Poly(acrylic acid)-block-(2-cinnamoyloxylethyl methacrylate)-block-poly(perfluorooctyl ethyl methacrylate), PAA-b-PCEMA-b-PFOEMA, forms cylindrical micelles at room temperature in a, a, a-trifluorotoluene and methanol over a wide range of solvent compositions, at which PAA is soluble and PCEMA and PFOEMA are insoluble.  Heating the micelles at 70 oC, which is above the smectic A to disorder transition temperature for the liquid crystalline PFOEMA block, the cylinders transform into vesicular micelles.  The vesicles are reverted within 1 h to cylinders after the sample is cooled to room temperature.  Heating the cylinders to 50 oC renders the cylinders flexibility and causes their cyclization into torroidal, triangular, and square micelles.  More interestingly, PAA-b-PCEMA-b-PFOEMA and PtBA-b-PCEMA-b-PFOEMA with PtBA denoting poly(tert-butyl acrylate) can be mixed during the vesicle to cylinder conversion to yield blocky cylinders, which are enriched by the two polymers at different sections.  These results demonstrate the diversity and inter-conversion of the micellar morphologies of this triblock copolymer and our control over its self-assembly behavior.

Morphological diversity, transition, and control of micelles of an ABC triblock copolymer containing a liquid-crystalline block

244th National Meeting (2012)

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