Poly(ethylene-co-butylene)-b-(styrene-ran-maleic anhydride)2 Compatibilizers via Nitroxide Mediated Radical Polymerization

Telechelic poly(ethylene-ran-butylene) initiator terminated with [tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino] nitroxide groups (PEB-(SG1)2) was used to initiate the controlled radical copolymerization of maleic anhydride (MA) and styrene (ST). The ST/MA copolymerizations were performed in 1,4-dioxane at 110°C and resulted in PEB-b-P(ST-ran-MA)2 triblock copolymers with relatively narrow molecular weight distributions ( M ¯ m / M ¯ n ≈ 1.5 ) . Gel permeation chromatography (GPC) indicated that the initiator used was ≈93% efficient. The resulting copolymers were then blended as 20 wt.% dispersions in nylon 6 (PA6) at 230°C. With as little as 10 mol.% of MA in the feed to make the PEB-b-P(ST-ran-MA)2, blends were deemed dynamically compatibilized based on the reduced particle size. All of the PEB-b-P(ST-ran-MA)2/PA6 blends resulted in a minor phase particle size D ¯ vs = 0.1 μm while the PEB-b-P(ST)/PA6 blend had D ¯ vs = 1.15 μm (i.e. no MA in the copolymer). Tensile testing revealed yield stresses and strains decreased steadily from pure PA6 to non-reactive PEB-b-P(ST)2/PA6 to PEB-b-P(ST-ran-MA)2/PA6. However, no difference in tensile properties was observed between PEB-b-P(ST-ran-MA)2/PA6 samples made from PEB-b-P(ST-ran-MA)2 copolymer of varying MA content.