Styrene-methacrylonitrile

More recently, Dong and Hill [49] used FT infrared (FT-IR) spectroscopy to study copolymer composition and monomer sequence distribution in styrene-methacrylonitrile copolymers. They determined the dependence of the frequencies of the individual spectral peaks on the copolymer composition, in particular, the vibration frequencies for the nitrile group is discussed. Correlations were established to relate changes in the peak positions to changes in the copolymer composition and monomer sequence distribution. Vibration band frequencies for blends of poly(methacrylonitrile) and polystyrene were examined to compare the effects of inter- and intra-chain interactions in these bands. 

At low concentrations of nitrile groups in a styrene-methacrylonitrile copolymer, the frequency of the CN resonance lies in the range 4.484-. 482 pm, depending on 

The increasing vibrational frequency with increasing methacrylonitrile content in the copolymers is consistent with an apparently higher force constant for the CN bond. This can be rationalised in terms of the repulsive forces which exist between the carbon and nitrogen atoms of neighbouring nitrile residues along the polymer chain, and which restrict the vibration of the two atoms in each of the nitrile groups. 

This study does not provide a method of determining the styrene and methacrylonitrile contents of these copolymers, but it does provide important structural information regarding sequence distributions. 

Whereas intensive and C-NMR studies have been pursued for these copolymer systems surprisingly little information is available on another closely related copolymer system, namely styrene-methacrylonitrile copolymer, except for a few H-NMR studies by Harwood and co-workers [162-164], 

Dhal and Steigel [165] carried out a full microstructural analysis of 2,2 -azobisisobutyronitrile initiated random and alternating styrene-methacrylonitrile copolymers by C-NMR. 

For the quaternary carbon atom, unlike a single resonance line observed around 32.5 ppm in the homopolymer spectrum of polymethacrylonitrile, three distinct signals with further finer structures within themselves were observed in the spectra of the copolymers. This is a clear indication of the sensitivity of this carbon atom to comonomer sequence distributions. Assignments of these peaks under three general regions of chemical shifts to different sequential triads were carried out systematically 

After obtaining the sequence distribution information about the methacrylonitrile-centred comonomer triads, Dhal and Steigel [165] proceeded to analyse styrene- 

Serial number Mole fraction of styrene in copolymers Chemical shift of different triads  

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Fig. 3. Oxygen permeabiUties of block (A) and random ( ) styrene—methacrylonitrile (MAN) copolymers [33961 -16-9] (11). See Table 1 for unit...

Styrene markets, 23 345 Styrene - methacrylonitrile copolymers oxygen permeability of block and random, 3 386... 

Hummel et al. (1967) also conducted brief studies of a number of other monomers. Chloroprene behaved simibrly to styrene. Methacrylonitrile behaved somewhat like methyl methacrylate with a definite gel effect. Butyl methacrylate behaved somewhat like styrene but with two small maxima in the rate-conversion curves tbc reasons for this arc unknown but the second small peak could arise from the gel effect. Decyl methacrylate showed only one maximum rate at about 50% conversion. Again the reasons for this behavior are unclear. Isoprene did not polymerize in emulsion at either low or high dose rates. Kaly in et al. (197S) have presented a study of the radiatiorr-induced polymerization of vinyl fiuoride in emulsion. 

This relationship is shown in Figure 13 where Polymer 1 has a permeability 1000 times higher than that of Polymer 2. Published data have small negative deviations from this theoretical relationship. Part of the deviation can be explained by densification of the blend relative to the starting components. Random copolymers, which are forced (by covalent bonds) to imitate combinations of two materials, have permeabilities that are similar to miscible blends. However, the deviations from equation 18 tend to be positive. A series of styrene—methacrylonitrile copolymers were studied (11) and slight positive deviations were found. Figure 14 shows the oxygen permeabilities of a series of vinylidene chloride— -butyl acrylate copolymers [9011-09-0]. 

In CCT a metalloradical reversibly abstracts H from the chain-carrying radical and starts a new chain. Early work on CCT during radical polymerizations employed cobalt porphyrins during the polymerization of methyl methacrylate, and was carried out in the USSR (Smirnov, Marchenko in 1975 Enikolopyan in 1977). Gridnev discovered in Moscow in 1979 that cobaloximes were effective CCT catalysts, then moved to the US in 1992 (Wayland laboratory. University of Pennsylvania) and joined DuPont in 1994. The basic features of CCT have been described in a series of patents (at first Russian, then largely DuPont) that appeared in the 1980s [71], and in a comprehensive review that appeared in 2001 [72]. The mechanism in Scheme 1.8 has become generally accepted, and CCT has been successfully applied to other monomers (styrene, methacrylonitrile) and comonomers. 

