Inclusion Complexes of Photosensitizers with Cyclodextrins for Enhancing the Fabrication of Volume Grating.

A supramolecule photosensitizer (supra-photosensitizer) based on the host-guest complexation of cyclodextrins and a bis-chalcone dye (BDEA) was prepared. Methyl-ß-cyclodextrin (Me-ß-CD), with the highest inclusion rate, was confirmed as the best host among the four cyclodextrins. The host-guest properties of Me-ß-CD and BDEA were characterized by FTIR, XRD, 1H NMR, PLQY, SEM, Job's plot, Benesi-Hildebrand plot, and others. Compared to the conventional photosensitizers, the supra-photosensitizers showed higher fluorescence emission and longer fluorescence lifetime whether as a powder or distributed in a film. The improvement in fluorescence coincided with improvement in photoinitiation efficiency and was proven to enhance the generation of volume grating. It is expected that the supra-photosensitizer may open a new avenue for the design of high-performance photoinitiation systems.

Effect of Glycerol on an N-Vinylpyrrolidone-Based Photopolymer for Transmission Holography.

N-vinylpyrrolidone (NVP) has a large molecular structure, so it is difficult to diffuse during holographic recording, especially at low spatial frequencies. We used glycerol to promote the diffusion of NVP, and successfully improved the holographic performance of the photopolymer at low spatial frequencies. As the concentration of glycerol increases, the holographic performance first increases and then remains stable. The optimal concentration of glycerol is 0.21 mol/L. At this concentration, the maximum diffraction efficiency of the photopolymer is 84%, the refractive index modulation is 1.95 × 10-3, and the photosensitive sensitivity is 7.91 × 10-4 cm2/mJ. Compared with the control group, the maximum diffraction efficiency, maximum refractive index modulation and photosensitivity at low spatial frequencies (800 lp/mm) have increased by 11.19 times, 4.69 times and 1.71 times, respectively. Using the optimized photopolymer for transmission holographic recording and reproduction, we have obtained a clear and bright transmission hologram. The photopolymer modified with glycerol is expected to be applied to the fields of holography, diffractive optics, and so on.