Precision Alkyl-Branched Polyolefins

For more than half a century studies on structure and morphology have been central to polyolefin research (Gedde and Mattozzi, 2004). Discoveries in this area have allowed for the 

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Recently, a new synthetic route (Figure 10.5) to symmetric alkyl branched dienes has been presented and utilized in the synthesis of a whole family of precision alkyl-branched polyolefins (Rojas et al, 2007). This general route, which can be used to create dienes with virtually any branch, involves only two steps with quantitative yields. The first step is the dialkylation of a primary nitrile using freshly prepared lithium diisopropylamide (LDA). Alkylation in this fashion affords a symmetric diene premonomer with the desired alkyl branch and a nitrile group on the central carbon. In the next step, this nitrile is removed by reductive elimination in the presence of potassium metal, HMPA, and r-butanol. 

Y.Y. Wei, R. Graf, J.C. Sworen, C.Y. Cheng, C.R. Bowers, K.B. Wagener, H.W. Spiess, Local and collective motions in precise polyolefins with alkyl branches a combination of H-2 and C-13 solid-state NMR spectroscopy, Angew. Chem. Int. Ed. Engl. 48 (2009) 4617-4620. 

Thermal behavior of precision polyolefins with increasing alkyl branch size... 

Increasing the Spacing Between Alkyl Branches in Precision Polyolefins... 

Rojas, G., Berda, E.B., and Wagener, K.B. (2008) Precision polyolefin structure modeling polyethylene containing alkyl branches. Polymer, 49,2985-2995. 

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