Preparation and application of visible light LED sensitive photobase generator system
In response to the current problem of short absorption wavelength of photobase generator,which was difficult to match with commonly used visible light LED sources,based on the photosensitization mechanism,in this paper,a non-ionic photobase generator(PL-DBN)was synthesized by reducing amidine photobase generator,and its structure was characterized.It was compounded with photosensitizers(CQ,COU and ITX),three kinds of visible light sensitive photobase generator systems(PL-DBN/CQ,PL-DBN/COU and PL-DBN/ITX)were prepared,and their photophysical and photochemical behaviors were systematically investigated.The research results showed that,(1)The nuclear magnetic hydrogen spectrum indicated that the target product PL-DBN was successfully prepared.(2)By studying the light absorption properties of three kinds of photosensitizers,it was decided to select photosensitizers(CQ,COU and ITX)with different absorption ranges to be compounded with PL-DBN,respectively.(3)The efficiency of photolysis of different photosensitizers under 405 nm light source was investigated through steady-state photolysis experiments.Among them,PL-DBN/ITX showed a faster photolysis rate under 405 nm LED light source irradiation,making it more suitable for use in composite photobase generator systems.(4)Through the changes in UV-visible absorption spectra,it was found that the alkaline substances produced by the photolysis of the photobase generator system underwent acid-base neutralization reaction with phenol red,proving that PL-DBN could undergo photo induced alkali production reaction under 405 nm light source irradiation.(5)The effect of irradiation time on the kinetics of thiol-epoxy polymerization was investigated by using differential scanning calorimetry and Fourier transform infrared spectroscopy.The initial curing temperature of the system could be reduced by 23℃after 10 minutes of irradiation,and the conversion rate of thiol and epoxy functional groups could slowly increase to over 95%during a short period of heating after 10 minutes of light irradiation.(6)The bonding strength of the thiol-epoxy system after photothermal dual curing was tested.The thiol-epoxy system catalyzed by photobase generator had dark curing characteristics and could be applied in delayed curing adhesive,which had certain potential for future applications.
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