Synthesis and self-assembly in aqueous solution of amphiphilic diblock copolymers containing hyperbranched polyethylene

- Two well-defined linear-hyperbranched diblock copolymers were synthesized.
- The diblock copolymers consist of a long HBPE block and a short water-soluble block.
- They have been found to self-assemble into vesicles in aqueous solution.
- A clear structural characterization was provided for the hydrated state vesicles.
- The vesicles showed a morphology transition when they became dried on mica surface.

In this paper, the well-defined amphiphilic diblock copolymers, hyperbranched polyethylene-b-poly(ethylene oxide) (HBPE-b-PEO) and hyperbranched polyethylene-b-poly(acrylic acid) (HBPE-b-PAA), were synthesized by combing chain walking ethylene polymerization in the presence of 4-vinylbenzyl chloride catalyzed with Pd-α-diimine and click chemistry or atom transfer radical polymerization (ATRP). The self-assembly behavior in water, a selective solvent for PEO and PAA, and the micelle morphology of HBPE-b-PEO and HBPE-b-PAA were investigated by laser light scattering (LLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The resultant diblock copolymers can self-assemble into spherical vesicles as demonstrated by LLS and TEM, which become collapsed on mica surface during drying as showed by AFM.

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