Nanogel Nanosecond Photonic Crystal Optical Switching

• Published in: Journal of the American Chemical Society 2004-02, Vol.126 (5), p.1493-1496
• Main Authors: Reese, Chad E, Mikhonin, Alexander V, Kamenjicki, Marta, Tikhonov, Alexander, Asher, Sanford A
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electrical, magnetic and optical properties; Exact sciences and technology; Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Organic polymers; Physicochemistry of polymers; Physics; Properties and characterization
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja037118a

We developed a robust nanosecond photonic crystal switching material by using poly(N-isopropylacrylamide) (PNIPAM) nanogel colloidal particles that self-assemble into crystalline colloidal arrays (CCAs). The CCA was polymerized into a loose-knit hydrogel which permits the individual embedded nanogel PNIPAM particles to coherently and synchronously undergo their thermally induced volume phase transitions. A laser T-jump from 30 to 35 °C actuates the nanogel particle shrinkage; the resulting increased diffraction decreases light transmission within 900 ns. Additional transmission decreases occur with characteristic times of 19 and 130 ns. Individual NIPAM sphere volume switching occurs in the ∼100 ns time regime. These nanogel nanosecond phenomena may be useful in the design of fast photonic crystal switches and optical limiting materials. Smaller nanogels will show even faster volume phase transitions.