Intellectual Merit

1. Synthesis and Characterization of Melt Stable Polyacrylonitrile Copolymers and BlendsJames E. McGrath, Virginia Polytechnic institute and State University, DMR 1006630 Intellectual Merit Poly(acrylonitrile) (PAN) is the basis of the multi-billion pound acrylic fiber textile industry. It has been produced by a solution process, requiring large amounts of organic solvents. More environmentally attractive melt fabrication have been limited by well known side reactions. Our objective is to develop new copolymers, which may be processed below the degradation point. We are investigating the macromolecular architectures and compositions that can be rendered melt stable below about 220C. Early success is shown in Figure 1, where the molecular weight and composition of an AN/MA statistical copolymer of about 40,000K showed a constant fairly stable viscosity for at least 30 mins. The chemistry utilized was classical free radical copolymerizations in either aqueous suspensions or emulsions. We have been exploring controlled radical (RAFT) copolymerizations and it is clear that narrower molecular weight distributions can be achieved, as well as different end groups (Fig. 2). We have demonstrated also that novel graft copolymers can be prepared using methacrylatedpolycaprolactone (PCL) macromonomers Multiphase transition behavior has been demonstrated with the promise of films which display enhanced ductility relative to the non-grafted species (Fig. 3). We have discovered a novel stabilizer, namely boric acid, and we are investigating how it functions via thermal and spectroscopic analyses. Figure 1. Melt Rheology of Controlled Molecular Weight AN-co-MA Statistical Copolymers Figure 2. SEC comparison of AN/MA Copolymers Synthesized by Classical vs. Controlled (RAFT) procedures (narrower MWD) Figure 3. Acrylonitrile/Methyl Acrylate-Poly(Caprolactone)AN-MA-g-PCL Terpolymers; can be synthesized via solution or emulsion polymerization to afford multiphase toughened films

2. Synthesis and Characterization of Melt Stable Polyacrylonitrile Copolymers and Blends James E. McGrath, Virginia Polytechnic institute and State University, DMR 1006630 Broader Impacts & Accomplishments: Current Year • Some important applications of polyacrylonitrile Copolymers, which would be greatly enhanced by more economical and environmentally-sound, solvent-free melt processing. • Carbon Fibers • High AN content • Reinforcing material in composites • Textiles • Copolymer of MA, VA, or MMA • Light stable chemical resistance • Indoor or Outdoor fabrics • Flame-retardant materials • Barrier Film/Multilayer Laminates • Copolymers with acrylates/vinyl acetate • Membranes/fibers for gas separations, waste water and chemical processing McGrath Group August 2011 Our research efforts have long utilized integrating diverse undergraduate and graduate students with widely varying backgrounds. This summer, we enjoyed the visit of Prof. John Mbonifor (pictured with McGrath) from St. Paul’s College (Virginia) and two of his undergraduate students. During this year, NSF support has enabled us to add several PhD students. In particular, two young women have joined the group and have already made contributions to this project.