Effect of Derivatives of ß-substituted Methylenemalonic and Acrylic Acids on the Radical Polymerisation of Cyanoacrylate Monomers

Plasticheskie Mossy, No. 6, 1999, p. 31 Effect oi derivatives of B-substituted methylenemalonic and acrylic acids on the radical polymerisation oi cyanoacrylate monomers A.M. Vetrova, O.N. Klenovich, M.R Badryzlova and A.R Sineokov Translation submitted by P. Curtis Selected from International Polymer Science and Technology, 26, No. 7, I999, re/erence PM 99/06/31; Iransl. serial no. IAIO7 It is well known lreis. l-3) that the high reactivity oi cyanoacrylate monomers toanionicand radical polymerisation is the reason for destabiiisation oi cyanoacrylate adhesive composites during prolonged storage. To improve their stability, it is oi practical interest to study the eiiect oi compounds with conjugated double bonds on the process oiradical polymerisation oidiiierent ix-cyanoacrylates. To this end, we have synthesised derivatives oi B-allxyl-, |3- vinyl-, and Nphenylvinyllcyanoacrylic acid and sorbic, oz- cyanosorbic, methylene- and crotylidenemalonic acids, presented in Table L Compounds 1-3 and 6-12 were produced by the Knevenagel’ reaction by the condensation olthe corresponding aldehydes withderivativesolmalonic acid (rei. A). Monomers A and 5 were synthesised by the reaction of potassium salt oi sorbic acid with allyl and butyl bromide respectively by the procedure described in rel. 5. I The content oi the main substance oi the compounds produced was determined by gas-liquid chromatography and amounted to 99.0-99.5 wt.%. Polymerisation was carried out at a temperature of 60°C in glass ampoules placed in an isothermal microcalorimeter lrei. 6). Each experimentwas repeated three times. The kinetic parameters were calculated ham thermograms obtained during radical polymerisation oi ethoxyethyl cyanoacrylate (EECA), ethyl cyonoacrylate (ECA), and allyl cyanoacrylale Intemationoi Polymer Science and Technology, Vol, 27, No. l, 2000 IACA) inthe presence oi synthesised compounds and without them.The initial polymerisation rate Wi(up to 5% conversion), the maximum polymerisation rate Wm, the time oiachievement oi the maximum rate cm, the polymerisation time beiore its completion I(, and the heat ol polymerisation Q were calculated. Cyanoacrylate monomers containing 95-98 w1.% main substance were additionally puriiied by double vacuum distillation (l 33-266 Pa) and inhibited Willi 0.3 wt.% propanesultone to suppress anionic polymerisation (rei. 7). Dicyclohexylperoxydicarbonate (CPC, TU 6-01 -291 -76) was used as the radical polymerisation initiator, additionally purilied by reprecipitation oian acetone solution oi peroxide into methanol. Changes in the maximum rates, in the time of their achievement, and in the polymerisation time oi ACA as a lunction oi the concentration oi modifying compounds are presented in Figures 1-3 respectively. An analysis oigraphic data makes it possible to place the modifiers in terms oi the ellect ol retardation oi radical polymerisation into three groups: a weakly retarding [I -5); 0 having an appreciable retarding eiiect [6, l l, l2]; 0 effectively retarding (7-10)‘ T/29 Table I Dcrivatirz-5 a/flsiibstiliz/mi nmltylumnalanic and acrylic acid: of gmrral farnmln The results obtained show that the greatest retarding ellect is provided by derivatives ol cyanosorbic acid having in their structure a combination ol coniugated double bonds and two electronegative groups (CN, COOR]. Furthermore, the presence ol an end methyl group is a necessary factor, which follows from a comparison ol the inlluence on retardation oi polymerisation ol compounds 7—l0andcompound3not havingamethylgroup. This makes it possible to assume that the ellectiveness of substitutents 7-10 is determined by the lact that, acting as a chain translerer (transler ol the mobile hydrogen atom ol the methyl group to the growing radical), theybecome unreoctive radicals with a stable resonance structure (refs. 8 and 9). Confirmation ol this scheme is provided by the lact that replacement ol the methyl group with a phenyl group in compounds I 'l and 12 leads to a reduction in this ellect. Amongthederivatives oltx-cyanosorbic acid (7-1 0), there is cl clirect dependence of the process of retardation ol the radical polymerisation of allyl cyanoacrylate on the electronegativity of the group in the (X-poslllon in relation to thecloubleconjugated bond.Thesecompounds canbeplacecl in the following order of stabilising ellect: nitrile-tr cyanosarbate > propargyl-otvcyanosorbate > allyl-u-cyano- sorbate > propyl-otvcyanosorbote. T/.70 R—CH=C 1 X Y Yield. T . .°C No. R x % Tm . °c 0' ‘b°n'1'm_Hg) up” 1 cu} CN coocH2_cH=cH2 65 - 98 (5) l.47l0 2 cl:-17 CN coocH2_cH=c|-12 73 _ 94 (I) L468-1 3 CH1=CH—CH CN CO0CH2—CH=CH1 30 34 - - 4 CH3Cl|=C|I ll C0OCH2—Cll=CH2 50 - 51 (ll L503‘ 5 cu3cn=cn N hooquy so — 33 (2) M915 5 CHJCH=Cl| C00Cl|ZC|l=CHZ C00CH1—CH=CH2 55 - '37 ('0 1-5'35 7 CH3CH=CH CN COOCHZ-CH=CH3 95 52 125 (I) - 3 CH3CH=Cl| CN C00C3ll7 89 37 - - 9 CHJCH=CH CN C00CH2—CsCH 60 56 — — I0 cH3cH=cH CN CN 72 57 - — ll C6H5CH=CH CN CO0CH1—CH=CH1 75 33 - - I2 c6HScH=cH CN CN 72 H9 — — wm x I0’, 395-’ 500 400 300 200 100 Modifier concentration, wv.% Hg. I Dependence of maximum polymerisation lute an concentration oimodmen l-Hdvringracfitalpolymarisation o/ACA: TP=60’C;CPC concentration 0.5 M.% Inte/'notionalPolyn1er Science and Technology, Vol. 27, Na, 1, 2ooo l l l l i I t t 0 1 2 3 4 5 Modifier concentration, wt.% Fig. 2 Dependence amine cfachievemenlofmaximum polymerisation rate on concentration aln-toditiers 1- 12 during radical polymerisaltbn of A01: Tp = 60°C; CPC concentration 0.5 wt.% Thus, the mosteffective inhibitor afthe radical polymerisation of ACA is nitrile-or-cyanosorbate. Investigation ofthe polymerisation of ethyl- and ethoxyethyl- 0:-cyanoacrylates in the presence of derivatives of L1- cyanosorbic acid also confirmed the stabilising effect of these compounds. Table 2 presents kinetic data on the influence of allyl~a-cyanosorbate (AC5) on the radical polymerisation oi ECA and EECA. As can be seen from Table 2, retardation of the polymerisation ol cyanoacrylate monomers is observed with re, mm 150 120 90 60 30 0 1 2 3 4 5 Macllfier cencentmfion, wi.% Fig. 3 Dependence or time of completion ol polymerisation on concenlralioa olmoetmetc 1-12 during tadicalpolyrnerisaliort ofACA: TD - 60°C, CFC concentration 0.5 wt.% an ACA content of 0.1 wt.%, and with 5 wt.% modifier the polymerisation ofEECA is retarded bya factorof 5.5, and the polymerisation of ECA by a factor of 7.5, which indicates the inhibiting power of this compound. Thus, the effect of retardation of radical polymerisation olcyanoocrylatemonomersbyu-cyanosorbicacidderivatives having an end methyl group, a conjugated double bond, and electronegative substituents (CN and COOR) has been found. tntematlonol Pclyniei science and Technology, vol. 27, No. l, 2000 Tabln 2 Itxflutttcz o/‘ACA on radical ptJI_\'tnerixation af EECA and ECA al arc in present: of 0.5 II‘t.‘7v cm: and 0.3 |t'l.% prapanentllalte ACA content, wr.% M Polymerisation 0nDfl'|C|‘ parameters o 0.1 0.5 L0 5.0 EECA iv, x to’. %-s'‘ 2.3 L8 1.3 0.3 0.2 wm x to’. %-s" 4.8 4.0 3.7 2.9 0.4 rm. min 47 55 75 I I2 240 ec_ man 70 so I13 :40 385 Q . kllmol 49.1 50.4 50.3 49.9 50.4 ECA W, x 102. ‘7r>s“ 2.9 2.0 t.0 0.7 0.4 Wm x ml. trons" 40.5 34.4 2| .7 10.7 0.5 cm. min 24 31 55 as 130 cc. min 40 45 77 us 300 Q , kt/ml 55.7 55.2 55.2 56.7 55.2 T/3] The use of such modifiers makes it possible to improve the‘ stability of cyanoacrylate composites during storage by retarding the radical polymerisation of cyanoacrylate monomers. REFERENCES 1. 1732 D.C. Pepper, Macromol. Chem,, 184, No. 2, 1983, p. 383 B. Ryan, Macromol. Chem., 184, No. 2,1983, p. 385 H. Strickor, Archiv der Fharmaric, 300, No. 4, 1967, p. 139 Russian Patent No. 1089927, 1984 Yoneda Shigeo etal., Kogyo Kctgulri Losshi, 69, No. A, I966, p. 641 EP. Komral