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
- Eprint ID
- 33924
- Resolver ID
- CaltechAUTHORS:20120907-091822265
- NSF
- CHE-1048404
- Resnick Institute Graduate Fellowship
- Created
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2012-09-07Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Resnick Sustainability Institute