There are now many examples of linear di-, tri-, and even tetra-block polyolefins in the literature. In most cases these are made by living anionic or coordination polymerizations followed, if necessary, by hydrogenation. In contrast, examples of crystallizable comb or graft block polyolefins seem to be rare. These offer an opportunity to extend structure-property relationships with new block topologies. In this presentation we will share an esterification strategy for making comb block polyolefins. The approach is illustrated by acid catalyzed esterification of commercial high pressure ethylene acrylic acid copolymer (EAA; 11 wt% AA, melting peak 94 °C, high pressure product) with atactic polypropylenehydroxide (aPPOH; Mn 1, 3, and 7kDa) and isotactic polypropylenehydroxide (iPPOH; Mn 6, 12, and 24kDa) macromonomers. The arm length, arm crystallinity, and arm content have been varied to produce a wide range of products. These products have been characterized by DSC, DMTA, 1H NMR, WAXS, SAXS, AFM, TEM, small angle oscillatory shear (SAOS), and extensional rheology. As expected, the samples self-assemble into finely textured, disordered morphologies in the solid state and the melt. They exhibit striking strain hardening behavior attributed, in part, to a phenomenon we ascribe to “interfacial pinning” of the many graft junctions for each EAA chain.

Synthesis and characterization of new polyolefin comb blocks comprised of a poly(ethylene-co-acrylic acid) scaffold and polypropylene arms: Exploration of the impact of number, length, and crystallinity of the grafted arms on melt and solid state properties

255th National Meeting (2018)

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