I
C. C. UNRUH and T.
M. LAAKSO
Research Laboratories, Eastman Kodak
Co., Rochester, N. Y.
Copoly merizabiIity of Ethyl AI pha-Acetoxya cry1a te Ethyl a-acetoxyacrylate resembles ethyl acrylate very closely in copolymerizability, rather than vinyl acetate
AN study of the polymerization and copolymerization behavior of EARLIER
alkyl a-acyloxyacrylates presented evidence that such monomers more nearly resembled acrylic and methacrylic esters than vinyl esters in their copolymerization characteristics (2). This study has been extended to a more quantitative investigation of the copolymerization behavior of ethyl a-acetoxyacrylate with four different monomers-styrene, methyl methacrylate, vinyl acetate, and ethyl acrylate. The a-acetoxyacrylate may be considered to be structurally related to both ethyl acrylate and vinyl acetate. The present article is a synopsis of the quantitative results obtained in this investigation, with a brief interpretation of these data. The procedure followed is the conventional one used in the determination of rl and r2 reactivity ratios for a given pair of comonomers copolymerized by a free radical initiation ( 7 ) . The temperature of copolymerization was 60’ C., with approximately O.lOyo of benzoyl peroxide as initiator. The rl and r2 values were calculated from the equation
r2
=
M,
[z
(1 f M l&7i)
-11
using the graphical method of solution described by Mayo and Lewis ( 3 )
Table 1.
mole fraction of monomer 1 in monomer mixture Ma = mole fraction of ethyl aacetoxyacrylate in monomer mixture rn1 = mole fraction of monomer 1 in copolymer m2 = m‘ole fraction of ethyl aacetoxyacrylate in copolymer The reactivity ratios, r l and rz, obtained in the case of copolymerization with each monomer are summarized in Table I. The values of rl and r2 for each comonomer pair were substituted in the following equations, to obtain the values of Q 2 and e2, for ethyl a-acetoxyacrylate (7) : TI = (QI/Qz) exp (-el(ei - e d l and r2 = (Qz/Qi) exp (-ez(ez - el)) or I n ( r l r 2 ) = -(el - ez)2 iM1
=
The values of Q1 and e l in the solution of the equation just given, suggested by Price ( 4 ) for the monomers used, represent arbitrary values assigned to these monomers, indicating, respectively, the degree of conjugation of the double bond with other groups in the monomer and the electron-donating or electron-accepting nature-i.e., the polarity of the substituents at the double bond. The reference monomer, styrene, is assigned the values Q = 1.0 and e = -0.8.
Copolymerization Reactivity Ratios of Ethyl a-Acetoxyacrylate with Various Monomers at 60” C.
M, Styrene Methyl methacrylate Vinyl acetate Ethyl acrylate
1 124
where
rl
rz
rm
0.57 f 0.05 1.65 =t0.07 0.08 0.03 1.0 =k 0 . 1
0.20 0.05 0.65 zk 0.05 5.4 i 0.5 1.0 rt 0.05
+
0.114 1.07 0.431 1.00
M 2
Ethyl Ethyl Ethyl Ethyl
a-acetoxyacrylate a-acetoxyacrylate a-acetoxyacrylate a-acetoxyacrylate
INDUSTRIAL AND ENGINEERING CHEMISTRY
*
Values of Q and e for ethyl a-acetoxyacrylate are tabulated in Table 11.
Table II. Q and e Values for Ethyl a-Acetoxyacrylate Derived from Copolymerization Data Comonomer Used Styrene Methyl methacrylate Vinyl acetate Ethyl acrylate
Q
e
0.54 0.53
0.67
0.27 0.42
0.66 0.62 0.60
These data clearly indicate that ethyl a-acetoxyacrylate resembles ethyl acrylate very closely in its copolymerizability. Values of Q = 0.42 and e = 0.57 have been calculated for this monomer (5). There is little resemblance to vinyl acetate, the Q and e factors for this monomer being different: 0.028 and - 0.3, calculated from copolymerization data involving methyl acrylate (4). Again, the rl and rz reactivity ratios derived from various comonomer pairs suggest strongly that ethyl a-acetoxyacrylate resembles ethyl acrylate in its copolymerization behavior rather than vinyl acetate.
Literature Cited (1) .4lfrey, T., Jr., Bohrer, J. J., Mark, H..
“Copolymerization,” Xew York, 1952. (2) Laakso, T. M., Unruh, ENG.CHEM.50,1119-23 (3) Mayo, F. R., Lewis, F.
Interscience. C. C., IND.
(1 958). H., J . Am. Chem. Sac. 66, 1594 (1944). (4) Prc;48y. C., J . Polymer Sci. 3, 772
(5) Vanderhoff, J. W., thesis, Univ. of Buffalo, 1951.
Communication 1936 from Kodak Research Laboratories. Complete article accepted for publication in J . Polymer Sci.
