The Effect of UV Irradiation on the Transmittance Bands of Polystyrene-block-2-vinylpyrimidine

• Published in: Molecular crystals and liquid crystals (Philadelphia, Pa. : 2003) Vol. 539; no. 1; pp. 96/[436] - 101/[441]
• Main Authors: Lee, Sung Woo, Shin, Jeesun, Shin, Jhoseph, Shim, Christine, Shin, Dong Myung
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 31-05-2011
• Subjects: Bands; Block copolymer; Blocking; Ethyl alcohol; Film thickness; Irradiation; photonic crystals; poly(styrene-block-2-pyridine); Pyridines; Self assembly; Transmittance; UV irradiation
• ISSN: 1542-1406; 1563-5287
• DOI: 10.1080/15421406.2011.566068

Block copolymers have been investigated for fabricating functional nanomaterials due to their properties of self-assembly. We prepared polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) lamellar films which is hydrophobic block-hydrophilic polyelectrolyte block polymer have 57 kg/mol-b-57 kg/mol. The lamellar stacks are obtained by exposing the spin coated film under chloroform. The P2VP blocks were then quaternized and crosslinked to various extents using 5 wt% of iodomethane.
PS-b-P2VP films showed excellent photonic bands at 630 nm after swelling with ethanol and 661 nm with water after treated with Calcium Carbonate. We observed significant band shift from 663 nm (deep red) to 531 nm (green) during UV-irradiation for 40 seconds.
The phase separation process of BCP was very sensitive to the film thickness. The quarternized films with thickness varied from 0.43 µm (446 nm transmittance minimum) to 0.25 μm (478 nm transmittance minimum). This study shows that the total film thickness and UV irradiation effectively change the transmittance band by affecting the thickness of layers consisting of PS-b-P2VP photonic crystals.