Radical copolymerization of acrylonitrile with 2,2,2‐trifluoroethyl acrylate for dielectric materials: Structure and characterization

Radical copolymerization based on acrylonitrile (AN) and 2,2,2‐Trifluoroethyl acrylate (ATRIF) initited by AIBN was investigated in acetonitrile solution. The resulting poly(AN‐co‐ATRIF) copolymers were characterized by ¹H, ¹³C, and ¹⁹F NMR and IR spectroscopy, and size exclusion chromatography (SEC). Their compositions were assessed by ¹H NMR. The kinetics of radical copolymerization of AN with ATRIF was investigated from sereval experiments achieved at 70 °C from initial AN]₀/ATRIF]₀ molar ratios ranging between 20/80 and 80/20 and was enabled to determine the reactivity ratios of both comonomers. From the monomer—polymer copolymerization curve, the Fineman–Ross and Kelen–Tüdos laws enabled to assess the reactivity ratios (r_AN= r₁ = 1.25 ± 0.04 and r_ATRIF = r₂ = 0.93 ± 0.05 at 70 °C) while the revised patterns scheme led to r₁₂ = r_AN = 1.03, and r₂₁ = r_ATRIF = 0.78 at 70 °C. In all cases, r_AN x r_ATRIF product was close to unity, which indicates that poly(AN‐co‐ATRIF) copolymers exhibit a random structure. This was also confirmed by the Igarashi's and Pyun's laws which revealed the presence of AN‐ATRIF, AN‐AN, and ATRIF‐ATRIF dyads. The Q and e values for ATRIF were also assessed (Q₂ = 0.62 and e₂ = 0.93). The glass transition temperature values, T_g, of these copolymers increased from 17 to 61 °C as the molar percentage of ATRIF decreased from 77 to 16% in the copolymer. Thermogravimetry analysis of poly(AN‐co‐ATRIF) copolymers showed a good thermal stability compared to that of poly(ATRIF) homopolymer due to incorporation of AN comonomer. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3856–3866