Acrylates reactivity ratios

Kress, A.O., Mathias, L.J. and Cei, G., Copolymers of styrene and methyl a-(hydroxymethyl)acrylate reactivity ratios, physical behavior, and spectral properties, Macromolecules, 1989, 22, 537. 

Irrespective of the coupling between the ethene and acrylate reactivity ratios, individual Arrfienius plots of these parameters have been made. Figure 4.6-11 shows this data for E-MA, E-BA, and E-EHA copolymerizations at 2000 bar. The ethene reactivity ratios are rather similar for the three systems, whereas the... 

Because of the relatively large uncertainty in acrylate reactivity ratio (rp,) determination there is no easy access to reliable AV (rA) values. A few experiments [27,46] have, however, been carried out to estimate AV (rE). The numbers obtained for the E-MA and E-EHA systems are AV (rE) = -(7.4 4.1) cm mol" and AV (rE) = -(8.2 3.5) cm mol", respectively. A recently reported value of AV4(rE) for the ethene-butyl methacrylate system is -(6.0 3.9) cm moP [51]. Negative AV (rE), as observed for all ethene-acrylate systems, says that Te, which is well below unity, increases with pressure. 

Figure 21 Arrhenius plots of ethene and acrylate reactivity ratios and Ta, respectively, for copolymerization of the binary systems E-MA (triangles), E-BA (squares), and E-EHA (circles) at 2000bar. The dashed lines represent the fit to the combined data set for E-BA and E-EHA. Erom Buback, M. Drdge, T. van Herk, A. Mahling, E.-O. Macromol. Chem. Phys. 1996, 197, 4119. ...

The data in Table 7.6 list the mole fraction of methyl acrylate in the feedstock and in the copolymer for the methyl acrylate (Mi)-vinyl chloride (M2) system. Use Eq. (7.54) as the basis for the graphical determination of the reactivity ratios which describe this system. 

GopolymeriZation. The importance of VDC as a monomer results from its abiHty to copolymerize with other vinyl monomers. Its Rvalue equals 0.22 and its e value equals 0.36. It most easily copolymerizes with acrylates, but it also reacts, more slowly, with other monomers, eg, styrene, that form highly resonance-stabiHzed radicals. Reactivity ratios (r and r, with various monomers are Hsted in Table 2. Many other copolymers have been prepared from monomers for which the reactivity ratios are not known. The commercially important copolymers include those with vinyl chloride (VC),... 

Vinyhdene chloride copolymerizes randomly with methyl acrylate and nearly so with other acrylates. Very severe composition drift occurs, however, in copolymerizations with vinyl chloride or methacrylates. Several methods have been developed to produce homogeneous copolymers regardless of the reactivity ratio (43). These methods are appHcable mainly to emulsion and suspension processes where adequate stirring can be maintained. Copolymerization rates of VDC with small amounts of a second monomer are normally lower than its rate of homopolymerization. The kinetics of the copolymerization of VDC and VC have been studied (45—48). 

The influence of radiation dose on the polymer composition and the swelling degree of (pAM-DAEA-HCl) are shown in Table 3. The results show that the percent of acrylamide in the copolymer is higher than that of the amine. This can be attributed to smaller reactivity ratios of monomers of diallylammonium salts relative to acryl-... 

Various methylene derivatives of spiroorthocarbonates and spiroorthocstcrs have been reported to give double ring-opening polymerization e.g. Scheme 4.36). Like the parent monocyclic systems, these monomers can be sluggish to polymerize and reactivity ratios are such that they do not undergo ready copolymerization with acrylic and styrenic monomers. Copolymerizations with VAc have been reported.170 These monomers, like other acetals, show marked acid sensitivity. 

In this copolymerization, the reactivity ratios are such that there is a tendency for S and the acrylic monomers to alternate in the chain. This, in combination with the above-mentioned specificity in the initiation and termination steps, causes chains with an odd number of units to dominate over those with an even number of units. 

Monomers not amenable to direct homopolymerization using a particular reagent can sometimes be copolymcrizcd. For example, NMP often fails with methacrylates (e.g. MMA, BMA), yet copolymerizalions of these monomers with S are possible even when the monomer mix is predominantly composed of the methacrylate monomer,15j This is attributed to the facility of cross propagation and the relatively low steady state concentration of propagating radicals with a terminal MMA (Section 7.4.3.1). MMA can also be copolymerized with S or acrylates at low temperature (60 C).111 Under these conditions, only deactivation of propagating radicals with a terminal MMA unit is reversible, deactivation of chains with a terminal S or acrylate unit is irreversible. Molecular weights should then be controlled by the reactivity ratios and the comonomer concentration rather than by the nitroxide/alkoxyamine concentration. 

