Styrene-maleic anhydride random

Similarly, Jiao also observed the interfacial roughening in a system consisting of polystyrene/benzyl amine end-capped polystyrene/styrene-maleic anhydride random copolymer. He proposed that a microemulsion was formed when the interfacial tension was driven negative by the graft copolymer formed at the interface [72]. 

SMA, styrene-maleic anhydride random copolymer SEBS-MA, maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer OPS, poly(styrene-co-vinyloxa2 lin). 

Lee and Char [93] studied the reinforcement of the interface between an amorphous polyamide (PA) and polystyrene with the addition of thin layers of a random copolymer of styrene-maleic anhydride (with 8% MA) sandwiched at the interface. After annealing above the Tg of PS, they found significantly higher values of Qc for samples prepared with thinner layers of SMA than for the thicker ones. They initially rationalized their results by invoking the competition between the reaction rate at the interface and the diffusion rate of the SMA away from the interface. For very thick layers, and therefore also for pure SMA, the reaction rate was much faster than the diffusion rate away from the interface and favored therefore a multiple stitching architecture, as shown schematically in Fig. 50. Such an interfacial molecular structure does not favor good entanglements with the homopolymer and is mechanically weak. 

However, an active benzene-insoluble methyl methacrylate-maleic anhydride macroradical was obtained when the molar ratio of the maleic anhydride to methyl methacrylate was 4 to 1. This random macroradical contained about 50% maleic anhydride. Excellent yields of block copolymers were obtained when mixtures of maleic anhydride and styrene or vinyl acetate were added to these macroradicals. For example, the ratios of the weight of the styrene-maleic anhydride and the vinyl acetate-maleic anhydride blocks to the weight of the macroradical were 790/100 and 627/100, respectively, after the mixtures of the monomers and the macroradicals were heated in benzene for three days at 50°C. 

Hydrophobic regions can be one or two small, well-defined blocks of pendant hydrophobic moieties in an otherwise water-soluble polymer (2-4). An example is a water-soluble sulfonated BAB triblock copolymer where B is hydrophobic f-butylstyrene and A is vinyltoluene (2). However, hydro-phobic regions can also be less well-defined as well as more numerous in a polymer molecule than is the case for a triblock copolymer (5-22). For example, pendant alkyl esters appear to have been randomly incorporated in styrene-maleic anhydride (5) and vinyl benzyl ether-styrene-maleic anhydride (6-ii) copolymers. Also, alkyl polyoxyethylene acrylate monomers can be copolymerized with acrylamide to yield copolymers with pendant hydrophobic chains (12-15). More recently it was found (16-22) that small amounts of water-insoluble monomers that are solubilized by surfactants into aqueous solutions of a hydrophilic monomer produce copolymers with pendant hydrophobic chains, but the size, number, and nature of the hydro-phobic regions has not been determined. 

Kraton(tm) rubbers are block copolymers of styrene and butadiene. Styrene maleic anhydride copolymer is an alternate copolymer prepared using free radical initiators. Styrene and brominated styrene are copolymerized free radically to produce a random copolymer. 

PS blends (PA6,6 = polyamide 6,6) containing as reactive precursors PS chains end-functionalized with anhydride groups and random functionalized with the same groups, that is, SMA (styrene-maleic anhydride) copolymers. By comparing blends with the same concentration of functionalized PS, it was observed that those containing end-functionalized PS chains presented faster conversion. 

The tendency for alternation of monomers in a styrene-maleic anhydride and styrene-acrylonitrile copolymers at moderate temperatures has been attributed to the formation of a charge transfer complex (CTC) between a donor (D) and an acceptor (A). This CTC is readily detectable by UV or nmR spectroscopy. More important, the equilibrium constant decreases as the temperature is increased and this effect can be followed by instrumental analysis. Thus it is possible to extrapolate to a higher temperature at which the CTC does not exist (16). Thus, by proper temperature control, it is possible to produce SMA alternating copolymers, block copolymers of vinyl monomers with both alternating and random SMA (17) and completely random copolymers of SMA (18). Half esters of SMA have been used as viscosity control agents in petroleum crudes (19). 

Figure 5.5 Bivariate distribution of chain sizes and compositions for sample SH78, high conversion, random styrene maleic anhydride. Reproduced with permission from M.S. Montaudo, Polymer News, 2002,27,115. 2002, Gordon and Breach...

When styrene is copolymerized with maleic anhydride which does not ho-mopolymerize, a completely alternating copolymer is obtained. Maleic anhydride, randomly incorporated into the polystyrene backbone, increases the glass transition temperature and heat distortion temperatures (>260°F). The copolymers are stable during injection molding to temperatures above 550°F [26]. 

The monomers are randomly distributed in the Polymer chain in most of cases but in case of copolymerisation of styrene and maleic anhydride, there is perfect alternate arrangement of monomers in the chain regardless of initial composition of monomers. 

Other commercial copolymers which are typically random are those of vinyl chloride and vinyl acetate (Vinylite), isobutylene and isoprene (butyl rubber), styrene and butadiene (SBR), and acrylonitrile and butadiene (NBR). The accepted nomenclature is illustrated by EP, which is designated poly-ethylene-co-propylene the co designating that the polymer is a copolymer. When the copolymers are arranged in a regular sequence in the chains, i.e., ABAB, the copolymer is called an alternating copolymer. A copolymer consisting of styrene and maleic anhydride (SMA) is a typical alternating copolymer. 

