Samarium powder as catalyst for SET‐LRP of acrylonitrile in 1,1,1,3,3,3‐hexafluoro‐2‐propanol for control of molecular weight and tacticity

Abstract

Samarium powder was applied as a catalyst for single electron transfer‐living radical polymerization (SET‐LRP) of acrylonitrile (AN) in 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) with 2‐bromopropionitrile as initiator and N,N,N′,N′‐tetramethylethylenediamine as ligand. First‐order kinetics of polymerization with respect to the monomer concentration, linear increase of the molecular weight with monomer conversion, and the highly syndiotactic polyacrylonitrile (PAN) obtained indicate that the SET‐LRP of AN could simultaneously control molecular weight and tacticity of PAN. An increase in syndiotacticity of PAN obtained in HFIP was observed compared with that obtained by SET‐LRP in N,‐N‐dimethylformamide (DMF). The syndiotacticity markedly increased with the HFIP volume. The syndiotacticity of PAN prepared by SET‐LRP of AN using Sm powder as catalyst in DMF was higher than that prepared with Cu powder as catalyst. The increase in syndiotacticity of PAN with Sm content was more pronounced than the increase in its isotacticity. The block copolymer PAN‐b‐polymethyl methacrylate (52,310 molecular weight and 1.34 polydispersity) was successfully prepared. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Hexafluoroisopropanol as a highly versatile solvent

“…Single electron transfer-living radical polymerisation (SET-LRP) was reported by Percec and co-workers 94 and has significant benefits over traditional CRP methods, for example, only very small amounts of catalyst are required, and the polymerisation is very fast and leads to high molecular weight and low polydispersity. 95 The ability to control precisely molecular weight and tacticity is important because this greatly affects the physical properties of polymers such as toughness, thermal resistance and optical properties.…”

End‐group fidelity of copper(0)‐meditated radical polymerization at high monomer conversion: an ESI‐MS investigation

“…Recently, Percec, Haddleton, and co‐workers have demonstrated that Cu(0)‐mediated radical polymerization (SET‐LRP) displays near perfect bromide end‐group fidelity until relatively high conversion (typically 80%) for various monomers in polar solvents,14, 36–44 thus allowing precise synthesis of complex polymer architectures 24, 45–55. The AGET/ATRP technique in apolar solvents, developed by Matyjaszewski and coworkers,56, 57 enables significant reduction in the amount of metal catalyst used as well as marked improvement in end‐group fidelity (relative to direct ATRP; typically ∼87% end‐group fidelity at 90% monomer conversion) 31, 56, 57.…”

Preparation of polyacrylonitrile via SET-LRP catalyzed by lanthanum powder in the presence of VC

“…However, almost all SET‐LRP studies inevitably introduced catalysts of Cu(0) into the polymerization system . Recently, our group have shown that SET‐LRP could be catalyzed by lanthanide metal such as Sm(0), Yb(0), and Gd(0) …”