Borane comonomers

One example is shown in Scheme 13, involving direct metallocene copolymerization of ot-olefin and borane comonomer that is completely stable with the... 

Scheme 3 Functionalization of polyolefin using reactive borane comonomer...

Run no. a-Olefin Borane comonomer (mol%) Reaction temperature / time (°C/min) Borane in copolymer (mol%) Molecular weight (g/mol)... 

Dong JY, Manias E, Chung TC (2002) Functionalized syndiotactic polystyrene polymers prepared by the combination of metallocene catalyst and Borane comonomer. Macromolecules 35 3439... 

Functionalization and Block/Graft Reactions of Syndiotactic Polystyrene Using Borane Comonomers and Chain Transfer Agents... 

Unlike molecules containing electron-rich heteroatoms, boron compounds do not poison Ziegler-Natta or metallocene polymerization catalysts. Borane-containing olefin comonomers are therefore well suited to produce olefin copolymers while retaining good catalyst activity. The resulting polymers are suitable for subsequent conversion into a variety of functional groups. In principle, two approaches are possible (1) hydroboration of the terminal double bond (formed by typical chain transfer processes) of a preformed polyolefin, and (2) direct copolymerization of propylene or a 1-alkene with an alkenyl borane (Scheme 11.4). 

A comonomer that contains a reactive group should exhibit three essential properties (1) good stability with metallocene catalyst, (2) good solubihty with the reaction media, and (3) facile interconversion of reactive group into functional (polar) groups, such as OH and NH2 groups, after polymerization [3, 34]. In previous years, we had identified three suitable reactive comonomers, i.e., borane monomer, p-methylstyrene (p-MS), and divinylbenzene (DVB), as illustrated in Scheme 1. In concert with the selected metallocene catalysts, the copolymerization reactions take place to form well-controlled reactive polyolefin copolymers with various reactive sites in the side chains. Subsequently, the incorporated reactive... 

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