Unexpected alternating radical copolymerization of chlorotrifluoroethylene with 3‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate

Abstract

AbstractThe radical solution copolymerization of hexafluoropropylene, chlorotrifluoroethylene (CTFE), vinylidene fluoride, and tert‐butyl‐α‐trifluoromethylacrylate with different monomers bearing isocyanato groups such as allyl isocyanate, 3‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate (m‐TMI), and 2‐isocyanatoethyl methacrylate, initiated by 2,5‐bis(tert‐butylperoxy)‐2,5‐dimethylhexane were studied. Several of these radical copolymerizations were not successful in contrast to that of CTFE with m‐TMI, although m‐TMI monomer does not homopolymerize under radical initiation. The resulting poly(CTFE‐co‐m‐TMI) copolymers were characterized by 1H and 19F nuclear magnetic resonance and Fourier transform infrared spectroscopy and their compositions assessed by elemental analysis. The reactivity ratios of both comonomers were determined by linearization methods of Fineman‐Ross, Kelen‐Tüdös for low conversions of monomers, and by the extended Kelen‐Tüdös method for high monomer conversions. The average values of the monomer reactivity ratios, rCTFE and rm‐TMI, were 0.076 and 0.034 at 130 °C, respectively, depending on these monomer conversions and the applied methods of calculation. In all cases, rCTFE × rm‐TMI product was close to zero, which indicates that poly(CTFE‐co‐m‐TMI) copolymers exhibit a high tendency toward alternation. This was also confirmed by the Igarashi's theory which revealed a high content of CTFE‐m‐MTI heterodyads. The Q and e values for m‐TMI monomer were also assessed (Qm‐TMI = 0.007 and em‐TMI = 0.99). As well as this kinetics of copolymerization, several properties of the obtained fluorofunctional copolymers such as molecular weights (ranging from 1500 to 8200 g mol−1), molecular weight distributions (from 1.2 to 2.1) were also investigated. Their thermal properties revealed satisfactory thermal stability (higher than 250 °C). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2681–2697, 2010