Monomer reactivity ratios table

A new type of copolymer resist named ESCAP (environmentally stable chemical amplification photoresist) has recently been reported from IBM [163], which is based on a random copolymer of 4-hydroxystyrene with tert-butyl acrylate (TBA) (Fig. 37), which is converted to a copolymer of the hydroxystyrene with acrylic acid through photochemically-induced acid-catalyzed deprotection. The copolymer can be readily synthesized by direct radical copolymerization of 4-hydroxystyrene with tert-butyl acrylate or alternatively by radical copolymerization of 4-acetoxystyrene with the acrylate followed by selective hydrolysis of the acetate group with ammonium hydroxide. The copolymerization behavior as a function of conversion has been simulated for the both systems based on experimentally determined monomer reactivity ratios (Table 1) [164]. In comparison with the above-mentioned partially protected PHOST systems, this copolymer does not undergo thermal deprotection up to 180 °C. Furthermore, as mentioned earlier, the conversion of the terf-butyl ester to carboxylic acid provides an extremely fast dissolution rate in the exposed regions and a large... 

Conversions increased with time, in all four cases, and the monomer reactivity ratios (Table 10.3) decreased through the series. The low molecular weight of all four copolymers, as shown by intrinsic viscosity values, remained almost constant and independent of conversion. The constant production of only low-molecular-weight copolymer is probably achieved by very pronounced chain transfer to monomer or to CTC and low concentration of CTC during the course of the reaction. 

Finally where both reactivity ratios take the value of zero, the monomers do not react at all, with growing polymer chains terminated in their own kind of monomer unit. This results in alternating copolymerisation. A few typical monomer reactivity ratios are given in Table 2.2. 

Table 2.2 Typical monomer reactivity ratios (reaction temperature 60 °C in each case)...

Table XXII.—Monomer Reactivity Ratio Products (50 to 80°) (From Mayo and Walling )... 

We also investigated the copolymerizations of 1-hexene with 4-methyl-l-hexene and of 4-methyl-l-hexene with 5-methyl-l-hexene by the aforementioned techniques (33). The monomer reactivity ratios for these two pairs are shown in Table VII. 

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

The monomer reactivity ratios for many of the most common monomers in radical copolymerization are shown in Table 6-2. These data are useful for a study of the relation between structure and reactivity in radical addition reactions. The reactivity of a monomer toward a radical depends on the reactivities of both the monomer and the radical. The relative reactivities of monomers and their corresponding radicals can be obtained from an analysis of the monomer reactivity ratios [Walling, 1957]. The reactivity of a monomer can be seen by considering the inverse of the monomer reactivity ratio (1 jf). The inverse of the monomer reactivity ratio gives the ratio of the rate of reaction of a radical with another monomer to its rate of reaction with its own monomer... 

TABLE 6-2 Monomer Reactivity Ratios in Radical Copolymerization ... 

Table 6-8 shows values of the various parameters needed to calculate monomer reactivity ratios from Eqs. 6-60 and 6-62 [Jenkins and Jenkins, 1999]. The monomers in Table 6-8 are lined up in order of their u values. The Patterns of Reactivity scheme, like the Q e. scheme, is an empirical scheme. Monomer reactivity ratios calculated by the patterns of reactivity scheme are generally closer to experimental values than those calculated by the Q e scheme, which supports the rationale of assigning different polarity values to a monomer and the radical derived from the monomer. 

It has previously been shown that large changes can occur in the rate of a cationic polymerization by using a different solvent and/or different counterion (Sec. 5-2f). The monomer reactivity ratios are also affected by changes in the solvent or counterion. The effects are often complex and difficult to predict since changes in solvent or counterion often result in alterations in the relative amounts of the different types of propagating centers (free ion, ion pair, covalent), each of which may be differently affected by solvent. As many systems do not show an effect as do show an effect of solvent or counterion on r values [Kennedy and Marechal, 1983]. The dramatic effect that solvents can have on monomer reactivity ratios is illustrated by the data in Table 6-10 for isobutylene-p-chlorostyrene. The aluminum bromide-initiated copolymerization shows r — 1.01, r2 = 1.02 in n-hexane but... 

