This invention relates to a method comprising combining an alkylidyne catalyst compound and a terminal alkyne to form a ring polymer. The terminal alkyne has the formula RC.sub.2H, wherein R is H, an alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group having from 3 to 20 carbon atoms, an aromatic group having from 6 to 20 carbon atoms, an alkenyl group having from 2 to 20 carbon atoms, or an alkynyl group having from 2 to 20 carbon atoms. The alkylidyne catalyst compound has the formula (R.sup.1)(R.sup.2)(R.sup.3) MCR.sup.4, where M is tungsten or molybdenum, R.sup.1, R.sup.2, and R.sup.3 is alkoxide, halide, oxide, nitride, or sulfide, and R.sup.4 is H, an aliphatic group having from 1 to 20 carbons, an aromatic group having from 1 to 20 carbons, or a heteroaryl group having from 1 to 20 carbons, wherein the heteroatom is nitrogen, oxygen, boron, or sulfur.

This invention relates to a method comprising combining an alkylidyne catalyst compound and a terminal alkyne to form a ring polymer. The terminal alkyne has the formula RC.sub.2H, wherein R is H, an alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group having from 3 to 20 carbon atoms, an aromatic group having from 6 to 20 carbon atoms, an alkenyl group having from 2 to 20 carbon atoms, or an alkynyl group having from 2 to 20 carbon atoms. The alkylidyne catalyst compound has the formula (R.sup.1)(R.sup.2)(R.sup.3) MCR.sup.4, where M is tungsten or molybdenum, R.sup.1, R.sup.2, and R.sup.3 is alkoxide, halide, oxide, nitride, or sulfide, and R.sup.4 is H, an aliphatic group having from 1 to 20 carbons, an aromatic group having from 1 to 20 carbons, or a heteroaryl group having from 1 to 20 carbons, wherein the heteroatom is nitrogen, oxygen, boron, or sulfur.

Processes for producing an activated chromium catalyst are disclosed, and these processes comprise contacting a supported chromium catalyst with a gas stream containing from 25-60 vol % oxygen at a peak activation temperature of 550-900° C. to produce the activated chromium catalyst. The linear velocity of the gas stream is 0.18-0.4 ft/sec, and the oxygen linear velocity of the gas stream is 0.05-0.15 ft/sec. The resultant activated chromium catalyst and an optional co-catalyst can be contacted with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

Processes for producing an activated chromium catalyst are disclosed, and these processes comprise contacting a supported chromium catalyst with a gas stream containing from 25-60 vol % oxygen at a peak activation temperature of 550-900° C. to produce the activated chromium catalyst. The linear velocity of the gas stream is 0.18-0.4 ft/sec, and the oxygen linear velocity of the gas stream is 0.05-0.15 ft/sec. The resultant activated chromium catalyst and an optional co-catalyst can be contacted with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

Shape, size and composition are nature's most fundamental design features, enabling highly complex functionalities. Despite recent advances, the independent control of shape, size and chemistry of macromolecules remains a synthetic challenge. Herein reported is a scalable methodology to produce large well-defined macromolecules with programmable shape, size and chemistry that combines reactor engineering principles and controlled polymerizations. Specifically, bottlebrush polymers with conical, ellipsoidal and concave architectures are synthesized using two orthogonal polymerizations. The chemical versatility is highlighted by the synthesis of a compositional asymmetric cone. The strong agreement between predictions and experiments validate the precision that this methodology offers.

Shape, size and composition are nature's most fundamental design features, enabling highly complex functionalities. Despite recent advances, the independent control of shape, size and chemistry of macromolecules remains a synthetic challenge. Herein reported is a scalable methodology to produce large well-defined macromolecules with programmable shape, size and chemistry that combines reactor engineering principles and controlled polymerizations. Specifically, bottlebrush polymers with conical, ellipsoidal and concave architectures are synthesized using two orthogonal polymerizations. The chemical versatility is highlighted by the synthesis of a compositional asymmetric cone. The strong agreement between predictions and experiments validate the precision that this methodology offers.

Processes for producing an activated chromium catalyst are disclosed, and these processes comprise contacting a supported chromium catalyst with a gas stream containing from 25-60 vol % oxygen at a peak activation temperature of 550-900° C. to produce the activated chromium catalyst. The linear velocity of the gas stream is 0.18-0.4 ft/sec, and the oxygen linear velocity of the gas stream is 0.05-0.15 ft/sec. The resultant activated chromium catalyst and an optional co-catalyst can be contacted with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

A composition comprising a high molecular weight, chromium catalyzed ethylene copolymer (also referred to as a polyethylene resin), a nucleating agent and zinc oxide.

A composition comprising a high molecular weight, chromium catalyzed ethylene copolymer (also referred to as a polyethylene resin), a nucleating agent and zinc oxide.

Supported chromium catalysts with an average valence less than +6 and having a hydrocarbon-containing or halogenated hydrocarbon-containing ligand attached to at least one bonding site on the chromium are disclosed, as well as ethylene-based polymers with terminal alkane, aromatic, or halogenated hydrocarbon chain ends. Another ethylene polymer characterized by at least 2 wt. % of the polymer having a molecular weight greater than 1,000,000 g/mol and at least 1.5 wt. % of the polymer having a molecular weight less than 1000 g/mol is provided, as well as an ethylene homopolymer with at least 3.5 methyl short chain branches and less than 0.6 butyl short chain branches per 1000 total carbon atoms.