Sevil Savaskan Yilmaz

Synthesis of a New Macroperoxy Initiator with Methyl Methacrylate and T-Butyl Peroxy Ester by Atom Transfer Radical Polymerization and Copolymerization with Conventional Vinyl Monomers

In this study, we present the synthesis of poly-MMA macroperoxy initiators obtained by the ATRP of MMA with bromo methyl benzyl t-butyl peroxy ester (t-BuBP) as an initiator, and CuX (X:Br or Cl)/2,2′-bipyridine (bpy) as a catalyst system at 0, 20, 30 and 40°C. The peroxygen groups do not decompose during the ATRP reaction, because low reaction temperatures used for the ATRP reaction are not enough to decompose them. The peroxygen groups of poly-PMMA macroperoxy initiators can lead them to react with a monomer by using appropriate reaction conditions to obtain the block or graft copolymers. For this purpose, poly-MMA macroperoxy initiators were used to synthesize poly(MMA-b-S) block copolymers with S and used for graft copolymerization of polybutadiene (PBd) and natural rubber (RSS-3) to obtain crosslinked poly(MMA-g-PBd) and poly(MMA-g-RSS-3) graft copolymers. Swelling ratio values of the crosslinked graft copolymers in CHCl3 were calculated. The characterizations of the polymers were achieved by FT-IR, 1H-NMR, GPC, DSC, SEM, and the fractional precipitation (γ) techniques. The reaction schemes were also performed using the HYPERCHEM 7.5 program. The mechanical properties of the products were investigated.

The quantum chemical investigation of molecular complexes formed with bromine molecule of adamantylideneadamantan and its derivatives: electronic and steric effects

Abstract The strain energies and the pyramidalization parameters of adamantylideneadamantan (AD), trans-(1-methyl-2-adamantyliden)-1-methyladamantan (DMAD) and trans-(1-tert-butyl-2-adamantyliden)-1-tert-butyladamantan (DBAD) molecules were calculated by MM2 and AMBER molecular mechanic methods. The strain energy and the pyramidalization degree of the molecule are increased by increasing the volume of R groups at the allylic position of the double bond. The electron structure of the molecules were investigated by PM3 semiempirical method. Molecular mechanic and PM3 methods, the results of which agree with the X-ray results, showed that the double bond of AD molecule has a planar structure. The molecular complexes (1:1 π-complexes) of the molecules formed with Br2 were investigated by PM3 method and it was seen that the stable configuration of them had the axial structure. The electronic and the steric factors affecting the structure and the stability of the molecular complexes were studied. It was found that DMAD⋯Br2 complex is more stable than AD⋯Br2 complex which was in accordance with the experimental results. It was determined that DBAD⋯Br2 complex containing the bulky tert-butyl group has the lowest stabilization energy among the investigated molecular complexes.