POS1-0376
Organobse-Catalyzed Metal-Free Proton Transfer Anionic Polymerization Using C–H Bonds as Dormant Species
When and Where
Nov 30, -0001
12:00am - 12:00am
Presenter(s)
Mei Okano (Nagoya University)
Co-Author(s)
Abstract
Metal-free polymerization has attracted much attention as an environmentally friendly approach with potential applications in biomaterials and electronic materials. Recently, we developed proton transfer anionic polymerization (PTAP) of methacrylates using C–H bonds as dormant species, which proceeds via proton transfer between growing enolates and dormant C–H chain ends. In this polymerization, esters and nitriles with weakly acidic C–H bonds serve as initiators or chain-transfer agents (CTAs) in the presence of base catalysts to produce polymers with controlled molecular weights. Since the base acts catalytically, the amount of base required per polymer chain can be reduced. However, the base catalysts used for PTAP have been limited to metal bases.
In this study, we investigated metal-free PTAP of acrylic monomers using catalytic amounts of organobases, such as phosphazene derivatives. Anionic polymerization of tert-butyl methacrylate was examined using phosphazene tBu-P4 in the presence of 2-phenylpropionitrile as a CTA. The monomer was consumed quantitatively, and the number-average molecular weights (Mn) of the products were close to theoretical values assuming that one polymer chain is produced from one molecule of CTA. However, the molecular weight distribution was broad. To improve the controllability, 2,2-diphenylethanol was added as a reversible terminator. Although the polymerization became slower, the molecular weight distribution became narrower (Ð ~ 1.15). These results indicate that molecular weight control was achieved by combining 2-phenylpropionitrile and tBu-P4 in the presence of 2,2-diphenylethanol.
To further explore the versatility of this metal-free PTAP, various acrylic monomers including acrylates and acrylamides were polymerized. Additionally, the effects of the basicity and bulkiness of organobase catalysts, as well as additive structures, on the polymerization behavior were investigated.
In this study, we investigated metal-free PTAP of acrylic monomers using catalytic amounts of organobases, such as phosphazene derivatives. Anionic polymerization of tert-butyl methacrylate was examined using phosphazene tBu-P4 in the presence of 2-phenylpropionitrile as a CTA. The monomer was consumed quantitatively, and the number-average molecular weights (Mn) of the products were close to theoretical values assuming that one polymer chain is produced from one molecule of CTA. However, the molecular weight distribution was broad. To improve the controllability, 2,2-diphenylethanol was added as a reversible terminator. Although the polymerization became slower, the molecular weight distribution became narrower (Ð ~ 1.15). These results indicate that molecular weight control was achieved by combining 2-phenylpropionitrile and tBu-P4 in the presence of 2,2-diphenylethanol.
To further explore the versatility of this metal-free PTAP, various acrylic monomers including acrylates and acrylamides were polymerized. Additionally, the effects of the basicity and bulkiness of organobase catalysts, as well as additive structures, on the polymerization behavior were investigated.
