Photonic Polyethylene from Self-Assembled Mesophases of Polydisperse Olefin Block Copolymers

Abstract

We have discovered a synthetic process capable of producing olefin block copolymers (OBCs) with controlled block length polydispersity. Certain compositions of these OBCs self-assemble in the melt to form ordered mesophases. The morphologies and dielectric contrast of the semicrystalline and amorphous blocks produce transparent films exhibiting a partial photonic band gap for frequencies in the visible spectrum. The domain spacings are not only much larger than expected for monodisperse block copolymers of similar molecular weight, but they also exceed the predictions of recent theories for polydisperse block copolymers. An extension to Strong Segregation Theory demonstrates that many molecules have a weak preference for segregation to the interface versus the center of a domain. Minor perturbations can then produce highly swollen but relatively stable domains.

Regulation of crystalline morphologies and mechanical properties of olefin multiblock copolymers by blending polymer with similar architecture of constituent blocks

“…It is synthesized by the Dow Chemical Company via chain shuttling technology, in which two catalysts with different octene-selectivity and chain shuttling agent allowing for changing between the two catalysts are indispensable. [25][26][27][28][29][30] Although the hard and soft blocks of OBC are distinct in comonomer content, they are comparatively short and can be partially miscible in the melt. On the other hand, the hard blocks are long enough to form chain-folded lamellar crystals with a relatively high melting temperature.…”

Rapid self-assembly of brush block copolymers to photonic crystals

“…To overcome the practical limitations to the domain sizes and refractive indices of typical BCPs, assembled nanostructures are often swollen with additives, including small molecules (4,6,19), inorganic nanoparticles (20), or other polymers (17) to achieve photonic bandgaps in the visible and NIR. Additionally, extreme annealing conditions have been used successfully to prepare PC films from BCPs (21). The complex annealing procedures and additives demanded by much of the work to date on polymer PCs represent a huge barrier to the practical implementation of BCPs as commercially viable optical elements.…”

Angle‐Independent Structural Color in Colloidal Amorphous Arrays

“…Photonic crystals, consisting of dielectric microstructures with a periodicity of roughly half the visible light wavelength, are strong candidates for such materials because they reveal brilliant structural colors based on a pseudo-or complete photonic band gap (PBG) by Bragg reflection of light. Colloidal crystals composed of submicron-sized spherical monodispersed particles [9][10][11][12] and microphase-separated block copolymers [13][14] generated by self-assembly approaches have been under intense study for the preparation of photonic crystals as full color pixels. The structural color from these photonic crystals can be varied using an external stimulus such as an electric field or optical irradiation, due to the change in the periodicity or refraction index, without the need for color filters or optical elements.…”