Methacrylonitrile-C(3-styrene Methacrylonitrile-co-methyl methacrylate Single Tg Miscibility dependent on compositions of I and II Cowie et al. (1993b)... 

The peak located at -4.48 pm, which is the CN bond stretching band for a styrene— methacrylonitrile copolymer with YM = 0.189, shifts to higher frequency with increasing methacrylonitrile content in the styrene-methacrylonitrile copolymers (Figure 5.7). 

Figure 5.7 Dependence of CN stretching bond at 2229.7 cm i on methacrylonitrile content of styrene-methacrylonitrile copolymers. Reproduced with permission from L. Dong and D.J.T. Hill, Polymer Bulletin, 1995, 34, 323. 1995, Springer...

The a-methyl resonance of styrene-methacrylic acid copolymers [75] (Fig. 11) and of styrene-methacrylonitrile copolymers [27] (Fig. 12) occurs in three separate... 

In order to study the methine resonance patterns of styrene-methacrylonitrile copolymers without interference from methylene proton resonance, a series of... 

Fig. 17. Use of curve simulation to estimate methine proton resonance areas in spectra of a 50/50 styrene-methacrylonitrile copolymer [27]. The upper set of values gives the relative areas of the curves required to reconstruct the resonance pattern. The lower set gives the resonance areas in terms of the proportion of methine resonance observed. Calculated / sm and/i values for this copolymer are 0.730 and 0.249, respectively...

Table 7. Correlation of methine resonance patterns observed for styrene-methacrylonitrile copolymers with calculated styrene centered triad distributions ...

Fig. 20. 100 MHz methine proton resonance pattern of a styrene-methacrylonitrile copolymer prepared in the presence of ZnCl2 [34]...

In an effort to study the methylene resonance of styrene-methacrylonitrile copolymers, several copolymers of a-deuteriostyrene with perdeuteriomethacrylo-nitrile were prepared [55]. Although separate signals were expected from the different types of methylene groups in the copolymers, the spectra obtained (Fig. 21) were broad and poorly resolved, even when recorded at 220 MHz [55]. This disappointing result was probably due to spin-spin interactions between nonequivalent protons in each methylene unit, and to the presence of several possible configurations for each type of diad. On the basis of this result, we do not believe that it is worthwhile to attempt to obtain information about copolymer structure from studies of methylene resonance in copolymers of this type. 

Rubber modifier mold- Styrene Methacrylonitrile W. Germany 2,653,146 1978 Bayer A.G. 

Dong and Hill [129] and Nagata and co-workers [130] used infrared spectroscopy to study the struaure and composition of styrene - methacrylonitrile copolymers. 

Other applications of IR spectroscopy in copolymer characterisation include styrene-glycidyl-p-isopropenylphenyl ether copolymers [4], styrene-isobutylene copolymers [5], vinyl chloride - vinyl acetate - vinyl fluoride terpolymers [6], vinylchloride - vinyl acetate copolymers [7], styrene copolymers [8], ethylene-vinyl acetate copolymers [9], graft copolymers, and butadiene-styrene [10] and acrylonitrile - styrene copolymers [11], polyurethane - polyacrylate [12], polymethylmethacrylate grafted high alpha cellulose [13], bisphenol-polycarbonate (PC) [14], bromobutyl isoprene [15], styrene - methacrylonitrile (SMAN) [16, 17] and styrene - acrylonitrile [18]. 

By carrying out NMR measurements at higher magnetic fields (75 MHz for C-NMR) it became possible to obtain highly resolved resonance lines which can be utilised for structural analysis. Figures 7.19 and 7.20 show, C-NMR spectra of random and alternating styrene-methacrylonitrile copolymers, respectively. 

Table 7.10 Chemical shift assignments of styrene centred comonomer triads from the backbone methane carbon resonance in styrene-methacrylonitrile copolymer. ...

Dong and Hill [167] analysed the FT-IR spectra of a series of random styrene-methacrylonitrile copolymers to determine the dependence of the observed frequencies of the individual spectral peaks on copolymer composition. 

Other acrylonitrile and methacrylonitrile containing copolymers that have been subject to sequencing studies include styrene-methacrylonitrile [165], acrylonitrile... 

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