Leland Stanford Junior University

Joyce Hung

Robert M Waymouth

Raisa L Kravchenko

Jennifer Maciejewski Petoff

This invention relates to high melting polyolefin copolymers suitable as thermoplastic elastomers and catalysts and methods for their synthesis. These elastomeric olefin copolymers are characterized by a mole fraction of crystallizable component X from about 30 to about 99%; low glass transition temperatures, below &minus;20&deg; C., and typically below &minus;50&deg; C.; melting points above about 90&deg; C.; high molecular weights; a molecular weight distribution M /M </&equals;10; and a narrow composition distribution between chains of </&equals;15%. The novel copolymers of the invention range from reactor blends to multiblock copolymers that can be sequentially fractionated into fractions of differing crystallinities, which fractions nevertheless show compositions of comonomers which differ by less than 15% from the parent polymer (reactor product). The invention also relates to a process for producing such copolymers by utilizing an unbridged, substituted or unsubstituted cyclopentadienyl metallocene catalyst that is capable of interconverting between states with different copolymerization characteristics, which interconversion is controlled by selecting the substituents of the cyclopentadienyl ligands so that the rate of interconversion of the two states is within several orders of magnitude of the rate of formation of a single polymer chain. Where r >r the polymer can be characterized as multiblock; where r <r , the result is a polymer blend and where r / r is close to 1, the resulting polymer is a mixture of blend and multiblock. The metallocene catalysts of the invention are able to interconvert between more than two states, with embodiments of four states being shown in FIG.

High-melting polyolefin copolymer elastomers, catalysts and methods of synthesis

Metallocene catalysts having plural coordination geometries for synthesis of high melting polyolefin copolymers suitable as thermoplastic elastomers. The inventive catalysts comprise unbridged, substituted or unsubstituted cyclopentadienyl metallocene catalysts that are capable of inter-converting between states with different polymerization or copolymerization characteristics, which interconversion is controlled by selecting the substituents of the cyclopentadienyl ligands so that the rate of interconversion of the two states is within several orders of magnitude of the rate of formation of a single polymer chain. Where r >r the polymer can be characterized as multiblock; where r <r , the result is a polymer blend and where r /r is close to 1, the resulting polymer is a mixture of blend and multiblock. The inventive metallocene catalysts are able to interconvert between more than two states, with embodiments of four states being shown in FIG.

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Stanford, CA, United States of America

Joyce Hung