Styrene with Maleic Anhydride

Many styrene-maleic anhydride copolymers are produced commercially for special uses. These are formed by free-radical copolymerization and many commercial grades are partially esterified. Molecular weights of such polymers may range from 1500-50,000, depending upon the source. The 

Only a small percent of styrene copolymers reported in the literature achieved industrial importance. Some of the interesting copolymers of styrene that were reported but not utilized commercially are copolymers with various unsaturated nitriles. This includes vinvlidine cyanide, fumaronitrile, malononitrile, methacrylonitrile, acrylonitrile, and cinnamonitrile. Often, copolymerization of styrene with nitriles yields copolymers with higher heat distortion temperature, higher tensiles, better craze resistance, and higher percent elongation. 

Styrene was also copolymerized with many aciylic and methacrylic esters. Products with better weatherability often form. Copolymerizadon with some acrylates lowers the value of Tg  

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Figure 15.3 illustrates that the free radical polymerization of PMI and styrene proceeds in an alternating manner [22,29,30]. Over a wide range of monomer ratio, the copolymerization (at low conversions) results in polymers with PMI content between 45 and 55 % and a Tg between 225 and 245 °C. The same type of alternation is observed in the copolymerization of styrene with maleic anhydride [31] and various A-alkyl-substituted maleimides [32-35]. It is... 

The laser-initiated polymerization of styrene with maleic anhydride has been said to occur through either a singlet or triplet excimer (the authors surely mean exciplex ) of the anhydride as shown in Scheme 4. This study provides an interesting comparison between laser- and u.v.-initiated polymerization, and Table 2 shows clearly that the former is a very energy-efficient system. In the laser-initiated polymerization of a thiol-ene system, oxygen inhibition was not a significant problem and similar conclusions were reached on the energy efficiency of lasers. On a related note, the efficiency of the well-known benzo-phenone-triethylamine complex is apparently enhanced if carboxylic acids are added to the system. ... 

Recent studies in our laboratory were aimed at defining more closely the conditions governing Intramolecular excimer formation in dilute polymer solutions (15). An alternating copolymer of styrene with maleic anhydride or methylmethacrylate showed no excimer emission, confirming that interactions of other than neighboring phenyl residues made no significant contribution to... 

Various compatibilizing agents have been used to assist in the toughening of polyamides by core-shell particles Qontaining PMMA shells they include copolymers of styrene with maleic anhydride [150] and with acrylic acid [151]. Good particle dispersions and interfaces are achieved because the copolymers are miscible with the PMMA shells of the particles and react with the polyamide matrix. Blends of polyamides with ABS have been extensively studied, with copolymers of styrene and maleic anhydride again used as compatibilizers [152-156]. 

Copolymers of styrene with maleic anhydride, 165, 271 Dyneon HTE Fluoropolymer, 381 Ebecryl (Series)... 

Styrene Maleic Anhydride Copolymer Thermoplastic copolymer of styrene with maleic anhydride. Has good thermal stability and adhesion, but decreased chemical and light resistance. Processed by injection and foam molding and extrusion. Used in auto parts, appliances, door panels, pumps, and business machines. Also called SMA. 

Alternating copolymerization of styrene with maleic anhydride is also explained by donor... 

In fact, recent theoreticaP and experimental studies of small radical addition reactions indicate that charge separation does occur in the transition state when highly electrophilic and nucleophilic species are involved. It is also known that copolymerization of electron donor-acceptor monomer pairs are solvent sensitive, although this solvent effect has in the past been attributed to other causes, such as a Bootstrap effect (see Section 13.2.3.4). Examples of this type include the copolymerization of styrene with maleic anhydride and with acrylonitrile. Hence, in these systems, the variation in reactivity ratios with the solvent may (at least in part) be caused by the variation of the polarity of the solvent. In any case, this type of solvent effect cannot be discounted, and should thus be considered when analyzing the copolymerization data of systems involving strongly electrophilic and nucleophilic monomer pairs. 

