Semi-Crystalline Thermoplastic Block Copolymers

A semi-crystalline, thermoplastic polyolefin block copolymer comprising:

• (A) a first polyolefin B block comprising an ethylene and/or alpha-olefin/1-butene copolymer or terpolymer;
• (B) a polyolefin A block comprising isotactic poly(1-butene) (iPB);
• and
• (C) a second polyolefin B block comprising an ethylene and/or alpha-olefin/1-butene copolymer or terpolymer;
• the B and A blocks bonded to one another to form the polymer in which the first and second polyolefin B blocks are joined to and separated by the polyolefin A block.

A process for making a semi-crystalline, thermoplastic polyolefin ABA block copolymer, the process comprising the steps of:

• (A) feeding 1-butene to a high pressure reactor under polymerization conditions to produce a first A block of isotactic poly(1-butene) (iPB);
• (B) adding ethylene and/or a second alpha-olefin to the reactor under copolymerization conditions to form a B block of a 1-butene/ethylene copolymer, a 1-butene/alpha-olefin copolymer, or a 1-butene/ethylene/alpha-olefin terpoylmer which is attached to the first A block to form an AB block copolymer;
• and
• (C) stopping the addition of ethylene and/or the second alpha-olefin, and continue feeding 1-butene to the reactor under polymerization conditions to form a second A block of iPB which is attached to the B block to form the ABA block copolymer.

A process for making the semi-crystalline, thermoplastic polyolefin BAB block copolymer, the process comprising the steps of:

• (A) feeding 1-butene and ethylene and/or a second alpha-olefin to a reactor under copolymerization conditions to form a first B block of 1-butene/ethylene copolymer, a 1-butene/alpha-olefin copolymer, or a 1-butene/ethylene/alpha-olefin terpolymer;
• (B) stopping the addition of ethylene and the second alpha-olefin, and continue feeding 1-butene to the reactor under polymerization conditions to form an A block of isotactic poly(1-butene) (iPB) which is attached to the A block to form a BA block copolymer;
• and
• (C) restarting the addition of ethylene and/or a second alpha-olefin to the reactor under copolymerization conditions to form a second B block of a 1-butene/ethylene, a 1-butene/alpha-olefin copolymer, or a 1-butene/ethylene/alpha-olefin terpolymer which is attached to the A block to form the BAB block copolymer.