Study On Polymerization Of Polar Monomers Mediated By Novel Lewis Pairs

Lewis pairs polymerization is a new type of polymerization developed in recent years,which utilizes either a classical Lewis adduct(CLA)or a FLP in which the LA and LB work cooperatively to activate the monomer substrate and participate in chain initiation,as well as chain propagation and termination/transfer events.It has shown lots of advantages such as a wide range of Lewis acids and Lewis bases,highly active polymerization of polar monomers at room temperature to obtain high molecular weight polymers,good regioselectivity etc.But also accompanied by poor stereochemistry control.In this paper,it was studied that stereoselective polymerization of polar monomers mediated by Lewis pairs system by using the following two strategies: 1)Design of Lewis acid with double acid centers and its acid-base adduct to control stereoselectivity of the polymerization through intramolecular synergism;2)Increasing volume of the polymerized monomer and controlling insertion of the monomer by the polymer chain end.Three novel Lewis acids based on binaphthyl or naphthalene skeleton and its adducts with Ph3 P were synthesized directly.We have also investigated their polymerization activity towards naturally renewable ?MMBL monomer and silyl methacrylates.1)The binaphthalene diene and 2-vinylnaphthalene ligands were directly reacted with HB(C6F5)2 to give the corresponding binaphthyldiborane and naphthylborane compounds,which have characterized by multinuclear magnetic resonance(1H,19 F,13C NMR).2)The synthetic novel Lewis acids were further reacted with Ph3 P to obtain the corresponding Lewis acid-base adducts,which have characterized by multinuclear magnetic resonance(1H,19 F,31P,13 C NMR).3)We could highly polymerize naturally renewable ?MMBL monomer to obtain high molecular weight polymers by utilizing novel Lewis acids generated in situ by mixing Piers borane and binaphthalene diene and N-heterocyclic carbine or some organophosphines,but could not control stereochemistry of the resulting polymer and obtained atactic polymers.4)The synthetic three adducts have also shown high polymerization activity for ?MMBL,and the activity difference of three adducts was higher with the decrease of catalyst concentration.Moreover,the resulting polymers have a high Tg and exhibit good thermal stability.5)Four silyl methacrylates monomers with varying silyl group bulkiness were synthesized,while TMSMA and TTMSSMA could be polymerized by Lewis pairs,and the corresponding PMMA converted from the resulting poly(silyl methacrylates)were considered syndiotactic-rich and isotactic respectively.