1,3,5,5‐tetraphenyl‐Δ³‐1,2,4‐triazolin‐2‐yl radical–properties in the controlled radical polymerization of poly(methyl methacrylate) and polystyrene

Abstract

The triazoline derivative 1 was used as an additive in the chain-growth controlled radical polymerization of vinylic monomers to afford narrowly distributed polymers. This new system is applicable to styrene as well as to methacrylates. The monomer consumption and the variation of the molar mass were monitored with time. Thermal properties of the obtained polymers were also studied. After isolation of the polymers, the growth of the chains was re-initiated in the presence of a second monomer and yielded block copolymers.

Reversible chain transfer catalyzed polymerization (RTCP): A new class of living radical polymerization

“…Examples are listed in Scheme 2. They include sulfur compounds (Scheme 2a [9] and g [10]), stable nitroxides (b) [11][12][13], stable nitrogen and carbon compounds (c) [14][15][16][17], transition metal complexes (d) [18,19], iodine (e) [20], halogens with transition metal catalysts (f) [21][22][23], and tellurium, stibine, and bismuth compounds (h) [24][25][26].…”

“Self-regulation” of controlled radical polymerization

“…As we have shown before [4], the radical polymerization in the presence of triazolinyl radicals fulfills the requirements of a controlled process. A linear increase of the conversion with reaction times, an increase of the molecular weight versus conversion and narrow polydispersity indices have been obtained.…”

“…To prevent the presence of different initiating species, benzoyl peroxide (BPO), was used as initiator, since BPO is known to initiate mainly by phenyl radicals [6]. As we previously reported [4], controlled polymerization of MMA in the presence of triazolinyl 1 to high conversions and to molecular weights up to 100 000 can be achieved. An increase of the molar masses versus conversion is observed while polydispersity indices decrease to 1.2, well below the theoretical limit of 1.5 for free radical polymerization.…”

“…Our primary work dealt with the preparation of homoand block-copolymers by controlled radical polymerization in the presence of triazolinyl radicals [4]. This proved to be a suitable system to test the mechanism proposed above.…”

Application of Stable Radicals as Mediators in Living‐Radical Polymerization

“…Triazolinyl radical 16 decomposes at elevated temperatures generating a phenyl radical that is capable of initiating polymerization. 132 More importantly, this slow, high temperature decomposition prevents the accumulation of excess triazolinyl radicals that occurs as a result of unavoidable chain termination reactions. In comparison to living-radical polymerizations performed using nitroxides, triazolinyl-mediated polymerizations typically produce polymers with broader molecular weight distributions, a result of premature chain termination that occurs in the early stages of the polymerizations.…”