Segmented multiblock polyolefin compatibilizers from non-living metathesis chain-shuffling.

Area of Science:

• Polymer Science
• Materials Science
• Chemical Engineering

Background:

• Mixed plastics present recycling challenges due to poor compatibility.
• Block copolymers are effective compatibilizers for immiscible polymer blends.
• Developing efficient compatibilizers for abundant plastics like PE and PP is crucial for sustainable materials management.

Purpose of the Study:

• To synthesize and characterize novel semi-crystalline/semi-crystalline linear multiblock copolymers of LLDPE and PP.
• To evaluate the compatibilization and toughening effects of these multiblock copolymers on LLDPE/PP blends.
• To understand the reinforcement mechanisms contributing to improved mechanical properties.

Main Methods:

• Non-living shuffling polymerization to create multiblock copolymers.
• Characterization using NMR, DSC, X-ray scattering, and microscopy (TEM).
• Analysis of multiblock connectivity, crystallinity, morphology, and mechanical properties (tensile modulus).

Main Results:

• Successfully synthesized multiblock copolymers with up to 13 PE and PP blocks.
• Demonstrated significant compatibilization and toughening of LLDPE/PP blends, with enhanced tensile modulus.
• Observed minimal phase separation and imbibing of amorphous chains into the semi-crystalline block copolymer phase.

Conclusions:

• The synthesized multiblock copolymers effectively compatibilize and enhance the mechanical properties of mixed PE and PP.
• Reinforcement mechanisms include tie-chain, trapped entanglement, and co-crystallization.
• This work offers a pathway for designing advanced compatibilizers for toughening post-consumer plastic blends.