Synthesis of vinyl-terminated isotactic poly(propylene)

C1‐Symmetric Heterocyclic Zirconocenes as Catalysts for Propylene Polymerization, 2

“…[39] This observation is in line with earlier reports by Weng on the synthesis of allyl-terminated i-PP with racMe 2 Si(2-Me-4-PhInd) 2 ZrCl 2 /MAO in toluene at 75-120 8C and at low-propylene pressure. [40] Due to the presence of two active sites on the same metal center, both undergoing monomer insertion and chain release reactions at rates with likely different temperature dependences, the Arrhenius plots built from molecular weight data at different T p values should not in general be expected to give linear correlations. The ln(P n ) versus 1/T Arrhenius plots for data in the relatively narrow T p range 50-70 8C give, however, acceptably linear correlations, from which the approximate DDE rel { values for the overall activation energy for chain release [2] can be estimated:…”

Polyolefins with Long Chain Branches Made with Single‐Site Coordination Catalysts: A Review of Mathematical Modeling Techniques for Polymer Microstructure

“…Macromonomers can also be formed during propylene polymerization by b-methyl elimination. [6] The other transfer steps commonly associated with coordination polymerization, such as transfer to cocatalyst, hydrogen, or other small molecules, generate chains with saturated ends that cannot react to form LCBs. These chains are effectively dead from a polymerization point of view, while the macromonomers can be ''resuscitated'' via LCB-formation reactions.…”

Synthesis of Long-Chain Branched Propylene Polymers via Macromonomer Incorporation

“…Both were synthesized according to procedures reported in the literature. [15,17] The copolymerization of propylene with macromonomers was conducted in a 2-L autoclave reactor in either batch or semi-batch mode. Typically, a 2-L autoclave reactor was charged with macromonomer (5-20 g), and the macromonomer was dried in the reactor at 110 8C under N 2 atmosphere.…”

“…The macromonomers had 60-70% chain-end vinyl unsaturation. [15] Besides batch reactions, polymerizations were also carried out in a semi-batch reactor where propylene was added slowly (2.5 mL/min). The low concentration of propylene in a semi-batch reactor would enhance the incorporation of PP macromonomer.…”

“…[14] Previously, we reported the synthesis of isotactic PP with predominantly vinyl-terminated chain ends and in size ranges above M e . [15] In this work, they are used as macromonomers to make long-chain branched PPs with known LCB length. Since the composition, the molecular weight, and the amount of macromonomer used may be controlled, the structural features of the resulting LCB model polymers may be defined by polymerization statistics.…”