For the remaining three systems, styrene-vinyl acetate, vinyl acetate-vinyl chloride, and methyl acrylate-vinyl chloride, one reactivity ratio is greater than unity and the other is less than unity. They are therefore nonazeotropic. Furthermore, since both ri and 1/7 2 are either greater than or less than unity, both radicals prefer the same monomer. In other words, the same monomer—styrene, vinyl chloride, and methyl acrylate in the three systems, respectively—is more reactive than the other with respect to either radical. This preference is extreme in the styrene-vinyl acetate system where styrene is about fifty times as reactive as vinyl acetate toward the styrene radical the vinyl acetate radical prefers to add the styrene monomer by a factor of about one hundred as compared with addition of vinyl acetate. Hence polymerization of a mixture of similar amounts of styrene and vinyl acetate yields an initial product which is almost pure polystyrene. Only after most of the styrene has polymerized is a copolymer formed... 

Here r am is the reactivity ratio of an acrylamide radical with acrylamide and acrylic acid and Q is the ratio of acrylamide and acrylic acid in the monomer mixture from which the copolymer was derived. Thus, the determination of k. for at least three copolymers allows a derivation 1of k, k. and k . With this approach we found k- /k, = 0.11 and k2/k = 0.013. 

Table 5. Monomer reactivity ratios of alkyl acrylates and MMA...

Bajoras and Makuska investigated the effect of hydrogen bonding complexes on the reactivities of (meth)acrylic and isotonic acids in a binary mixture of dimethyl sulfoxide and water using IR spectroscopy (Bajoras and Makuska, 1986). They demonstrated that by altering the solvent composition it was possible to carry out copolymerization in the azeotropic which resulted in the production of homogeneous copolymers of definite compositions at high conversions. Furthermore, it was shown that water solvent fraction determines the rate of copolymerization and the reactivity ratios of the comonomers. This in turn determines the copolymer composition. 

Compositionally uniform copolymers of tributyltin methacrylate (TBTM) and methyl methacrylate (MMA) are produced in a free running batch process by virtue of the monomer reactivity ratios for this combination of monomers (r (TBTM) = 0.96, r (MMA) = 1.0 at 80°C). Compositional ly homogeneous terpolymers were synthesised by keeping constant the instantaneous ratio of the three monomers in the reactor through the addition of the more reactive monomer (or monomers) at an appropriate rate. This procedure has been used by Guyot et al 6 in the preparation of butadiene-acrylonitrile emulsion copolymers and by Johnson et al (7) in the solution copolymerisation of styrene with methyl acrylate. 

Ferrocenylmethyl acrylate (FMA) and 2-ferrocenylethyl acrylate (FEA) have been synthesized and copolymerized with styrene, methyl acrylate, and vinyl acetate [C. U. Pittman, Jr., Macrmolecules, 4, 298 (1971)]. The following monomer reactivity ratios were found ... 

Reactivity ratios between acrylated lignin model compound (Fig. 2), defined as Mi, with either MM A or S, defined as M2, were determined experimentally in accordance with standard procedures (15). These involve mixing two different vinyl monomers in various molar ratios with catalyst (i.e., benzoyl peroxide) and solvent, heating the mixture to achieve polymerization, and recovering the polymer by the addition of non-solvent, and centrifugation. The respective molar monomer fractions of the copolymer were determined by UV-spectroscopy in the cases where MMA served as M2, and by methoxyl content analysis in those cases in which S was the M2-species. The results were subjected to numerical treatments according to the established relationships of Kelen-Tiidos (17) and Yezrielev-Brokhina-Roskin (YBR) (18), and this is described elsewhere (15). 

Table I. Experimental Reactivity Ratios between Acrylated Lignin Model Compounds and MMA and S...

A second test was done by using butyl acrylate as the comonomer as shown in Figure 11. The reactivity ratios in this case are such that the methacrylate functionality would react slower with acrylates than with vinyl chloride. As predicted the butyl acrylate is at 62% conversion before the MACROMER peak is significantly diminished. These data add validity to the hypothesis that the placement of side chains in the backbone is dependent on the terminal group of the macromonomer and the relative reactivity of its comonomer. 

In order to overcome the reactivity ratio problem of AA, the use of acrylic monomers, such as -butyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate, N-methylol acrylamide, and acrylamide have been suggested (14,15). Also, the use of water insoluble comonomers based on acrylamide has been described (16). 

The co-monomers such as vinyl acetate, acrylate esters, or carbon monoxide are fed together with ethylene, or introduced by liquid pumps, into the suction of the secondary compressor. The concentration in the feed of the co-monomer which is required to achieve a certain level of the co-monomer in the resulting polymer depends on the reactivity ratios, ri and r2, which are the ratios of rate constants of chain-propagation reactions [5]. The values for the co-monomers used in the high-pressure process are presented in Table 5.1-3. In the case of vinyl acetate, both reactivity ratios are identical and therefore the composition of the copolymer is the same as that of the feed. The concentration of vinyl acetate, for example, in... 

J 5. Jordan, E. F., K. M. Doughty, and W. S. Port Polymerizable derivatives of long-chain alcohols. II. Reactivity ratios for the copolymerisation of some alkyl acrylates. J. Appl. Polymer Sci. 4, 203 (1960). 

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