Reactivity ratios terpolymers

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. 

In the pmr data for the terpolymer, overlap between the CH3 absorption of the oxime ester and the backbone absorption is greater than in the copolymer pointed out in Figure k. Thus, while the agreement between the Raman and pmr data for the terpolymer is not very good, (lT-32 difference), it is completely within the experimental error of the pmr data. This large error and the fact that pmr can only distinguish two of the components of the terpolymer demonstrate that it is unsuited for compositional analysis of this system. Based on the agreement with published reactivity ratios and with the elemental analysis of the P(M-CN) copolymer, it is assumed that the Raman data are more accurate. 

The polymerization of a mixture of more than one monomer leads to copolymers if two monomers are involved and to terpolymers in the case of three monomers. At low conversions, the composition of the polymer that forms from just two monomers depends on the reactivity of the free radical formed from one monomer toward the other monomer or the free radical chain of the second monomer as well as toward its own monomer and its free radical chain. As the process continues, the monomer composition changes continually and the nature of the monomer distribution in the polymer chains changes. It is beyond the scope of this laboratory manual to discuss the complexity of reactivity ratios in copolymerization. It should be pointed out that the formation of terpolymers is even more complex from the theoretical standpoint. This does not mean that such terpolymers cannot be prepared and applied to practical situations. In fact, Experiment 5 is an example of the preparation of a terpolymer latex that has been suggested for use as an exterior protective coating. 

Wamsley, A., Jasti, B., Phiasivongsa, P., and Li, X. Synthesis of random terpolymers and determination of reactivity ratios of IV-carboxyanhydrides of leucine, (1-benzyl aspartate, and valine. J. Polymer Sci. [A] Polymer Chem. 42 317—325, 2004. 

Calculate the composition (mole fractions) of the initial terpolymer which would be formed from the radical polymerization of a feed containing 0.414 mol fraction methacrylonitrile (MAN), 0.424 mol fraction styrene (S), and 0.162 mol fraction alpha-methylstyrene (AMS). Reactivity ratios are ... 

A thermosetting appliance enamel consists of a terpolymer comprising about 72 parts of vinyl toluene (70/40 meta/para) with about 20 parts of ethyl acrylate (to reduce brittleness of the copolymer) and 8 parts of an acidic vinyl comonomer. The acid is incorporated in the copolymer to provide sites for subsequent cross-linking with a diepoxide. It seems reasonable to expect that grease and slain resistance of the cross-linked enamel will be enhanced if the cross-links are not clustered and almost all initial polymer molecules contain at least one or a few cross-linking sites. To achieve this in a batch copolymerization, what are the best reactivity ratios (approximately) of the major component (vinyl toluene) and the vinyl acid comonomer Show you reasoning. 

In Table 1 the experimental compositions of some terpolymers are compared with the values calculated by means of the Alfrey-Goldfinger eqs. (7). The values of the reactivity ratios are reported in Table 2. 

It is possible to calculate for which values of [MJ, [MJ and [M3] the alternation degree reaches its maximum (40). In general such values of the monomer concentrations are rather complicated functions of the reactivity ratios. It can be said that, when the alternation is maximum, the average sequence length is the Same for all the monomers. Unlike in the case of binary copolymerization, the maximum alternation does not always correspond to the composition at which the monomers are present in the terpolymer in equimolecular amounts. 

We have previously reviewed ( 1, 2) the methods used to calculate structural features of copolymers and terpolymers from monomer reactivity ratios, monomer feed compositions and conversions, and have written a program for calculating structural features of copolymers from either terminal model or penultimate model reactivity ratios (3). This program has been distributed widely and is in general use. A listing of an instructive program for calculating structural features of instantaneous terpolymers from monomer feed compositions and terminal model reactivity ratios was appended to one of our earlier reviews (.1). 

This program was written to calculate structural features of terpolymers prepared via the following propagation reactions from radicals AA, BA, CA, B and C and from monomers A, B and C. Reactivity ratios utilized by this program are also defined in the following scheme ... 

The conventional [Eq. (7.77)] and simplified [eq. (7.81)] terpolymeriza-tion equations can be used to predict the composition of a terpolymer from the reactivity ratios in the two-component systems M1/M2, M1/M3, and Ms/Ms- The compositions calculated by either of the terpolymerization equations show good agreement with the experimentally observed compositions. Neither equation is found superior to the other in predicting terpolymer compositions. Both equations have been successfully extended to multicomponent copolymerizations of four or more monomers [30,31]. 

Several theoretical treatments of cyclocopolymerization have been reported previously (8-11). These relate the compositions of cyclocopolymers to monomer feed concentrations and appropriate rate constant ratios. To our knowledge, procedures for calculating sequence distributions for either cyclocopolymers or for copolymers derived from them have not been developed previously. In this paper we show that procedures for calculating sequence distributions of terpolymers can be used for this purpose. Most previous studies on styrene-methacrylic anhydride copolymerizations (10,12,13) have shown that a high proportion of the methacrylic anhydride units are cyclized in these polymers. Cyclization constants were determined from monomer feed concentrations and the content of uncyclized methacrylic anhydride units in the copolymers. These studies invoked simplifying assumptions that enabled the conventional copolymer equation to be used in determinations of monomer reactivity ratios for this copolymerization system. 

