Shear alignment of ABC bottlebrush triblock terpolymers

Bottlebrush copolymers represent an appealing platform for self-assembly, as their extended backbone conformations couple with diminished entanglement density to enable access to 100 nm domains with relatively facile ordering kinetics. The addition of a third block creates a competition between the curvatures of two internal interfaces (A/B and B/C), leading to a variety of novel phases. Using ring-opening metathesis polymerization of well-defined macromonomers (polystyrene, poly(ethylene-alt-propylene), poly(ethylene oxide) and polylactide), we have explored the self-assembly of a large library of ABC triblock terpolymers. A common motif is cylinders of the C block in a B matrix interspersed between undulating layers of A, with the relative cylinder packing adopting various plane groups (e.g., c2mm, p2, p4mm). A new reciprocating shear device has been implemented for in-situ SAXS at the Advanced Photon Source. Results indicate that ABC bottlebrushes are highly susceptible to shear alignment, with a surprising sensitivity to applied frequency.