Solid-State Polymerization Reactions for Passive and Active Guided Wave Components

A thin colorless radiochromic diacetylene monomer sensor coated on a transparent polyester base undergoes solid-state polymerization via free radical mechanisms when irradiated with ultraviolet 266 nm wavelength, x- and gamma rays, and high-energy electron beam irradiation. The radiation-induced polymerization reaction leads to the formation of 1, I-trans additions as polyconjugations along the ladder-like polymer chains. As a result, the colorless, transparent films responds to ultraviolet and to ionizing radiation by turning deep-blue, with an absorption spectrum that exhibits two distinct absorptions bands (lambda(max), = 675 nm and 610 nm). Pulse radiolysis and flash photolysis techniques were used to measure the kinetics of the polymerizaton propagation reactions. The pulsed-electron-induced propagation of polymerization has an observed first-order rate constant of the order of 10(3) s(-1), followed by much slower blue-shift of the primary absorption band (lambda(max) = 675 nm --> 660 nm). The activation energy of the polymerization was found to be approximate to 50 kJ mol(-1). The fast kinetics of the UV-induced polymerization is faster by about one order of magnitude (k(obs) = 1.5 x 10(4) s(-1)). The film can be utilized for optoelectronics, remote sensing, and radiation dosimetry.