The terpolymer composition can be predicted on the basis of binary copolymerization experiments. If, however, one (or more) monomer is slow to propagate one of the reactivity ratios will approach zero and eq. 36 will become indeterminate. This situation arises in terpolymerizations involving, for example, MAI I or AMS. Alfrcy and Goldfingcr" derived eq. 37 for the ease w hcrc one monomer (C) is slow to propagate i.e. and hence rc, and ren — 0). 

As discussed above, differences in reactivity ratios can lead to drift in the copolymer composition from that of the starting materials. Noel et al. [39] studied a unique set of monomers, namely VAc, vinyl 2,2-dimethylpropionate and vinyl 2-ethylhexanoate, and determined their reactivity ratios with methyl acrylate. Their work led to the conclusion that the three vinyl esters can be described with one set of reactivity data. This greatly simplifies any potential for compositional drift since only one variable must now be dealt with, namely interphase partitioning of the monomer. Copolymers or terpolymers produced with VAc and vinyl esters have the potential to outperform VAc/acrylic copolymers due to the mote random copolymerization of VAc with other vinyl ester monomers compared with acrylic monomers [40], as is discussed in Section 16.9. 

Terpolymerizadon of la, Ic, and SO2 were carried out to prepare resist polymers by varying the la/lc ratio in the feed. The results are summarized in Table II. The terpolymerization proceeded smoothly, providing the polymer in >90 % yields in 3-4 hrs. Since the terpolymedzations were carried to near completion, the la/lc ratios in the terpolymers are similar to the feed ratios. We suspect that the reactivity ratios of la and Ic are not much different. What is noteworthy is that M and M, become exponentially smaller as the concentration of the fluoroalcohol unit increases in the polymer, pointing to the chain transfer involving the OH group. 

The kinetics for copol5uner and terpolymer systems are obviously more complicated and involve reactivity ratios expressing the tendency for monomer blocking (reaction with the same monomer), or alternate reaction with the different monomers [84]. 

Copolymerization. The importance of VDC as a monomer results from its ability to copolymerize with other vinyl monomers. Its Q value equals 0.22 and its e valne eqnals 0.36. It most easily copolymerizes with acrylates, but it also reacts, more slowly, with other monomers, eg, st5Tene, that form highly resonance-stabilized radicals. Reactivity ratios (ri and T2) with various monomers are listed 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), acrylonitrile (AN), or various alkyl acrylates, but many commercial polymers contain three or more components, of which VDC is the principal one. Usually one component is introduced to improve the processi-bility or solubility of the polymer the others are added to modify specific use properties. Most of these compositions have been described in the patent literature, and a list of various combinations has been compiled (41). A typical terpolymer might contain 90 wt% VDC, with the remainder made up of AN and an acrylate or methacrylate monomer. 

Random, graft, and alternating copolymerization Monomer polymer composition—copolymers Monomer polymer composition—terpolymers Monomer polymer composition—multi-component terpolymers Free radical concentration Reactivity ratios... 

Equations (10.24) and (10.25) were used to simulate the terpolymer composition curves for different termonomer compositions using an MS Office Excel 2007 spreadsheet. The reactivity ratios from Table 10.1 were used. It can be seen that five of the six reactivity ratios are less than 1, and one of them, 23, is greater than 1. The terpolymer composition of AN at two different compositions of AMS in the monomer phase in a CSTR was plotted in Figure 10.5. The curves were found to... 

Multiplicity in termonomer compositions for a given terpolymer composition can be expected at large values of reactivity ratios and compositions. 

Similar to Equations (10.23-10.25), which expresses the terpolymer composition as a function of comonomer compositions and reactivity ratios, develop an expression for comonomer compositions given the terpolymer... 

When one of the reactivity ratios is much larger compared with the other, what can be said about the terpolymer composition ... 

In the terpolymerization composition equation derived for terpolymers and given by Equations (10.23-10.25), what is the significance of equal reactivity ratios such as r 2 = 13 ... 

The chain sequence length distribution of DNA can be represented using the geometric distribution. The mean and variance of the geometric distribution would be expected to depend on the mechanism of formation of polynucleotide sequences. For instance, a terpolymer formed hy free radical polymerization can be modeled with respect to the sequence distribution as follows. Let three termonomers enter a long copolymer chain atMj, M2, and M3 concentrations with reactivity ratios r 2, 21, r23, r 2, 13, 31- Assume that the bond formation order does not matter in the rate, that is,... 

Consider the preparation of styrene-acrylonitrile and methyl methacrylate terpolymer in a CSTR. There can be 3x3 = 9 possible dyads formed. These are AA, AS, SA, SS, SM, MS, AM, MA, and MM. The reactivity ratios can be read from Chapter lO, Table 10.1 The terpolymer composition can be calculated using the terpolymerization composition equations for a CSTR given in Equations (10.23-10.25). The dyad probabilities were calculated using an MS Excel spreadsheet and listed in Table 11.3. Let AN be denoted as monomer 1, styrene as monomer 2, and methyl methacrylate as monomer 3. Assuming that the bond formation order does not influence the rate, that is. 

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