Monomer reactivity ratios and copolymer compositions in many anionic copolymerizations are altered by changes in the solvent or counterion. Table 6-12 shows data for styrene-isoprene copolymerization at 25°C by n-butyl lithium [Kelley and Tobolsky, 1959]. As in the case of cationic copolymerization, the effects of solvent and counterion cannot be considered independently of each other. For the tightly bound lithium counterion, there are large effects due to the solvent. In poor solvents the copolymer is rich in the less reactive (based on relative rates of homopolymerization) isoprene because isoprene is preferentially complexed by lithium ion. (The complexing of 1,3-dienes with lithium ion is discussed further in Sec. 8-6b). In good solvents preferential solvation by monomer is much less important and the inherent greater reactivity of styrene exerts itself. The quantitative effect of solvent on copolymer composition is less for the more loosely bound sodium counterion. 

Using the Q and e values in Table 6-7, calculate the monomer reactivity ratios for the comonomer pairs styrene-1,3-butadiene and styrene-methyl methacrylate. Compare the results with the r and rx values in Table 6.2. 

Calculate the monomer reactivity ratios for chloroprene-2-vinylpyridine using the data from Table 6-8 for the patterns of reactivity scheme. 

Statistical copolymerization occurs among ethylene and various a-olefins [Baldwin and Ver Strate, 1972 Cooper, 1976 Pasquon et al., 1967 Randall, 1978]. The reactivities of monomers in copolymerization generally parallel their homopolymerization behavior ethylene > propene > 1-butene > 1-hexene [Soga et al., 1989]. Table 8-7 shows monomer reactivity ratios for several comonomer pairs. 

If we define the monomer reactivity ratio for monomer 1 and 2, ri and ri, respectively, as the ratio of rate constants for a given radical adding to its own monomer to the rate constant for it adding to the other monomer (ri = fcn/ 12 and ri = 22/ 21 see Table 3.7 for typical values), then we arrive at the following relationship known as the copolymer equation ... 

Table 3.7 Typical Monomer Reactivity Ratios in the Addition Polymerization of Copolymers...

In THF, however, no difference in the monomer reactivity ratios was observed between the (S)-MBMA-TrMA and (RS)-MBMA-TrMA systems, and the ratios (r =0.39 and 2- . ) showed similar reactivity of MBMA (Mi) and TrMA ( 2). The copolymerization seemed to proceed without termination and chain transfer reactions. An abnormal optical property was observed in some of the copolymers of (S)-MBMA and TrMA. Table shows the tacticity and optical data of the copolymers which were obtained in various polymer yields from the monomer mixtures of a constant molar ratio, [Mllo/[M2]o = The (S)-MBMA content in the copolymers decreased... 

The NMR analysis (21) of the chemical composition for copolymers from various monomer feed ratios at fairly low conversion are shown in Table IV. The results were then used to estimate the reactivity ratios for the diene monomers under the conditions employed. Various published methods of calculating monomer reactivity ratios have been examined. These include the once popular but now somewhat out of favor Fineman-Ross method... 

Table 10.2 Monomer Reactivity Ratios for Styrene Acrylonitrile (5)...

Table 2. Monomer reactivity ratios of styrene and indene" ...

THF copolymerizes readily with other cyclic ethers such as oxides and oxetanes. The comonomers used include ethylene oxide (67), propylene oxide (99,100), epichlorohydrin (ECH) (101,102), phenyl glycidyl ether (102), 3.3-bis(chloromethyl) oxetane (BCMO) (25, 98, 101, 103) and 3-methyl-3-chloromethyl oxetane (103). Just as in THF homo-polymerization, a large variety of catalysts have veen used. In many cases the kinetics of copolymerization have been studied. Table 22 summarizes the monomer reactivity ratios, rx (THF), and r2 (comonomer) which have... 

