**4. Applications and niche markets of specialty polyolefins**

Until 30 years ago, the physical properties of polyethylene such as density and melt index values as well as chemical characteristics i.e., inherent hydrophobicity were limited. However, the innovative single-site catalysts have removed the barriers and polyethylene products with lower densities became available. Generally, such polyethylene grades are ethylene-α-olefin copolymers where α-olefin content exceeds 40 wt% in some cases and results in elastomeric properties. In addition, ethylene-cyclic olefin (e.g., norbornene or cyclopentadiene) copolymers, also known as specialty polyolefins, extend the polyolefin properties boundaries and the alkenes' value chain.

On the other side, according to their non-polar nature, commercial polyolefins suffer from a lack of adhesion, printability, wettability, reactivity, compatibility, and miscibility. Hence, applying such an intrinsically hydrophobic polymer as an adhesive, coating, paint, primer, or binder is restricted. Also, the poor interaction of polyolefins with other materials like paints, pigments, glass fibers, clay, carbon black, metals, and the vast majority of polymers limited their applications in blends and composites [5].

However, incorporating functional groups on the polyolefin chain, even at the chain-ends, branch-ends or backbone, leads to the enhancement of polyolefins' adhesion and binding properties, which opens up exciting industrial application fields. So far, functional polyolefins' applications comprised of binders in bookbinding, glue in adhesives, printing inks, tie-layer in multilayer sheets or films, and compatibilizer in blends of polar and non-polar polymers. Interestingly, they may open up new possibilities for application in film capacitors with superior energy density, proton exchange membranes for fuel cells and super-absorbents suitable for the oil spills (without any water) absorption [12].

Herein, commercially available specialty polyolefins, including functional olefin copolymers as valuable extenders of the alkenes' value chain, are comprehensively reviewed. Some of the structures of value-added polyolefins presented in this chapter are shown in **Figure 4**.

#### **Figure 4.**

*The chemical structure of some of the specialty polyolefins with niche applications which will be discussed in this chapter.*
