Polystyrene with trifluoromethyl units: Monomer reactivity ratios, thermal behavior, flammability, and thermal degradation kinetics

Abstract

Chemical modification based on incorporation of flame retardants (FR) into the polymer backbone was used in order to reduce polystyrene flammability. 3‐(trifluoromethyl)styrene (StCF3) and 3,5‐bis(trifluoromethyl)styrene (St(CF3)2) were applied as reactive FR. Copolymers were synthesized with different feed ratios and it gave series of copolymers with various amounts of StCF3 and St(CF3)2 (5–50% mol/mol of St). Glass transition temperature (Tg) and thermal stability of obtained (co)polymers were determined from differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Kinetic parameters such as the thermal decomposition activation energy (E) and frequency factor (A) were estimated by Ozawa and Kissinger models. Pyrolysis combustion flow calorimeter (PCFC) was applied as a tool for assessing the flammability of the synthesized (co)polymers. Relative reactivity ratios were determined by applying the conventional linearization Jaacks method (rSt = 1.34, rStCF3 = 0.54), (rSt = 0.47, rSt(CF3)2 = 0.13). The results suggest that incorporation of fluorinated styrenes into PSt enchance flame retardance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42839.

May Trifluoromethylation and Polymerization of Styrene Occur from a Perfluorinated Persistent Radical (PPFR)?

“…used DSC analysis showing endothermal peaks, the thermal stabilities of polystyrenes were determined by thermogravimetric analysis (TGA) under air and the results are listed in Table 2. All TGA thermograms of CF 3 ‐poly(St‐CF 3 ‐ ran‐ St) copolymers (Figure S13) exhibit the same one step‐degradation starting from around 330 °C and show that the presence of CF 3 on the aromatic ring of styrene does not affect the thermal degradation of polystyrene [58] . The first derivative (DTG) thermograms of t Bu‐C 6 H 10 ‐OC(O)‐ O‐ PSt (Figure S14) display two degradation steps.…”

“…Due to the high styrene amount in the medium, CF 3 -(St-CF 3 )C reacts with styrene to allow the growth of polystyrene. In addition to the excess of styrene, its electron-donatingb ehavior enhances the preference of the radical intermediate to react onto styrene rather than with St-CF 3 .T he consequenceso ft his phenomenon were noted in 2015 in the kinetics of the radicalc opolymerization of both comonomers [58] that showedt hat styrene homopolymerizes faster than St-CF 3 does (r St = 1.34 and r StCF3 = 0.54 at 60 8C). [58] However, this study contradicts an older one, published in 1958, that supplied the followingv alues: r St = 0.70 and a r StCF3 = 1.05 at 60 8C.…”

“…In addition to the excess of styrene, its electron-donatingb ehavior enhances the preference of the radical intermediate to react onto styrene rather than with St-CF 3 .T he consequenceso ft his phenomenon were noted in 2015 in the kinetics of the radicalc opolymerization of both comonomers [58] that showedt hat styrene homopolymerizes faster than St-CF 3 does (r St = 1.34 and r StCF3 = 0.54 at 60 8C). [58] However, this study contradicts an older one, published in 1958, that supplied the followingv alues: r St = 0.70 and a r StCF3 = 1.05 at 60 8C. [59] In the case of a[ PPFR]/[St] molar ratio of 3:1, trifluoromethylation affects alarger quantity of styrene, permitting, at first, ap ropagation with af ew number of Scheme3.Putative mechanism of the trifluoromethylation and (co)polymerizationo fs tyrene initiated with CCF 3 radical generated in situ from PPFR at 90 8Cwith R = Ho rC F 3 .…”

“…All TGA thermograms of CF 3poly(St-CF 3 -ran-St) copolymers ( Figure S13) exhibit the same one step-degradation startingf rom around3 30 8Ca nd show that the presence of CF 3 on the aromatic ring of styrene does not affect the thermal degradation of polystyrene. [58] The first derivative( DTG) thermogramso ftBu-C 6 H 10 -OC(O)-O-PSt (Figure S14) display two degradation steps. The first one, before 300 8C, corresponds to the degradation of the tBu-C 6 H 10 -OC(O)-Oe nd group consistent to the decomposition of aliphatic (poly)carbonate between 200 and2 50 8C [65] (considered as an "unzipping" degradation starting from the end-group) while the second one matches with ad egradation of PSt, assigned to as cissoring of the polystyrene backbone.…”

Aromatic fluorocopolymers based on α-(difluoromethyl)styrene and styrene: synthesis, characterization, and thermal and surface properties

“…12 On the other hand, the incorporation of uorinated units into aromatic polymer chain may enhance some other physico-chemical properties. 13 In the past decades, much attention has been focused on the synthesis and (co)polymerization of styrenic monomers either bearing uorine atoms/uorinated substituents on the aromatic ring [14][15][16] or at its external double bond. 17 In 1949, Cohen et al 18 developed a rst efficient synthesis of a,b,b-triuoro-styrene (TFS), whereas Prober, 19 Narita et al 20,21 and Steck and Stone 22 studied its reactivity in copolymerizations with various olens.…”