Angela Mohanty - Transition Metal-Catalyzed Functionalization of Polyolefins Containing C-C, C=C, and C-H Bonds

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      Publication Details (including relevant citation   information):

         

    Mohanty, A.D. and Bae, C., Transition Metal-Catalyzed Functionalization of Polyolefins Containing C–C, C=C, and C–H bonds, in Advances in Organometallic Chemistry, editor: Pedro J. Perez, Vol. 64, ADOMC, UK: Academic Press, 2015, pp. 1-39

      Abstract:

      Polyolefins are prepared from vinyl monomers via free radical,

      anionic, cationic, and metal-catalyzed coordination   polymerization processes.

      In this review article, we divide them into two classes: (i)   saturated

       

      polyolefins, such as polyethylene (PE) and polypropylene (PP)   and (ii) unsaturated polyolefins, such as polybutadiene   (PBD), polystyrene (PS),

      and styrene-based copolymers. Regardless of whether they are   saturated or

      unsaturated, polyolefins are the most widely used commodity   materials

      because they have robust physical and mechanical properties and   use inexpensive

      feedstocks. Because polyolefins are made of only nonpolar   covalent

      bonds—primarily C-C, C=C (for unsaturated polyolefins), and C-H—

      they lack good surface adhesion properties and are seldom used   with other

      organic and inorganic materials.1  This disadvantage has thus far limited

      broader applications of polyolefins. Certain polyolefins,   particularly unsaturated

      ones, can be obtained as copolymers (e.g., copolymers of   styrene).

      However, the range of vinyl monomers that readily undergo   polymerization

      and the diversity of functional groups that can be incorporated   are often limited.

      Additionally, the copolymerization approach often yields polymers

      with insufficient molecular weight that cannot be used   commercially.  The chemical modification of polyolefins via   selective and controlled

      functionalization offers an alternative approach for the   incorporation of

      polar functionality to inherently nonpolar materials and changing   their specific

      properties. Traditional chemical modifications use free radical   and electrophilic

      addition/substitution reactions for saturated and unsaturated

      polyolefins, respectively. However, those reactions, which   involve highly

      reactive intermediates (i.e., free radicals and carbocations),   are generally difficult

      to control and are therefore accompanied with undesired side   reactions

      such as polymer chain scission and cross-linking. Because the   physical properties

      of polymer materials depend heavily on molecular weight and the

      extent of polymer chain entanglement, any deleterious side   reactions that

      negatively affect the molecular weights of functionalized   polymers sacrifice

      physical properties and should be avoided.  During recent   decades, transition metal complexes have been central in

      the catalysis of many new and existing organic reactions. Some of   these complexes

      have been successfully adopted for polymer functionalization. In   this

      review article, we summarize the recent progress of polyolefin   functionalization

      catalyzed by transition metal complexes. The sections are   conveniently

      divided according to polyolefin structure. We discuss

      modifications of polyolefins containing (i) alkene CdH bonds   such as those

      in PBD, (ii) aromatic CdH bonds   such as those in PS, and (iii) saturated

      CdC and   CdH bonds   such as those in PE. A number of excellent review

      articles and books have extensively discussed the chemical   modifications of

      polymers including polyolefins.2–9  Thus, this review primarily emphasizes

      catalytic polymer functionalization processes developed since the   late 1990s.

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