Facile Synthesis of Hydroxyl‐Terminated Oligoethylenes

Abstract

The synthesis of terminal hydroxyl-functionalized oligoethylene is achieved in a two-step one-pot method. Aluminum long chain alkyls (Al-PE) were generated by a catalytic chain transfer reaction involving iron 2,6-bis(imino)pyridyl ligation catalysts and methyl aluminoxane (MAO) aluminum alkyl precursors. At a high catalyst/cocatalyst ratio (>5 000) and a low ethylene pressure (1 bar) the chain transfer to aluminum is the dominant termination step. Discharging oxygen or dry air into the post polymerization reaction mixture leads to aluminum alkoxides (Al-O-PE) and after hydrolysis to hydroxyl-functionalized polyethylene (PE-OH). The degree of oxy-functionalization (up to 88 AE 3%) increased with increasing oxygen pressure and temperature and was more efficient with aluminum alkyls with a lower molecular weight.

Towards degradable polyethylene: end-functionalised polyethylene (PE-X) and PE-I/LDPE blends from iron-catalysed chain growth of ZnEt2 with ethylene

“…End-functionalised PE-X can then be used for the preparation of diblock copolymers. 8,22,[36][37][38][39][40][41] Oxidative workup of the M-C bonds to generate PE-OH has been reported for aluminium, 21,23,42 magnesium, 43,44 and zinc alkyls. [36][37][38][39][40][41]45,46 The end-functionalisation of polyethylene using magnesium alkyls as the chain transfer agent in combination with a neodymium polymerisation catalyst [(C 5 Me 5 ) 2 NdCl 2 Li(OEt 2 ) 2 ], first reported by Mortreux, 24 has been extensively investigated by Boisson and D'Agosto and co-workers.…”

“…1). A range of transition metal catalysts can be used, whereby transfer agents are typically based on main group metals such as trialkyl aluminium, [12][13][14][15][16][17][18][19][20][21][22][23] dialkyl magnesium, [24][25][26][27] or dialkyl zinc reagents. 12,[28][29][30][31][32][33] A specific case where all metal alkyl chains are equally engaged in reversible coordinative chain transfer polymerisation is termed Catalysed Chain Growth (CCG).…”

“…(1)). A range of transition metal catalysts can be used, whereby transfer agents are typically based on main group metals such as trialkyl aluminium, [12][13][14][15][16][17][18][19][20][21][22][23] dialkyl magnesium, [24][25][26][27] or dialkyl zinc reagents. 12,[28][29][30][31][32][33]…”

iPP/PE Multiblock Copolymers for Plastic Blend Recycling Synthesized by Coordinative Chain Transfer Polymerization

“…Note that in ref , where copolymers having a PE backbone with i PP side chains were reported, the macromonomer or side chain synthesis was accomplished in a nonliving fashion. Coordinative chain transfer polymerization (CCTP) is an economic alternative to living polymerization since an inexpensive metal alkyl, such as triethylaluminum (AlEt 3 ), diethylzinc, or dialkylmagnesium, acts as an initiator, , and an added polymerization catalyst mediates the chain growths of these alkyl groups successively in the presence of monomers, such as ethylene − and propylene. − One expensive catalyst molecule now forms numerous macromolecules in a highly controlled fashionliving polymerization multiplied.…”

Efficient One-Pot Synthesis of End-Functionalized trans-Stereoregular Polydiene Macromonomers

“…By comparison, the more tedious postfunctionalization, which is part of a multistep chemistry transformation, requires a prior isolation of the polymer. Up to now, important breakthroughs in terms of end-functionalized polymers have been obtained with ethylene and α-olefins, thanks to the living character offered by coordinative chain transfer polymerization (CCTP). − On the other hand, the preparation of polydienes bearing polar end-groups can be obtained by anionic polymerization of conjugated dienes; however, this strategy is limited to non-stereoregular polymers. , As far as stereospecific polymerization of conjugated dienes is concerned, and apart from block copolymers issued from a sequenced feed of nonpolar monomer followed by addition of polar monomers, − the elaboration of stereoregular polydienes that are also quantitatively end-functionalized remains a challenge that, to date, has scarcely been attained. − Several pathways can a priori be envisioned to achieve this goal of preparing end-functionalized stereoregular polydienes (Scheme ). The simplest way is to insert (i) a small electrophilic molecule, after full conversion of the monomer, into the living metal catalyst–macromolecular chain bond.…”