Compatibilization of Poly(styrene‐acrylonitrile) (SAN)/Poly(ethylene) Blends via Amine Functionalization of SAN Chain Ends

Styrene/acrylonitrile (SAN) copolymers with low polydispersityM ‾ w /M ‾ n(1.10–1.30) are synthesized by nitroxide mediated polymerization (NMP) in dimethylformamide (DMF) solution with a succinimidyl ester (NHS) terminal group from the N ‐tert‐butyl‐ N ‐[1‐diethylphosphono‐(2,2‐dimethylpropyl) nitroxide] (SG1) residue. These copolymers are thermally stabilized by removing the SG1, and then modified to form primary amine end‐functional SAN (SAN‐NH 2 ). Proton nuclear magnetic resonance spectroscopy ( 1 H NMR) and Fourier‐transform infrared spectroscopy (FT‐IR) indicated that the amine group is effectively placed at the chain end at a level of 90%. SAN‐NH 2 is reactively blended with maleic anhydride grafted poly(ethylene) (PE) at 20 wt.% loading at 180 °C and the resulting morphology is compared against the non‐reactive blend. Scanning electron microscopy (SEM) indicates finer SAN domains ∼ 1 µm which are thermally stable upon annealing in the reactive case. The dispersed SAN domains are reoriented using a channel die to impart elongated domains with aspect ratios ∼ 14, which would be desirable for barrier materials.