Process for making ethylene-based polymers using carbon-carbon free radical initiators

A process for making a composition comprising an ethylene-based polymer, the process comprising the steps of:

• (A) contacting under first polymerization conditions at least ethylene and at least one molecular catalyst to form a first ethylene-based polymer, the molecular catalyst is a metal complex of a polyvalent aryloxyether corresponding to Structure B:
• where M3 is Hf or Zr;
• Ar4 independently at each occurrence is a substituted C9-20 aryl group, wherein the substituents, independently at each occurrence, are selected from the group consisting of alkyl;
• cycloalkyl;
• and aryl groups;
• and halo-, trihydrocarbylsilyl- and halohydrocarbyl-substituted derivatives thereof, with the proviso that at least one substituent lacks co-planarity with the aryl group to which it is attached;
• T4 is a C2-20 alkylene, cycloalkylene or cycloalkenylene group, or an inertly substituted derivative thereof;
• R21 independently at each occurrence is hydrogen, halo, hydrocarbyl, trihydrocarbylsilyl, trihydrocarbylsilylhydrocarbyl, alkoxy or di(hydrocarbyl)amino group of up to 50 atoms not counting hydrogen;
• R3 independently at each occurrence is hydrogen, halo, hydrocarbyl, trihydrocarbylsilyl, trihydrocarbylsilylhydrocarbyl, alkoxy or amino of up to 50 atoms not counting hydrogen, or two R3 groups on the same arylene ring together or an R3 and an R21 group on the same or different arylene ring together form a divalent ligand group attached to the arylene group in two positions or join two different arylene rings together;
• and
• RD, independently at each occurrence is halo or a hydrocarbyl or trihydrocarbylsilyl group of up to 20 atoms not counting hydrogen, or 2 RD groups together are a hydrocarbylene, hydrocarbadiyl, diene, or poly(hydrocarbyl)silylene group, and
• (B) contacting under second polymerization conditions the first ethylene-based polymer of (A) with at least additional ethylene and a carbon-carbon free radical initiator of Structure I:
• wherein R1, R2, R3, R4, R5 and R6 are each, independently, hydrogen or a hydrocarbyl group and wherein, optionally, two or more R groups (R1, R2, R3, R4, R5 and R6) form a ring structure, with the proviso that at least one of R2 and R5, and at least one of R3 and R6 is a hydrocarbyl group of at least two carbon atoms, to form a polymer composition comprising a second ethylene-based polymer.