Improving brush polymer infrared one-dimensional photonic crystals via linear polymer additives.
Brush block copolymers (BBCPs) enable the rapid fabrication of self-assembled one-dimensional photonic crystals with photonic band gaps that are tunable in the UV-vis-IR, where the peak wavelength of reflection scales with the molecular weight of the BBCPs. Due to the difficulty in synthesizing very large BBCPs, the fidelity of the assembled lamellar nanostructures drastically erodes as the domains become large enough to reflect IR light, severely limiting their performance as optical filters. To overcome this challenge, short linear homopolymers are used to swell the arrays to ∼180% of the initial domain spacing, allowing for photonic band gaps up to ∼1410 nm without significant opacity in the visible, demonstrating improved ordering of the arrays. Additionally, blending BBCPs with random copolymers enables functional groups to be incorporated into the BBCP array without attaching them directly to the BBCPs. The addition of short linear polymers to the BBCP arrays thus offers a facile means of improving the self-assembly and optical properties of these materials, as well as adding a route to achieving films with greater functionality and tailorability, without the need to develop or optimize the processing conditions for each new brush polymer synthesized.
Arnold and Mabel Beckman Laboratories for Chemical Synthesis and ‡Thomas J. Watson Laboratories of Applied Physics, California Institute of Technology , Pasadena, California 91125, United States.
Robert J
RJ
Macfarlane
Bongkeun
B
Kim
Byeongdu
B
Lee
Raymond A
RA
Weitekamp
Christopher M
CM
Bates
Siu Fung
SF
Lee
Alice B
AB
Chang
Kris T
KT
Delaney
Glenn H
GH
Fredrickson
Harry A
HA
Atwater
Robert H
RH
Grubbs