New Star-Branched Poly(acrylonitrile) Architectures: ATRP Synthesis and Solution Properties

Atom transfer radical polymerization (ATRP) has been chosen as ‘‘living’’/controlled free radical polymerization system to synthesize a number of novel poly(acrylonitrile) (PAN) architectures. The reaction conditions for the synthesis of linear samples with control over molar mass and molar mass distribution have been investigated together with the possibility of obtaining copolymers of acrylonitrile with small quantities of methyl acrylate (max. 5 mol-%). Well-defined star polymers with 3, 4 and 6 arms have been successfully synthesized together with linear chains initiated by a bifunctional initiator and star-branched polymers with a hyperbranched poly(ester amide) as core. Molar masses were determined by NMR and GPC with the latter leading to a significant over estimation. Solution viscosity studies indicated that the stiff structure of the PAN chains is still maintained in the homopolymer star architectures and that the incorporation of small quantities of methyl acrylate as comonomer has a stronger effect on chain flexibility than the incorporation of star-branch points.