinitiator, prepared by the chain-growth condensation polymerization of an AB2 monomer, followed by introduction of an ATRP initiator unit at the focal point, gives the desired block copolymers, PSt-b-HBPAs, with well-defined molecular weight and narrow molecular weight distribution. The block copolymer (PSt/HBPA = 84/16) undergoes self-assembly in toluene to form spherical micelles (≈10–20 nm), but upon addition of methanol to the toluene solution (toluene/methanol = 0.97/0.03), the morphology changes to vesicles. Further addition of methanol (toluene/methanol = 0.90/0.10) leads to an increase in vesicle size (200–300 nm) and the morphology further transforms from vesicles to large aggregates (>100 nm) at toluene/methanol = 0.80/0.20. In the case of PSt-b-HBPA with shorter PSt segments (PSt/HBPA = 76/24 and 60/40), spherical micelles are formed in toluene, but the micelle morphology remains unchanged when 10 wt% methanol is added, though large aggregates (>100 nm) are still formed in toluene/methanol = 0.80/0.20. Interestingly, the morphological transformations of linear/hyperbranched block copolymers are different from those of their double linear block copolymer counterparts.
|Appears in Collections:||化學工程學系|
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