A series of titanium and zirconium complexes with ligands based on di-isopropyl phosphorus-phenylamine and their derivatives were synthesized and characterized. These catalysts were utilized to catalyze the copolymerization of ethylene with N-acetyl-O-(dec-9-enyl)-L-tyrosine ethyl ester with high catalytic activity of 6.63 × 10 4 g P (mol Ti)after activation by methylaluminoxane (MAO). The effects of ligand structure, metal atoms (Ti, Zr) and polymerization conditions were investigated in detail. The obtained polymers were characterized by 13 C-NMR, DSC, FT-IR, and GPC. The results showed that the obtained copolymer had a high comonomer incorporation rate of 2.56 mol % within the copolymer chain. The melting temperature of the copolymer was up to 138.9 °C, higher than that of the obtained homopolyethylene.
OPEN ACCESSCatalysts 2015, 5 1832
A series of N-acetyl-O-(ω-alkenyl)-L-tyrosine ethyl esters were synthesized by the reaction of vinyl bromides (4-bromo-1-butene, 6-bromo-1-hexene, 8-bromo-1-octene and 10-bromo-1-decene) with N-acetyl-L-tyrosine ethyl ester. 1 H NMR, elemental analysis, FT-IR, and mass spectra were performed for these N-acetyl-O-(ω-alkenyl)-L-tyrosine ethyl esters. The novel titanium complex can catalyze the copolymerization of ethylene and N-acetyl-O-(ω-alkenyl)-L-tyrosine ethyl esters efficiently and the highest catalytic activity was up to 6.86ˆ10 4 gP¨(molTi)´1¨h´1. The structures and properties of the obtained copolymers were characterized by FT-IR, ( 1 H) 13 C NMR, GPC, DSC, and water contact angle. The results indicated that the obtained copolymers had a uniformly high average molecular weight of 2.85ˆ10 5 g¨mol´1 and a high incorporation ratio of N-acetyl-O-(but-3-enyl)-L-tyrosine ethyl ester of 2.65 mol % within the copolymer chain. The units of the comonomer were isolated within the copolymer chains. The insertion of the polar comonomer into a copolymer chain can effectively improve the hydrophilicity of a copolymer.
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