Cover Picture: Macromol. React. Eng. 2/2014

Abstract

Cover: Amine end‐functional poly(styrene‐co‐acrylonitrile) (SAN) copolymers are synthesized using nitroxide mediated polymerization for use in reactive extrusion with maleic anhydride grafted poly(ethylene) (PE). Such SAN copolymers are envisioned as alternative barrier polymers with controlled microstructure for PE matrices. Further details can be found in the article by K. J. Oxby and M. Marić http://doi.wiley.com/10.1002/mren.201200081.

Reactive compatibilization of poly(methyl acrylate‐ran‐acrylonitrile)/poly(ethylene) blends through amine–anhydride coupling

“…The shear rates were approximated as 9 and 27 s −1 at 50 rpm in the region with the minimum and maximum diameter, respectively, by using the screw speed, gap distance and, screw diameter. Using the data obtained and data previously measured, it can be seen that the η r of the non‐reactive system copolymer: PE‐ g ‐MAn = 0.19–0.23 and that of the reactive terpolymer: PE‐ g ‐MAn was 0.3–0.6 at the low and high shear rates estimated in the extruder. η r approaching unity should theoretically result in the minimum domain sizes .…”

“…Even using completely functional terpolymer, without dilution with non‐functional copolymer, and having η r close to unity, we were not able to achieve sub‐micron dispersions. Further, we had several amino groups per chain and we were still unable to reduce the particle size as we did earlier with a single amino group at the end of a styrene/acrylonitrile copolymer chain . One key difference that may explain our results is that the amine on the p ‐amino styrene monomer was an aniline, which does not react as quickly as a primary aliphatic amine .…”

“…Seeing that for the functionalized blends decreased relative to the non‐functionalized blend, it shows that morphology was stabilized due to the coupling reaction as was suggested by previous studies . Conversely, the small increase in after annealing indicates that coalescence was very slow at the temperature used, and that slight variations in were more likely to be caused by particle analysis, rather than the coalescence process . To compare the particle sizes with theoretical or semi‐empirical predictions, estimates of the blend interfacial were necessary.…”

“…Indeed, styrene/acrylonitrile (SAN) and methyl acrylate/acrylonitrile (MA/AN) copolymers are commercially available as barrier materials synthesized by conventional radical polymerization, however little is mentioned how these are compatibilized . We previously made SAN copolymers where we placed a single reactive amine group at the chain end . The amine‐terminated SAN was effective in compatibilization with maleic anhydride grafted PE (PE‐ g ‐MAn) and we were able to form elongated SAN domains in the PE .…”

“…We previously made SAN copolymers where we placed a single reactive amine group at the chain end . The amine‐terminated SAN was effective in compatibilization with maleic anhydride grafted PE (PE‐ g ‐MAn) and we were able to form elongated SAN domains in the PE . However, the dispersed phase particle size was limited to about 2 μm and further modulation could potentially be accessed by making the acrylonitrile‐containing copolymer with many pendant functional groups and perhaps diluting it with cheaper non‐functional SAN.…”