Hu, Yunfeng published the artcileManipulating the Relative Rates of Reaction and Diffusion in a Holographic Photopolymer Based on Thiol-Ene Chemistry, Recommanded Product: Pentaerythritol tetra(3-mercaptopropionate), the main research area is thiol ene reaction rate diffusion holog photopolymer.
Properly balanced reaction and diffusion kinetics are crucial for achieving optimal performance in holog. photopolymers. However, a comprehensive study on the effect of reaction and diffusion on the performance of thiol-ene-based holog. photopolymers has not been performed previously. To determine the relationship between reaction and diffusion, the refractive index modulation (Δn) of holog. gratings recorded in a model thiol-ene photopolymer system was evaluated with controlling the rates of reaction and diffusion processes. By changing the mol. weight of the polymer binder, the diffusion rate was varied over orders of magnitudes with the highest Δn of 0.026 achieved at a mol. weight of 2.9 x 104 Da. Meanwhile, the haze was significantly reduced in binders of higher mol. weight Similarly, as the reaction rate was reduced in accordance with lowering the light intensity, the Δn reached a peak value of 0.023 at 7 mW/cm2 and was found to decrease at both higher (2500 lines/mm) and lower (1000 lines/mm) spatial frequencies. In particular, Δn approaching 0 was observed at a very low intensity (2 mW/cm2) and when the binder with a mol. weight as low as 0.5 x 104 Da was used. An analogous formulation incorporating a secondary thiol, which has slower reaction kinetics and a more stable thiyl radical relative to the primary thiol, exhibited a lower Δn , especially at higher spatial frequencies. Through one-step thiol-Michael addition, the functionality of a tetrathiol monomer was reduced to various extents to obtain a series of thiol-ene photopolymers with precise control over gel point conversions, among which the thiol with an average functionality of 3.5 realized the highest Δn of 0.028. An enhanced reactive binder with norbornene pendant groups was also synthesized, and holog. gratings recorded in it showed notably higher Δn at low light intensities compared to those recorded in non-reactive or less reactive binders.
Macromolecules (Washington, DC, United States) published new progress about Diffusion. 7575-23-7 belongs to class alcohols-buliding-blocks, name is Pentaerythritol tetra(3-mercaptopropionate), and the molecular formula is C17H28O8S4, Recommanded Product: Pentaerythritol tetra(3-mercaptopropionate).
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