Shear ordered diblock copolymers with tuneable optical propertiesElectronic supplementary information (ESI) available: Further optical measurements of the sheared layer along with the optical properties of the dried film. See DOI: 10.1039/c0cp01481hThis article was submitted as part of a special collection on scattering methods applied to soft matter, marking the 65th birthday of Professor Otto Glatter

A series of high molecular weight poly(styrene- b -isoprene) block copolymers with optical properties defined by composition in a non-selective solvent were studied using simultaneous ultra small angle X-ray scattering (USAXS) and optical spectrometry. A small magnitude shear produces ordered and oriented states in the copolymer solutions that persist for extended periods of time, and also have superior optical properties that are directly attributable to the mesoscopic block copolymer (BCP) morphology. We have demonstrated that the optical transmission of these materials can be tuned by the addition of low molecular weight poly(isoprene) and poly(styrene) to swell their respective domains within the diblock copolymer. The optical transmission peak for the diblocks could be tuned; from 380 nm-440 nm for the 670k diblock, 425 nm-540 nm for the 850k diblock and 541 nm-625 nm for the 1 million diblock by altering the solution concentration and composition. The full width at half maximum that can be achieved for the optical transmission peaks is as small as 15 nm at 473 nm with a Δ λ / λ of 0.03, highlighting the high quality ordering in these systems. Also a small shift in the transmission peak wavelength was observed across a wide angle of view (15 nm at 30°) suggesting that these materials could be used for large area narrow band optical filters. Simultaneous ultra small angle x-ray scattering (USAXS) and optical spectroscopy were used to link the structural and optical properties of tuneable partially photonic block copolymer solutions.