Organic photo-catalyst for controlled synthesis of poly(methyl methacrylate) using spirooxazine initiator

Photoinitiated metal-free controlled living radical polymerization of methyl methacrylates was investigated using the nuclear aromatic compound of pyrene. In the presence of photoredox catalysts and UV irradiation, spirooxazine initiator was used as initiator for polymerization of methyl methacrylate with good control over molecular weight in range of 10000 – 14000 g/mol and polydispersity below 1.5. Moreover, the obtained polymer also exhibited photochromic properties under UV irradiation both in solution and in solid state film. We are reliable believe that organic-based photoredox catalysts will enable new applications for controlled radical polymerizations in both small molecules and polymer chemistry.

Catalyst-free iodine-mediated living radical polymerization under irradiation over a wide visible-light spectral scope

Catalyst-free iodine-mediated photo-induced solution LRP of methyl methacrylates under LED light was successfully established over a wide range of irradiation wavelengths (390–630 nm).

Photon Conversion and Radiation Synergism in Eu/Tb Complexes Incorporated Poly Methyl Methacrylate

Green and red emissions in terbium and europium benzoic acids (TBA and EBA) incorporated poly methyl methacrylates (PMMA) are exhibited. Larger intensity parametersΩ2(11.13×10-20 cm2) andΩ4(13.15×10-20 cm2) ofEu3+indicate a high inversion asymmetrical and strong covalent environment around lanthanide (Ln) ions and maximum emission cross sectionσem-max(2.45×10-21 cm2) for the dominant transitionD50→F27ofEu3+reveals the effective photon conversion capacity in EBA incorporated PMMA. Color variation and fluorescence enhancement are validated to be originated from energy transfer and synergistic effect in TBA/EBA coincorporated PMMA system. The results indicate that Eu and Tb complexes incorporated PMMA with effective photon conversion hold great prospect in increment of lighting quality and enhancement of solar-cell efficiency employed in outer space.

Casting Materials and their Application in Research and Teaching

From a biological point of view, casting refers to filling of anatomical and/or pathological spaces with extraneous material that reproduces a three-dimensional replica of the space. Casting may be accompanied by additional procedures such as corrosion, in which the soft tissue is digested out, leaving a clean cast, or the material may be mixed with radiopaque substances to allow x-ray photography or micro computed topography (µCT) scanning. Alternatively, clearing of the surrounding soft tissue increases transparency and allows visualization of the casted cavities. Combination of casting with tissue fixation allows anatomical dissection and didactic surgical procedures on the tissue. Casting materials fall into three categories namely, aqueous substances (India ink, Prussian blue ink), pliable materials (gelatins, latex, and silicone rubber), or hard materials (methyl methacrylates, polyurethanes, polyesters, and epoxy resins). Casting has proved invaluable in both teaching and research and many phenomenal biological processes have been discovered through casting. The choice of a particular material depends inter alia on the targeted use and the intended subsequent investigative procedures, such as dissection, microscopy, or µCT. The casting material needs to be pliable where anatomical and surgical manipulations are intended, and capillary-passable for ultrastructural investigations.