Abstract: The non-close-packed photonic crystal gels (NCPPCGs) with the range of Bragg diffractive peaks from 700 nm to 800 nm were fabricated. The relation between the swelling-shrinking of NCPPCGs and the shifts of the Bragg diffractive peaks was studied by their dehydrating in air and immersing in ethanol solutions with different concentrations and buffers with different pHs. When they were dehydrated in air, the Bragg diffractive peaks of the NCPPCGs blue-shifted; when they were immersed in water, the Bragg diffractive peaks of the dehydrated NCPPCGs red-shifted to the original position rapidly. The volume of the NCPPCGs varied when they were immersed in ethanol solutions with different concentrations, and their Bragg diffractive peaks blue-shifted proportionally with the concentrations of ethanol. The hydrolyzed NCPPCGs were pH-sensitive, and their Bragg diffractive peaks red-shifted in the pH range from 2.2 to 9.6, but blue-shifted in the pH range from 9.6 to 10.6. The Bragg diffractive peak positions of the prepared NCPPCGs can cover the entire visible region of light.

Key words: NCPPCGs, Swelling-shrinking, Bragg diffractive peak