| TECHNOLOGY |
Procedure for making Poly(Ethylene) copolymers from a single readily available monomer: Ethylene The new method avoids the need to feed a 1-alkene (Alpha olefin) into the polymn process. In the tandem-catalyst approach, 1-alkenes are produced from ethylene & inserted into a growing polyethylene chain in ONE-POT reaction. Co-polymn of ethylene with 1-alkenes introduces short alkyl branches into the growing polyethylene chain in a controlled fashion. Used commercially to make LLDPE, branching can lead to a prodt that is more processible than an unbranched prodt by modifying a polymer's d., MP & other properties. But to make branched PE via this type of co-polymn, producers need to manage 2 supplies of monomers. To make branched PE from single feedstock, the group needed to design a catalyst system in which the comp could work together efficiently in single medium. The group reacted a organo-Ni complex with tris(pentafluoro phenyl)boron to form Ni-borane adduct At 0C & 1 atm of ethylene, the Ni-borane compd yields 1-butene exclusively. Raising T to 65C & 3 atm leads to increased ethylene conversion but loss of selectivity. With their Ni catalyst converting ethylene to 1-butene, the researchers then added commercial-type organo-Ti catalyst (modified to include borane functionality) to the reactor to copolymerize alkenes. The group reports that the catalyst combination produces branched PE in a controllable & predictable fashion & notes that extent of branching in prodt depends linearly on Ni/Ti ratio |
| UPDATE | 03.00 |
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