Versions of the Bootstrap model have also been fitted to systems in which monomer-monomer complexes are known to be present, demonstrating that die Bootstrap model may provide an alternative to the MCP and MCD models in these systems. For instance, Klumperman and co-workers have successfully fitted versions of the penultimate Bootstrap model to the systems styrene with maleic anhydride in butanone and toluene, and styrene... 

Example 3.38 Radical Copolymerization of Styrene with Maleic Anhydride (Aiternating Copolymerization)... 

The copolymerization of styrene with maleic anhydride creates with a copolymer (SMA) which has a higher glass transition temperature than polystyrene and is chemically reactive with certain functional groups. Thus, SMA polymers are often used in blends or composites where interaction or reaction of the maleic anhydride provides for desirable interfacial effects. The anhydride reaction with primary amines is particularly potent. 

It was reported by Barb in 1953 that solvents can affect the rates of copolymerization and the composition of the copolymer in copolymerizations of styrene with maleic anhydride [145]. Later, Klumperman also observed similar solvent effects [145]. This was reviewed by Coote and coworkers [145]. A number of complexation models were proposed to describe copolymerizations of styrene and maleic anhydride and styrene with acrylonitrile. There were explanations offered for deviation from the terminal model that assumes that radical reactivity only depends on the terminal unit of the growing chain. Thus, Harwood proposed the bootstrap model based upon the study of styrene copolymerized with MAA, acrylic acid, and acrylamide [146]. It was hypothesized that solvent does not modify the inherent reactivity of the growing radical, but affects the monomer partitioning such that the concentrations of the two monomers at the reactive site (and thus their ratio) differ from that in bulk. 

Alternating copolymerization of styrene with maleic anhydride is also explained by donor acceptor interactions [171]. A charge-transfer complex is seen as the new monomer, a diradical, which polymerizes through coupling [171-174]. 

Whether the concept of charge-transfer complexes in copolymerizations is fully accepted is not certain. Much of the accumulated evidence, to date, such as UV and NMR spectroscopy, does support it in many systems [195]. Further support comes from the strong tendencies to form alternating copolymers over a wide range of feed compositions, and also from high reaction rates at equimolar feed compositions [171]. On the other hand, as shown above, it was claimed in the past that copolymerization of styrene with maleic anhydride involves charge-transfer complexes [171, 181-183]. This, however, is now contradicted in a publication of a study of radical copolymerization of maleic acid with styrene. The reaction was carried out in a dioxane solution at 70 C. The authors reported that UV spectroscopy fails to show presence of a charge transfer and formation of a complex between the two monomers in the copolymerization system [196]. 

This mechanism has been extended to the spontaneous copolymerizations of styrene with maleic anhydride and other electron-acceptor monomers (see Scheme 1, Several authors have studied the spontaneous polymerization of st5rene with acrylonitrile focusing on isolated trimers that are produced presumably as a result of the initiation step however, the trimer structures do not suffice to differentiate between the Mayo mechanism and the Flory diradical mechanism. 

We provide here experimental evidence about the faster rate of spontaneous radical generation of styrene with maleic anhydride than that present in the spontaneous... 

Studies have also been performed on copolymers of styrene with maleic anhydride (SMA-n) 22 containing n wt % maleic anhydride. 

Synthesis of the spin-labelled copolymer of styrene with maleic anhydride has been carried out on heating a solution of the copolymer and radical IV (R=NH2) in... 

Copolymerization of styrene with maleic anhydride yields alternating structures, probably due to the formation of charge transfer complexes [126,127]. Statistical copolymers... 

WU 03] Wu D C., Hong C.Y., Pan C.Y. et al, Study on controlled radical alternating copolymerization of styrene with maleic anhydride trader UV... 

Copolymers of styrene with acrylonitrile (SAN) and styrene with maleic anhydride (SMA) are typical examples of uniform alternating copolymers. 

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