A method of polymerizing olefins is disclosed. The method comprises contacting ethylene and at least one comonomer with a catalyst system to produce a polyolefin polymer that is multimodal. The catalyst system comprises a first catalyst that promotes polymerization of the ethylene into a low molecular weight (LMW) portion of the polyolefin polymer and a second catalyst that promotes polymerization of the ethylene into a high molecular weight (HMW) portion of the polyolefin polymer. The first catalyst and at least a portion of the second catalyst are co-supported to form a commonly-supported catalyst system and at least a portion of the second catalyst is added as a catalyst trim feed to the catalyst system.

Catalyst systems and methods for making and using the same are described. A method includes selecting a catalyst blend using a blend polydispersity index (bPDI) map. The polydispersity map is generated by generating a number of polymers for at least two catalysts. Each polymer is generated at a different hydrogen to ethylene ratio. At least one catalyst generates a higher molecular weight polymer and another catalyst generates a lower molecular weight polymer. A molecular weight for each polymer is measured. The relationship between the molecular weight of the polymers generated by each of the catalysts and the ratio of hydrogen to ethylene is determined. A family of bPDI curves for polymers that would be made using a number of ratios of a blend of the at least two catalysts for each of a number of ratios of hydrogen to ethylene. A ratio for the catalyst blend of the catalysts that generates a polymer having a bPDI that matches a polymer fabrication process is selected, and the product specific polyolefin is made using the catalyst blend.

Polymers, and systems and methods for making and using the same are described herein. A polymer includes ethylene and at least one alpha olefin having from 4 to 20 carbon atoms. The polymer has a melt index ratio (MIR) greater than about 40. The polymer also has a value for Mw1/Mw2 of at least about 2.0, wherein Mw1/Mw2 is a ratio of a weight average molecular weight (Mw) for a first half of a temperature rising elution (TREF) curve from a cross-fractionation (CFC) analysis to an Mw for a second half of the TREF curve. The polymer also has a value for Tw1Tw2 of less than about 15 C., wherein Tw1Tw2 is a difference of a weight average elution temperature (Tw) for the first half of the TREF curve to a Tw for the second half of the TREF curve.

Catalyst systems and methods for making and using the same. A method of polymerizing olefins to produce a polyolefin polymer with a multimodal composition distribution, includes contacting ethylene and a comonomer with a catalyst system. The catalyst system includes a first catalyst compound and a second catalyst compound that are co-supported to form a commonly supported catalyst system. The first catalyst compound includes a compound with the general formula (C.sub.5H.sub.aR.sup.1.sub.b)(C.sub.5H.sub.cR.sup.2.sub.d)HfX.sub.2. The second catalyst compound includes at least one of the following general formulas: In both catalyst systems, the R groups can be independently selected from any number of substituents, including, for example, H, a hydrocarbyl group, a substituted hydrocarbyl group, or a heteroatom group, among others.

Catalyst systems and methods for making and using the same. A method of methylating a catalyst composition while substantially normalizing the entiomeric distribution is provided. The method includes slurrying the organometallic compound in dimethoxyethane (DME), and adding a solution of RMgBr in DME, wherein R is a methyl group or a benzyl group, and wherein the RMgBr is greater than about 2.3 equivalents relative to the organometallic compound. After the addition of the RMgBr, the slurry is mixed for at least about four hours. An alkylated organometallic is isolated, wherein the methylated species has a meso/rac ratio that is between about 0.9 and about 1.2.

Disclosed herein are ethylene-based polymers having a melt index less than 50 g/10 min, a ratio of Mw/Mn from 4 to 20, a density from 0.90 to 0.945 g/cm.sup.3, and a substantially constant short chain branch distribution. These polymers can be produced using a dual catalyst system containing a boron bridged metallocene compound with a cyclopentadienyl group and an indenyl group, and a single atom bridged metallocene compound with a fluorenyl group.

Disclosed herein are catalyst compositions containing boron bridged, cyclopentadienyl-indenyl metallocene compounds with an alkenyl substituent. These catalyst compositions can be used for the polymerization of olefins. For example, ethylene homopolymers produced using these catalyst compositions can be characterized by a density less than 0.97 g/cm.sup.3 and a melt index greater than 50 g/10 min.

Disclosed herein are ethylene-based polymers having a melt index less than 50 g/10 min, a ratio of Mw/Mn from 4 to 20, a density from 0.90 to 0.945 g/cm.sup.3, and a substantially constant short chain branch distribution. These polymers can be produced using a dual catalyst system containing a boron bridged metallocene compound with a cyclopentadienyl group and an indenyl group, and a single atom bridged metallocene compound with a fluorenyl group.

A method of polymerizing olefins is disclosed. The method comprises contacting ethylene and at least one co-monomer with a catalyst system to produce a polyolefin polymer that is multimodal. The catalyst system comprises a first catalyst that promotes polymerization of the ethylene into a low molecular weight (LMW) portion of the polyolefin polymer and a second catalyst that promotes polymerization of the ethylene into a high molecular weight (HMW) portion of the polyolefin polymer. The first catalyst and at least a portion of the second catalyst are co-supported to form a commonly-supported catalyst system and at least a portion of the second catalyst is added as a catalyst trim feed to the catalyst system.

Disclosed herein are catalyst compositions containing boron bridged, bis-indenyl metallocene compounds with an alkenyl substituent. These catalyst compositions can be used for the polymerization of olefins. For example, ethylene copolymers produced using these catalyst compositions can be characterized by a density less than 0.92 g/cm.sup.3 and a melt index greater than 25 g/10 min.