Effect of silicon, germanium and tin compounds on copolymerization of unsaturated acids

Problems of control of the reactivity of macroradicals and the growth of polymer chains

“…A similar mechanism involving an eight-membered reaction complex has been proposed by Kabanov 50 to interpret the increase in the propagation rate constant in the polymerisation of MMA in the presence of metal halides and by Smirnova and coworkers, 51,52 who studied copolymerisation of acrylic acid with VA (vinyl acetate) in the presence of germanium salts. In our opinion, the above-presented reaction complex [see Eqn (3)], which includes the allylic delocalised macroradical is thermodynamically and geometrically more stable.…”

Copolymerization of vinyl acetate and unsaturated acids in the presence of germanium tetrachloride in methanol

“…However, this effect is more pronounced for the VA-AA copolymerization: In particular, parameter r 2 , which characterizes the reactivity of acid, is reduced by a factor of 27 for AA; in the case of MAA, this drop is as low as a factor of 1.3. Note that a significant decrease r 2 (by a factor of 7) was observed also for the bulk VA-MAA copolymerization in the presence of GeCl 4 [1]. Such a change in r 2 in the presence of GeCl 4 may be explained solely by an increase in the rate constant of cross propagation, an effect that may be one of the causes of the alternating copolymeriza tion of VA and AA.…”

“…The nature of the complexes in the alternating copolymerization of VA and AA in the presence of GeCl 4 was ascertained via ESR spectroscopy [7] a few years after the publication of [1,2]. Polymerization was conducted directly in ampoules of an ESR spec trometer during UV irradiation.…”

“…Earlier [1], catalytic amounts of silicon and germa nium compounds were shown to affect the composi tion of copolymers of acrylic acid (AA) and meth acrylic acid (MA) with a number of vinyl monomers [1]. The most noticeable effects were observed in the case of germanium chloride; silicon chloride; and their hydrides, Cl 3 SiH and (CH 3 ) 2 ClSiH.…”

“…VA was successively dried over anhydrous CaCl 2 and calcium hydride and then distilled at atmospheric pressure (Т b = 72-73°С, = 1.3950). AA and MAA were degassed through two freeze-pump-thaw cycles 1 This work was supported by the Russian Foundation for Basic…”