Dual Polymerization Pathway for Polyolefin–polar Block Copolymer Synthesis

Date

2022-04-29

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Abstract

The incorporation of functional groups into polyolefins is known to overcome its poor surface properties and improve the compatibility, adhesion, and printability of the materials. In addition, copolymers with a blocky architecture comprise segregated polyolefins and polar polymer segments that are covalently bonded can efficiently promote phase boundary expansion and as a result, compatibility. However, the tremendous difference in chemical reactivity between ethylene/ olefins and activated vinyl monomers has caused technical difficulties in their copolymerization. This dissertation focuses on the mechanistic investigation and development of synthetic routes to polyolefinpolar block materials. Chapter 3 directs toward uncovering the mechanism responsible for the activity alteration from coordination-insertion polymerization to free radical polymerization of cationic diimine palladium complex to produce polyolefinpolyacrylic block copolymers. The mechanistic findings suggest that the bridging component was a Pd-macrochelate formed via a single insertion of an acrylate monomer into the growing Pd-polyolefin intermediate. The mechanistic insights also facilitate the preparation of various di- and triblock copolymers using different Pd diimine systems and monomer classes. The obtained materials were rigorously characterized via multiple analytical techniques such as thermal analysis, small-angle X-Ray scattering, dynamic light scattering, and transmission electron microscopy to reveal the segregation that occurred in bulk or selective solvents caused by the exotic nature of the block copolymers. Chapter 4 describes a technique to install an active ester unit onto polyolefin chain ends via the use of a pre-functionalized palladium chelate. The active ester terminated polyolefins can go under functional group exchange to produce polyolefin macroinitiator or macromediator for controlled polymerization methods. Diverging from the approach described in Chapter 4, this technique provides tandem living/controlled polymerizations that allow the preparation of well-defined block copolymers with expanded monomer scopes. Reversible addition-fragmentation chain transfer polymerization-induced self-assembly (RAFT-PISA) of acrylamide monomers from polyethylene was also accomplished to directly produce amphiphilic block copolymer vesicles.

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Keywords

Block copolymers, Olefin, Insertion, Radical polymerization

Citation

Portions of this document appear in: Dau, Huong, Anthony Keyes, Hatice E. Basbug Alhan, Estela Ordonez, Enkhjargal Tsogtgerel, Anthony P. Gies, Evelyn Auyeung et al. "Dual polymerization pathway for Polyolefin-Polar block copolymer synthesis via MILRad: mechanism and scope." Journal of the American Chemical Society 142, no. 51 (2020): 21469-21483.