The thermal behaviours of zinc, cobalt, nickel and copper acrylates and their polymers were investigated. It was found that the decompositions of these compounds are complex processes. The main decomposition of the monomer was preceded by thermal polymerization. The thermal effect of this reaction was greater for zinc acrylate than for the other salts. The reaction orders and activation energies of decomposition of the monomers and the polymers were calculated and the differences discussed.In recent years metal-containing monomers and polymers have been subject to increasing interest. This is due to a number of valuable properties shown by coordination polymers and ionomers. The area of applications of such polymers is very broad and among their characteristic features are chemical resistence and thermal stability. Metal derivatives of polymers containing COOH groups are among the best known.The thermal behaviours of some monovalent and divalent metal acrylates have been reported [1 ]. Monomers containing divalent transition metals may be especially interesting for the preparation of coordination polymers and ionomers. In the present paper, therefore the thermal decompositions of zinc(ll), cobalt(ll}, nickel{ll) and copper(ll} acrylates and of their polymers were investigated and the results compared. Experimental Preparation of metal acrylatesMetal acrylates were prepared by the reaction of acrylic acid (5-10 wt.% stoichiometric excess) with zinc oxide, basic cobalt carbonate, basic nickel carbonate and cupric hydroxide, respectively, in toluene suspensions at 40-50 ~ . The reactions were carried out for 5 h, with gradual addition of the reactants and with constant stirring. The evaporated toluene lost from the reaction vessel was constantly replaced. Water formed in the reactions was removed as an azeotropic mixture with toluene.7inc, copper and cobalt acrylates were washed with toluene and then dried in a vacuum drier at 40-50 ~ Nickel acrylate, after a preliminary drying, was ground, washed with acetone and finally vacuum-dried like the other monomers.

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The radical copolymerization of styrene with Zn(II), Co(II), Ni(I1) and Cu(I1) acrylates in methanol at 60°C was studied and that of styrene with Cu(I1) acrylate also in acetonitrile at 80 "C. In a given period of time an increase of conversion was observed with increasing concentration of the first three metal acrylates in mixtures with styrene. With Cu(I1) acrylate, however, a decrease of conversion was found. The monomer reactivity ratios were determined as follows: rst = l,lO, rAIZn = 0,90; rst = 1,74, rAlc0 = 036; rst = 1,83, rAZNi = 0,53; rst = 5,94, rAlcu = 0,12 (in acetonitrile). The products of the reactivity ratios, almost equal to one, reflect an "ideal" copolymerization and therefore a very little alternating tendency in propagation reactions. The Alfrey-Price Q-e parameters for the metal acrylates were calculated and discussed. Experimental partMaterials: Styrene, acrylic acid, methanol, and acetonitrile, all commercial grade, were purified according to standard procedures. 2,2'-Azoisobutyronitrile (AIBN) (from Koch-Light Labs., England) was recrystallized twice from methanol (m.p. = 103 "C).The preparation of the metal acrylates has been described previo~sly'~). Copolymerizations:A four-necked reaction flask was used, equipped with a reflux condenser, a stirrer, a thermometer and a nitrogen inlet. The comonomer feed was thermostated for 0,5 h at a fixed termperature under nitrogen atmosphere before a given amount of AIBN a) Presented at the 2!Fh IUPAC MACRO 83 Symposium on Macromolecules, Bucharest, 5 -9September 1983.

Radical copolymerizations of styrene with acrylates of magnesium, calcium, strontium and barium were carried out in dimethyl sulfoxide. The monomer reactivity ratios were determined by the Yezrielev-Brokhina-Roskin and the Kelen-Tud& methods. In all cases the monomer reactivity ratio for styrene exceeded one and those for the salts were less than one. The Q-values of the Alfrey-Price scheme for the metal acrylates were within the range 0,l -0,2. For the values of the polarity parameter e the following sequence was found: eMgA, < eCaA, < eSrA, < eBaA, and the tendency for alternation in copolymerizations increased in the same order. The results indicate that the course of copolymerizations under study is predominantly affected by polarization of the vinyl groups in the salts.

On the basis of factorial method of experiment design the radical polymerization of cobalt and nickel acrylate in dimethylformamide solution has been studied. The influence of the kind of metal in the acrylate on the values of the constants in the overall polymerization equation has been revealed.