Efficient Creation and Morphological Analysis of ABC Triblock Terpolymer Libraries

Multiblock copolymers with increasingly complex block sequences—for
example, triblock terpolymers—offer unique opportunities to create
nanostructured materials, but this potential has been hindered by a vast
design space that complicates the exploration of structure–property
relationships. Here, we report a versatile and scalable strategy to
separate parent ABC and isomeric ACB triblock terpolymers into libraries
of fractionated samples spanning a wide range of compositions. Using a
combination of controlled polymerization and automated chromatography, the
synthesis and separation of less than 10 ABC and ACB parent materials gave
rise to over 100 purified triblock terpolymers. Separations follow
systematic and predictable trends in volume fraction resulting from an
adsorption-based mechanism where chains rich in non-polar blocks elute
first followed by more polar derivatives, yielding fractions with improved
purity in composition and molar-mass dispersity. As evidenced by small
angle X-ray scattering (SAXS), fractionation significantly enhances
long-range order compared to as-synthesized parent materials and allows
for the definitive identification of various nanoscale morphologies. This
user-friendly separation strategy significantly increases the availability
of well-defined ABC triblock terpolymer libraries to the polymer community
while also improving sample quality and accelerating discovery.