Substituted silanes as chain transfer agents for polyolefin production

A method of making an olefin-based polymer by free-radical polymerization in a reactor system, the method comprising:

• initiating a free-radical polymerization of an olefin-based monomer in the reactor system;
• propagating growth of the olefin-based polymer during continued free-radical polymerization of the olefin-based monomer;
• and
• adding to the reactor system a chain transfer agent that terminates the growth of the olefin-based polymer;
• wherein the reactor system comprises at least one tubular reactor;
• and
• wherein the chain transfer agent comprises a silane of formula (1):
• where
• R1, R2, R3, and R4 are independently selected from a hydrogen atom, a (C1-C40)hydrocarbyl, —N(R5)2, —Si(R5)3, —OSi(R5)3, —OR5, and —R6—Si(R5)3;
• each R5 is independently selected from a hydrogen atom and a (C1-C40) hydrocarbyl;
• each R6 is (C1-C40)hydrocarbylene;
• and
• optionally, any two of R1, R2, R3, and R4, or any two R5 bonded to the same nitrogen atom, or any two R5 bonded to the same silicon atom, are connected to form a ring having from 3 to 50 atoms in the ring, excluding any hydrogen atoms.

A method of making an olefin-based polymer by free-radical polymerization in a reactor system, the method comprising:

• initiating a free-radical polymerization of an olefin-based monomer in the reactor system;
• propagating growth of the olefin-based polymer during continued free-radical polymerization of the olefin-based monomer, wherein the reactor system comprises a pressure of greater than or equal to 100 MPa during the propagating the growth of the olefin-based polymer;
• and
• adding to the reactor system a chain transfer agent that terminates the growth of the olefin-based polymer;
• wherein the chain transfer agent comprises a silane of formula (1):
• where
• R1, R2, R3, and R4 are independently selected from a hydrogen atom, a (C1-C40)hydrocarbyl, —N(R5)2, —Si(R5)3, —OSi(R5)3, —OR5, and —R6—Si(R5)3;
• each R5 is independently selected from a hydrogen atom and a (C1-C40) hydrocarbyl;
• each R6 is (C1-C40)hydrocarbylene;
• and
• optionally, any two of R1, R2, R3, and R4, or any two R5 bonded to the same nitrogen atom, or any two R5 bonded to the same silicon atom, are connected to form a ring having from 3 to 50 atoms in the ring, excluding any hydrogen atoms.