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Published August 29, 2012 | public
Journal Article

Synthesis of Isocyanate-Based Brush Block Copolymers and Their Rapid Self-Assembly to Infrared-Reflecting Photonic Crystals

Abstract

The synthesis of rigid-rod, helical isocyanate-based macromonomers was achieved through the polymerization of hexyl isocyanate and 4-phenylbutyl isocyanate, initiated by an exo-norbornene functionalized half-titanocene complex. Sequential ruthenium-mediated ring-opening metathesis polymerization of these macromonomers readily afforded well-defined brush block copolymers, with precisely tunable molecular weights ranging from high (1512 kDa) to ultrahigh (7119 kDa), while maintaining narrow molecular weight distributions (PDI = 1.08–1.39). The self-assembly of these brush block copolymers to solid thin-films and their photonic properties were investigated. Due to the rigid architecture of these novel polymeric materials, they rapidly self-assemble through simple controlled evaporation to photonic crystal materials that reflect light from the ultra-violet, through the visible, to the near-infrared. The wavelength of reflectance is linearly related to the brush block copolymer molecular weight, allowing for predictable tuning of the band gap through synthetic control of the polymer molecular weight. A combination of scanning electron microscopy and optical modeling was employed to explain the origin of reflectivity.

Additional Information

© 2012 American Chemical Society. Received: July 2, 2012. Published: August 14, 2012. This work was supported by the NSF (CHE-1048404). R.A.W. thanks the Resnick Institute for a graduate fellowship.

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023