It has been reported that pyrolysis gas chromatographic techniques could be used to differentiate between block and random copolymers (18). However, it was not possible to distinguish between the block copolymers and mixtures of polystyrene and the alternating copolymers of styrene and maleic anhydride by the PGC technique used in this investigation. However, differences were noted in the DTA thermograms of the alternating copolymer, the block copolymer, and the mixture of polystyrene and the alternating copolymer. 

The nomenclature of copolymers includes the names of the monomers separated by the interfix co-. Thus 1-25 would be poly(vinylchloride-co-vinyl acetate). The first monomer name is that of the major component, if there is one. This system applies strictly only to copolymers in which the monomers are arranged more or less randomly. If the comonomers are known to alternate, as in 1-26, the name would be poly(styrene-a//-maleic anhydride). Interfixes may be omitted when the name is frequently used, as in styrene-acrylonitrile copolymers (Section 1.5.3). 

There has been some interest in random copolymers of styrene with small amounts of maleic anhydride. Manufacturers included Monsanto (Cadon), Dow (Resin XP5272) and Dainippon (Ryurex X-15). However, the only current manufacturer of high molecular weight materials appears to be Arco, which markets its products under the trade name Dylarc. The abbreviation SMA is commonly used for these materials. 

In 1930, Wagner-Jauregg described alternating copolymers of styrene and maleic anhydride (J.)- The tendency for regular alternation Instead of a random sequence of styrene and maleic anhydride may be explained by the low reactivity ratio of maleic anhydride (rj) which is approximately 0 and the higher reactivity ratio of styrene ( r2) which is approximately 0.0095 at 25°C (.2). Thus, a value of 0 for the product r r2 is considered as a criterion for alternating copolymers. However, both block copolymers and random copolymers of this system have also... 

PolyCACN) has a rigid chain structure yet can form excimers with alternate units along the chain (8), or by stacking in a helical conformation. Excimer formation has been reported for alternate copolymers of ACN with styrene (9) and for ACN with maleic anhydride CIO). The situation is different for 2-vinylnaphthalene since alternating copolymers of 2VN with methyl methacrylate or methacrylic acid did not form excimers, yet random copolymers of the same systems showed excimer fluorescence Cll). Only random copolymers of ACN were prepared in this work. 

The nomenclature of random copolymers includes the names of the monomers separated by the interfix -co-. Thus (XXII) is named as poly(styrene-co-methyl methacrylate) or poly(methyl methacrylate-co-styrene), depending on which of the monomers is the major component (if there is one). For alternating copolymers, the interfix -alt- is used, e.g., poly(styrene-a/r-maleic anhydride) (XXIII)... 

The UV absorption in the 260 nm region is frequently used to evaluate styrene content in styrene-based polymers (2, 2, 3, 4, 5, 6, 7). Calibration curves for polystyrene solutions are usually based on the assumptions that the UV absorption of the copolymer depends only on the total concentration of phenyl rings, and the same linear relationship between optical density and styrene concentration that is valid for polystyrene holds also for its copolymers. These assumptions are quite often incorrect and have caused sizable errors in the analysis of several statistical copolymers. For example, anomalous patterns of UV spectra are given by random copolymers of styrene and acrylonitrile (8), styrene and butadiene (8), styrene and maleic anhydride (8), and styrene and methyl methacrylate (9, 10, 11). Indeed, the co-monomer unit can exert a marked influence on the position of the band maxima and/or the extinction... 

Glycidyl methacrylate High density polyethylene Isotactic copolymer of styrene and p-methyl styrene Isotactic poly(ethyl methacrylate) Isotactic poly(methyl methacrylate) Isotactic polystyrene Low density polyethylene Linear low density polyethylene Maleic anhydride Poly(4-methyl pentene) Random copolymer of phenyl ether and phenyl ketone... 

Copolymer samples SH91 and SH78 were purchased from MP-DAJAC (Feasterville, PA). They are random copolymer samples of styrene (St) and maleic-anhydride (MAH) obtained at high conversion from solution polymerization using AIBN (N,N -azobisisobutyronitrile) as the initiator. The average molar fraction of St in the copolymer is 0.78 for sanq)le SH78 and 0.91 for sample SH91. 

Influences due to steric hindrance are mostly swamped by those due to polarity and resonance stabilization. For example, 1,2-disubstituted ethylene monomers form random copolymers with comonomers of similar polarity, i.e., dimethyl fumarate/vinyl chloride. If the polarities differ greatly, even alternating copolymers can be formed because of the formation of CT complexes, as, for example, with maleic anhydride/styrene (see also Section 22.3). Even two 1,2-disubstituted monomers copolymerize with each other if the polarities differ very greatly, as happens with, for example, maleic anhydride and stilbene, since the polar interaction in the transition state helps to overcome the steric hindrance. Threefold substituted olefins produce an additional stabilization without steric hindrance in the transition state, and so can be easily copolymerized with comomoners of opposite polarity. 

With Q-e values (20), the reactivity ratios of comonomers, rj and r, can be estimated using Equations 2 and 3. Monomer reactivity ratios can also be determined empirically by carrying out a series of copolymerizations and determining the polymer composition at low conversions. (20b) The reactivity ratios can be used to predict the nature of the copolymer type from a polymerization. For example, when the product of q and r has a value of zero, an alternating copolymer is likely to result from the copolymerization. On the other hand, when the product is near the value of one, the copolymer is likely to be a random copolymer. In a copolymerization process, if one of the comonomers does not homopolymerize, such as in the copolymerization of styrene (rj=0.019) and maleic anhydride (rj=0.0) at 50 °C (20,21), the polymer produced would be an alternating copolymer (Reaction 4). 

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