(790e) Digital Synthesis of Polyolefins With Controlled Structures By Living Coordination Polymerization

The digital manufacturing technology has been highly developed in machinery industry. Recently, the fast growth in the 3D printing technique proposed that is it possible to digital produce in chemical industry? As polyolefin products occupy more than half of world's polymer market, it is of great interest to apply digital production technology in polyolefin industry. Kinetic modeling, combined with living coordination polymerization technique, would greatly help us to digital produce polyolefin products with controlled structures, as illustrated in Figure 1.

In this work, living coordination copolymerization of ethylene with 1-octene was successfully performed at room temperature, using the fluorinated FI-Ti catalyst system, bis[N-(3-methylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] TiCl₂/dMAO. A kinetic model with good prediction was developed for the living copolymerization system. Ethylene/1-octene random copolymers with uniform intra-chain composition distribution were synthesized. DSC thermal fractionation revealed these living random copolymers had more homogeneous composition distribution than traditional metallocene-catalyzed random copolymers.

Polyolefin block copolymers with diblock or step-triblock structure were synthesized from semi-batch comonomer feeding policy. These block copolymers had the exact composition distribution and molecular weight as the model simulated. The block copolymers possessed high melting temperature of the hard block, together with low glass transition temperature of the soft block. DSC thermal fractionation revealed that the lamellar thickness of living diblock copolymer showed bimodal distribution and that of step-triblock copolymer showed trimodal distribution, different from the single modal distribution for OBC multiblock copolymers produced from chain shuttling polymerization.

This work demonstrated that the microstructure of polyolefins could be precisely manipulated by living coordination polymerization assisted by kinetic model design. Such design and control over chain microstructure allow us to tailor-make polyolefin materials.