Synthesis of multiblock ethylene/long-chain α-olefin copolymer via chain walking polymerization using thermostable α-diimine nickel catalyst

Symmetric and Asymmetric Binuclear α-Diimine Nickel(II) Complexes for Ethylene Polymerization

 A series of symmetric and asymmetric binuclear α-diimine nickel(II) complexes toward ethylene polymerization were successfully synthesized and characterized by 1HNMR. All the catalysts were typically activated with MAO and displayed good activity at room temperature under 1atm ethylene pressure. The symmetric catalyst containing isopropyl on l...

Catalytic production of olefin block copolymers via chain shuttling polymerization.

We report a catalytic system that produces olefin block copolymers with alternating semicrystalline and amorphous segments, achieved by varying the ratio of alpha-olefin to ethylene in the two types of blocks. The system uses a chain shuttling agent to transfer growing chains between two distinct catalysts with different monomer selectivities in a single polymerization reactor. The block copoly...

Synthesis and application of binuclear α-diimine nickel/palladium catalysts with a conjugated backbone.

A series of binuclear nickel/palladium catalysts C4-C7 with conjugated α-diimine ligands were designed, prepared and fully characterized. The binuclear nickel complexes C6 and C7 were activated by modified methylalumoxanes (MMAO) to generate highly active ethylene polymerization catalysts with activities up to 1050 kg [mol (Ni) h](-1). The activity of C7 is twice that of the mononuclear analogu...

Thermostable α-amylase from Lignocellulosic Residues Using Bacillus amyloliquefaciens

Synthesis of chitin and chitosan stereoisomers by thermostable α-glucan phosphorylase-catalyzed enzymatic polymerization of α-D-glucosamine 1-phosphate.

The relationship between two aminopolysaccharide stereoisomers, namely α-(1→4)- and β-(1→4)-linked (N-acetyl)-D-glucosamine polymers, is of significant interest within the field of polysaccharide science, as they correspond to amino analogs of the representative abundant natural polysaccharides, viz. amylose and cellulose. While the latter glucosamine polymer is the basis of well-known natural ...