Abstract
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-T€udos laws enabled to assess the reactivity ratios (rAN5 r1 5 1.25 6 0.04 and rATRIF 5 r2 5 0.93 6 0.05 at 70 C) while the revised patterns scheme led to r12 5 rAN 5 1.03, and r21 5 rATRIF 5 0.78 at 70 C. In all cases, rAN x rATRIF 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 5 0.62 and e2 5 0.93). The glass transition temperature values, Tg, 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.