Optically transparent and high molecular weight polyolefin block copolymers toward self-assembled photonic band gap materials

Block copolymers based on readily available olefins have been synthesized to construct self-assembled one-dimensional (1-D) photonic crystals. Using living olefin polymerization via a bis(phenoxyimine)-titanium dichloride/MAO catalyst system, optically transparent and high molecular weight polyolefin block copolymers have been prepared with a narrow molecular weight distribution. The resulting copolymers exhibited a partial 1-D photonic band gap with an excellent optical transparency. Random copolymerization of olefin monomers provided a route to tune the refractive index of each block as well as to suppress the crystallinity for optical transparency. Ternary blending of diblock copolymer with homopolymers further afforded a pathway to control the wavelength of the peak reflectivity of the polyolefin-based photonic structures.