Novel fluorescence method for cure monitoring of hydrosilation‐curable silicones

Abstract

This study aimed to evaluate a reactive fluorescent probe, 9,10-bis-(phenylethynyl) anthracene (BPEA), for cure monitoring of hydrosilation-curable silicones. The hydrosilation-curable silicones consisted of a vinyl-terminated polydimethylsiloxane prepolymer, a methylhydrosiloxane-dimethylsiloxane copolymer, and an inhibitor, 1,3-divinyltetramethyldisiloxane. The hydrosilation reaction was catalyzed with the solution of a platinum catalyst in the prepolymer. The catalyst solution also contained a trace amount of the reactive fluorescent probe. Three hydrosilation-curable silicones, with the prepolymer of varying molar mass, were investigated. Each of the hydrosilation-curable silicones was mixed with the catalyst solution at the mass ratio of 1 : 1 to initiate the cure. During the cure of each mixture at 22 C, the elastic modulus of the mixture and the fluorescence spectrum of the probe at the excitation wavelength of 360 nm were measured. Initially, the elastic modulus changed slowly, but then increased rapidly as a result of the increase in molar mass. The elastic modulus leveled off and reached a plateau value at the setting time. The ratio of the fluorescence intensities at 422 and 466 nm increased steadily, and then leveled off and reached a plateau value at the setting time, in agreement with the setting time determined from the change in elastic modulus. The reactive fluorescent probe, BPEA, can therefore be used for nondestructive fluorescence monitoring of hydrosilation-curable silicones.

Influence of surface treatment on the fluorescence of composite resins subjected to in situ bleaching

“…Fluorescence readouts were taken at 22°C (L0—24 hours after the surface treatment and L1—24 hours after staining) according to Hotta et al To evaluate fluorescence a spectrofluorometer SPEX Fluorolog‐2 (Edison, New Jersey) was used. The excitation wavelength was 390 nm and the scan was performed at 400 to 650 nm.…”

“…The excitation wavelength was 390 nm and the scan was performed at 400 to 650 nm. To evaluate the results a fluorescence peak of 440 nm was used.…”

Cyclometalated Platinum(II) Complexes Simultaneously Catalyze the Cross-Linking of Polysiloxanes and Function as Luminophores

“…Owing to the simultaneous availability of organic groups and an inorganic backbone, silicone elastomers exhibit a broad range of useful (and often complementary) properties, such as high elasticity, film-forming ability, remarkable thermal and thermo-oxidative resistance, electrical insulation, and biocompatibility. − The development of luminescent silicones has enabled the design of materials with superior application potential that are highly sought for the development of LEDs and oxygen sensors , and are used in photonics, electronics, the control of silicone coating evenness, and curing processes based on the cross-linking of hydrosilylation-curable silicones . Emitting fillers or immobilized luminophores can modify the photophysical properties of silicone rubbers to impart glowing features.…”