Extensive tables of so-called monomer reactivity ratios are available and make it possible to predict the compositions of copolymers formed from particular mixtures of monomers. 

Labelled monomers have been used in co-polymerizations for analysis of the resulting co-polymers and consequent determination of monomer reactivity ratios (15, 16). This technique is of particular value when the compositions of the different monomer units are rather similar or when the co-polymer contains only very small amounts of one of the monomers. These points can be appreciated by considering calculations on co-polymers of methyl methacrylate and methyl acrylate summarized in Table 1. The analyses have been calculated ignoring contributions of end-groups it assumed that the acrylate ester is labelled with carbon-14 and that specific activities are expressed in units such as curies/g of carbon. 

From the Finemann-Ross plot of the data in Table II, monomer reactivity ratios are determined. riK = 0.654, r2/K = 1.09. The copolymer composition diagram is shown in Figure 3, which includes both spontaneous and catalytic polymerization to prove the similarity of both mechanisms. 

The relative monomer reactivity ratios, r and r2, for ethylene/cycloolefin copolymerisation with zirconocene-methylaluminoxane catalysts are presented in Table 3.6 [468],... 

Table III shows the increase of molecular weight of BCMO polymerization with conversion, although the polymer tends to precipitate. The monomer reactivity ratios of DOL-BCMO copolymerization were previously determined as rx (DOL) = 0.65 0.05, r2 (BCMO) = 1.5 0.1 at 0°C. by BF3 Et20 (8). Table IV shows a preparation of block copolymer of DOL, St, and BCMO. In the first step we polymerized DOL and St in the second step we added BCMO to this living system. The copolymer obtained showed an increase of molecular weight, and considerable BCMO was incorporated in the copolymer still remaining soluble in ethylene dichloride. The solubility behavior together with the increase of molecular weight with addition of BCMO shows that this polymer consists of block sequences of DOL-St and (St)-DOL-BCMO. This we call block and random copolymer of DOL-St—BCMO. We can deny the presence of BCMO, St, or DOL homopolymers in this system, but some chain-breaking reactions are unavoidable, leading to copolymer mixtures. Thus, the principle of formation of block copolymers by cationic system is partly substantiated.

The monomer reactivity ratios could be calculated from Table A and other values by the method of Fineman and Ross (10), but owing to the narrow range of compositions studied only the value of r2 (referring to the styrene radical) was significant. A value of 0.7 was obtained which may be compared with 0.52 for styrene-methyl methacrylate, and a value of 0.41 calculated from the Q — e values for hydroxyethyl methacrylate supplied by Rohm and Haas (25). 

From the values of the monomer reactivity ratios, the relative reactivity of the monomers toward the growing free radicals derived from MAOThe, MAOA and MAOU (t, a and u, respectively) was estimated (Table 6). As for the growing radical of MAOThe (t), for example, the reactivities of MAOThe and MAOU monomer are equal but higher than that of MAOA monomer in ethanol solution while the reactivities of these monomers are nearly equal in dioxane solution. The copolymerization proceeds predominantly under the influence of base-base pairing between adenine and uracil rings. 

Table 8 shows the monomer reactivity ratios for the copolymerization. In the case of copolymerization of MAOT (Mi) with MAOA (M2) in chloroform solution, the rl5 r2 and rtr2 values obtained are much smaller than unity, and thus the copolymerization tends to be alternating, similar to that of MAOA with MAOU in dioxane solution. On the other hand, in the copolymerizations of MAOA (Mi) with 9-(P-methacryIoyl-oxyethyl)carbazole (MAOCz) (M2) and MAOT (Mi) with MAOCz (M2), rt values are larger than r2 values, and rir2 values suggest that these copolymerizations tend to... 

