(338x) Tailoring Comb-Branched Polyolefin Thermoplastic Elastomers Via Tandem Catalysis System.

Polyolefin thermoplastic elastomer (TPE-O) is a high-performance polyolefin composed of plastic and rubber phases. However, it remains elusive to accurately tailor the chain structure of TPE-O via a simple process to expand the operating temperature range and regulate the mechanical properties. Herein, we synthesized a novel comb-branched ethylene/propylene copolymer (CPOE) via solution polymerization in a tandem catalysis system consisting of rac-(dimethylsilylene)bis(2-methyl-4-phenylindenyl)-zirconium dichloride and (N-tert-butylamido) (tetramethylcyclopentadienyl)-titanium dichloride. The designed CPOE was composed of crystalline polypropylene side chains grafted onto an amorphous ethylene/propylene random copolymer backbone. By tailoring the number (0-11 branches /1000C) and length (Mn = 3-10 kDa) of side chains, the properties of CPOEs can be regulated flexibly. The CPOEs present high mechanical performances with tensile strength up to 10 MPa and elongation at break up to 1000%. The resulting CPOEs also possess high melting temperatures (>140 °C) and low glass transition temperatures (<−60 °C) at the same time. In addition, CPOEs can play a role as a compatibilizer in PE/PP blends, which is expected to facilitate the recycling of waste plastics. Furtherly, replacement of side chains with atactic polypropylene macromonomers will hopefully replace the role of α-olefins in TPE-Os. Our approach of synthesizing CPOEs thus promises the development of new high-performance elastomers.