Spiropyran-functionalized photochromic nylon webbings for long-term ultraviolet light sensing

Webbing structures are extensively employed in engineering systems as load-bearing components. In a field setting, webbings are frequently subject to extended ultraviolet (UV) light irradiation, which can affect their integrity and reduce their mechanical strength. Despite technological advancements in structural health monitoring, long-term UV sensing techniques for webbings remain under-developed. To fill this gap, we propose a photochromic nylon webbing that demonstrates color variation in response to extended UV exposure. The webbing offers a rich, yet controlled, color variation over multiple time scales that is conducive to UV sensing. A mathematical model grounded in photochemistry is developed to interpret experimental observations, unveiling the photochromic phenomenon as a multi-step, multi-timescale photochemical process involving several chemical species. The model captures the evolution of the coexisting species through a system of nonlinear, coupled ordinary differential equations, offering the basis for the inference of the webbing’s color. The proposed photochromic webbing and the photochemistry-based mathematical model could inform future designs of UV-sensitive structures that maintain sensitivity under weeks of continuous sunlight UV exposure.

[1]  Xuchuan Jiang,et al.  VO2-based composite films with exemplary thermochromic and photochromic performance , 2020 .

[2]  Yoosik Kim,et al.  Chemo- and biosensing applications of spiropyran and its derivatives - A review. , 2020, Analytica chimica acta.

[3]  Debra J. Carr,et al.  Tensile properties of military chin-strap webbing , 2014 .

[4]  Mohammad Ghane,et al.  The effect of UV degradation on toughness of nylon 66/polyester woven fabrics , 2013 .

[5]  J. Andréasson,et al.  Characterization of the Thermal and Photoinduced Reactions of Photochromic Spiropyrans in Aqueous Solution , 2013, The journal of physical chemistry. B.

[6]  J. Nunzi,et al.  Photochemical and thermal spiropyran (SP)-merocyanine (MC) interconversion: a dichotomy in dependence on viscosity. , 2012, Physical chemistry chemical physics : PCCP.

[7]  T. Darwish,et al.  CO2 triggering and controlling orthogonally multiresponsive photochromic systems. , 2010, Journal of the American Chemical Society.

[8]  P. Fumagalli,et al.  Switching of nonfunctionalized spiropyran thin films on single crystalline MgO(100) , 2007 .

[9]  N. Harada,et al.  Synthesis, absolute configuration, and enantiomeric enrichment of a cruciferous oxindole phytoalexin, (S)-(-)-spirobrassinin, and its oxazoline analog. , 2001, The Journal of organic chemistry.

[10]  V. Malatesta,et al.  The Chemistry of Photomerocyanines , 2000 .

[11]  Toshihiko Nagamura,et al.  Ultrafast wide range all-optical switch using complex refractive-index changes in a composite film of silver and polymer containing photochromic dye , 1998 .

[12]  A. Bose,et al.  Formation of molecular H- and J-stacks by the spiropyran-merocyanine transformation in a polymer matrix , 1987 .

[13]  F. Shvartsman,et al.  Intramolecular interactions in photochromic spiropyran-merocyanine polymers , 1984 .

[14]  D. F. Swinehart,et al.  The Beer-Lambert Law , 1962 .

[15]  C. E. Dalgliesh,et al.  Beta-3-oxindolylalanine (hydroxytryptophan). 2. Spectroscopic and chromatographic properties. , 1951, The Biochemical journal.

[16]  K. Arai,et al.  Preparation of photochromic spiropyrans linked to methyl cellulose and photoregulation of their properties , 1996 .