Methods of constructing alkene-based copolymer polyolefins having reduced crystallinity
The invention is a novel family of polyolefins characterized by chain-walking defects of the type that add extra backbone carbons per monomer. These polyolefins display a large decrease in crystallinity relative to polyolefins known in the art. Specifically, the reduction in crystallinity is much greater than for earlier polypropylenes with a matched content of stereo or 1-alkene type defects. The claimed polyolefins can be an alkene-based copolymer. The defects in the polyolefin backbone are generated by a chain walking mechanism in which three or more carbons per monomer are added to the polymer backbone instead of two, as in conventional polymerization or copolymerization methods of alpha olefins. The novel polyolefins can be used in applications such as plastic wrapping, thin films, co-extrusion layers or molded parts in the absence of polymer blending or copolymerization. The cost of materials production can be reduced.
1. A method to reduce crystallinity of a crystalline polyolefin comprising the steps of:
introducing at least one regio defect characterized by isolated or successive (2,1) additions and enchainments due to chain-walking;
wherein the enchainment straightens the monomer in the polyolefin backbone, adds extra backbone carbons and produces short crystallizable sequences without the need to use a comonomer;
wherein the molecular weight of the polyolefin is between about 30,000 and 200,000 daltons;
wherein the total regio defect percentage ranges between 3.0 to 20.0 mol %; and
wherein the crystalline polyolefin is an alkene-based copolymer.
2. The method of claim 1 , wherein the regio defect consists of isolated (2,1) additions, successive (2,1) additions, isolated enchainments due to chain-walking, two or more successive chain-walking enchainments, successive chain-walking followed by a (2,1) enchainment, and alternating chain-walking and (1,2) additions.
3. A method for the manufacture of a crystalline polyolefin product with reduced crystallinity comprising the steps of:
introducing at least one regio defect characterized by isolated or successive (2,1) additions and enchainments due to chain-walking;
wherein the enchainment straightens the monomer in the polyolefin backbone, adds extra backbone carbons and produces short crystallizable sequences without the need to use a comonomer;
wherein the molecular weight of the polyolefin is between about 30,000 and 200,000 daltons;
wherein the total regio defect percentage ranges between 3.0 to 20.0 mol %; and
wherein the crystalline polyolefin is an alkene-based copolymer.
4. The polyolefin of claim 3 , wherein the crystalline polyolefin is isotactic.
5. The polyolefin of claim 3 , wherein the crystalline polyolefin is syndiotactic.
6. The polyolefin of claim 3 , wherein the polyolefin is characterized by a polydispersity between about 1.14 and 1.46.
7. The method of claim 3 , wherein the polyolefin product are plastic wrapping, films, fibers, molded parts, medical devices, co-extrusions layers and coatings.
8. The method of claim 3 , wherein the regio defect consists of isolated (2,1) additions, successive (2,1) additions, isolated enchainments due to chain-walking, two or more successive chain-walking enchainments, successive chain-walking followed by a (2,1) enchainment, and alternating chain-walking and (1,2) additions.