On the basis of their reactivity ratios (Table f 6-5 below), predict what types of microstruc- i tures (e.g., tendency to alternating, tendency to blocky) you would expect in a free radical copolymerization of the following monomer pairs ... 

Plotting jc(l - n)/n versus x ln will give a straight line with a slope of -ri and an intercept of r2- The monomer reactivity ratios for some common monomers in radical copolymerization are listed in Table 14.25. 

An examination of reported reactivity ratios (Table 6) shows that the behaviour rj > 1, r2 1 or vice versa is a common feature of anionic copolymerization. Only in copolymerizations involving the monomers 1,1-diphenylethylene and stilbene, which cannot homopolymerize, do we find <1, r2 <1 [212—215], and hence the alternating tendency so characteristic of many free radical initiated copolymerizations. Normally one monomer is much more reactive to either type of active centre in the order acrylonitrile > methylmethacrylate > styrene > butadiene > isoprene. This is the order of electron affinities of the monomers as measured polarographically in polar solvents [216, 217]. In other words, the reactivity correlates well with the overall thermodynamic stability of the product. Variations of reactivity ratio occur with different solvents and counter-ions but the gross order is predictable. 

Monomer reactivity ratios for copolymerization of the itaconates with other monomers are listed in Table 4. Solvent and pH changes which... 

Reactivity of itaconic add in copolymerization is dependent upon pH and degrees of ionization of the add. Acid reactivity has been studied most carefully in acrylonitrile copolymerization 33, 37). Under acidic conditions an increase in itaconic concentration greatly decreases the polymerization rate, while at pH s of 7—9.8 moderate increases of itaconate do not reduce the rates so strongly. Monomer reactivity ratios and Q and e values have been calculated for the various states of ionization of the acid as reported in Table 5. As the pH rises, drops from 1.57 to 0.1 suggesting, as stated earlier, that the dianion undergoes little homopolymerization. The change in is less than 2-fold which indicates appreciable copolymerization of the dianion. The much greater decrease... 

Table II. Effect of Pressure on Monomer Reactivity Ratios...

Some data recently obtained on high pressure ethylene copolymerizations illustrate the quantitative aspects of an ethylene-based Q-e scheme (6). In Figures 3 and 4 copolymer composition curves for the ethylene-vinyl chloride and the ethylene-vinyl acetate copolymerizations are given. The monomer reactivity ratios for these two systems are tabulated in Table III along with Q values and e values for vinyl chloride and vinyl acetate calculated using ethylene as the standard (Q = 1.0 and g = 0). These Q and e values may be compared with those obtained using styrene as the standard. 

Ethylene is used in a considerable number of copolymers. Some of these are binary copolymers, but copolymers of three or even four components also are known. As indicated in Section 2.3, specific monomer reactivity ratios are required for generating a copolymer. However, this requirement is satisfied for a number of monomers. Some common copolymers of polyethylene are indicated in Table 6.1.3. Some of the copolymers listed in Table 6.1.3 are a/f-copolymers. They behave during pyrolysis as homopolymers. More details regarding pyrolysis of several a/f-copolymers are given further in this section for poly(propylene-a/f-ethylene), in Section 6.3 for poly(ethylene-a/f-chlorotrifiuoroethylene), and in Section 6.9 for poly(ethylene-a/f-maleic anhydride). The copolymers in which the backbone chain contains atoms different from carbon, such as oxygen or sulfur, are discussed in sections dedicated to polymers containing that particular atom in the backbone. 

The monomer reactivity ratios rj (=/fii//ci2) and r2 (= 22/ 21) (Table 2.3) reflect the relative rate constants for a given radical adding to its precursor monomer and to the alternative. If the monomers are very similar for example two slightly different acrylates then the values of ri and ro are close to equal and unity. In such a case, the composition of the polymer is equal to the composition of the feedstock at all stages of the polymerization. If on the other hand, the values are both small as in the case of maleic anhydride and styrene then each monomer is reluctant to react with itself the result is an alternating copolymer. 

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