Styrene and maleic anhydride

Some characteristics of free-radical terpolymerization of tri-butylstannyl methacrylate, styrene and maleic anhydride governed by the pentacoordination state of the tin atom are reported in Refs. 95),96). It is shown that a coordination-bound monomer has a considerable effect on chain initiation and propagation. Copolymerization mainly involves the participation of complex-bound monomers. 

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. 

The copolymerization of styrene and maleic anhydride was studied by the spintrapping technique using 2-methyl-2-nitrosopropane as a spin trap. Four types of ESR spectra were obtained, of which three corresponded to trapping of the growing polymer chain at a centre originating from the styrene part or from two centres originating from the maieic anhydride part. The fourth EPR spectrum may be due to a cyclic flve-membered aminoxyl or a six-membered 1,2-oxazine radical cation. ... 

The 1 1 copolymer so obtained has alternating monomeric units of styrene and maleic anhydride.This can be verified by NMR spectroscopy.lt is insoluble in carbon tetrachloride, chloroform, toluene, and methanol, but soluble inTHF,1,4-dioxane,and DMF.lt can be hydrolyzed to a polymeric acid (see Example 5-3)... 

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. 

STYRENE-MALEIC ANHYDRIDE. A thermoplastic copolymer made by the copolymerization of styrene and maleic anhydride. Two types of polymers are available—impact-modified SMA terpolymer alloys (Cadon ) and SMA copolymers, with and without rubber impact modifiers (Dylark ). These products are distinguished by higher heat resistance than the parent styrenic and ABS families. The MA functionality also provides improved adhesion to glass fiber reinforcement systems. Recent developments include lerpolymer alloy systems with high-speed impact performance and low-temperature ductile fail characteristics required by automotive instrument panel usage. 

Thus, it is possible to provide homogeneous solution polymerization systems providing the solubility parameters of the monomer, polymer, and solvent are known. Styrene and maleic anhydride were copolymerized by both techniques in the experiments described in this report. 

As shown in Figure 2, the rate of the heterogeneous copolymerization of styrene and maleic anhydride in benzene (8 = 9.2) is faster than the homogeneous copolymerization of these monomers in acetone (8 = 9.9). However, this rate decreases as the solubility parameter values of the solvents decrease in heterogeneous systems. Thus, the rate of copolymerization decreases progressively in xylene (8 = 8.8), cumene (8 = 8.5), methyl isobutyl ketone (8 = 8.4), and p-cymene (8 — 8.2). All of these rates were faster than those observed in homogeneous systems. The solubility parameter of the alternating styrene-maleic anhydride copolymer was 8 = 11.0. 

Attempts to change the copolymerization of styrene and maleic anhydride in benzene from a heterogeneous to a homogeneous process by using high concentrations of initiator or by adding weak chain transfer agents, such as carbon tetrachloride, were unsuccessful. However, homo-... 

The only product obtained by the copolymerization of styrene and maleic anhydride in acetone was the alternating copolymer even in the presence of more than equimolar quantities of either styrene or maleic anhydride. However, as shown by the data in Table I, larger quantities were obtained than could be accounted for by the formation of the alternating copolymer when excess styrene was used for the copolymerization in benzene solutions. In addition to the precipitates, there was also a trace of benzene-soluble product, which was shown to be polystyrene by infrared spectrometric (28) and pyrolytic gas chromatographic techniques (26). 

Table I. Yields of Copolymers of Styrene and Maleic Anhydride Obtained by Heterogeneous Copolymerization in Benzene after 72 Hours at 50°C...

Table II. Relationship of the Ratio of Areas under a Styrene Peak to the Reference Peak in the Gas Chromatograms of the Pyrolytic Products Obtained from Copolymers of Styrene and Maleic Anhydride in Benzene...

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. 

No product was obtained when attempts were made to copolymerize styrene and maleic anhydride in benzene at 50° C in the absence of bis-azoisobutyronitrile. Likewise, no free radicals were detectable when these solutions were examined using EPR techniques. Negative results were also noted in solutions of the alternating copolymer prepared in acetone. However, the presence of free radicals was noted when the alternating copolymer produced by heterogeneous solution polymerization in benzene was examined. This peak was observed with freshly prepared and aged copolymer samples that had been stored in an inert environment. However, no peak was observed in product that had been washed with methanol. 

Macroradicals obtained by the copolymerization of equimolar quantities of styrene and maleic anhydride in benzene or in cumene were also used as initiators to produce block copolymers with methyl methacrylate, ethyl methacrylate, and methyl acrylate. The yields of these block copolymers were less than those obtained with styrene, but as much as 38% of methyl methacrylate present in the benzene solution added to the macroradical to produce a block copolymer. The amount of ethyl methacrylate and methyl acrylate that was abstracted from the solution to form block copolymers was 35 and 20%. 

Macroradicals obtained by the heterogeneous copolymerization of styrene and maleic anhydride in poor solvents such as benzene were used to initiate further polymerization of selected monomers. This technique was used to produce higher molecular weight alternating copolymers of styrene and maleic anhydride and block copolymers. Evidence for the block copolymers was based op molecular weight increase, solubility, differential thermal analysis, pyrolytic gas chromatography, and infrared spectroscopy. 

In contrast to the radical-monomer interaction in the transition state proposed by Mayo and Walling (62, 63), the formation of a molecular complex between the electron donor monomer and the electron acceptor monomer—i.e., monomer-monomer interaction—has been proposed as the contributing factor in the free radical alternating copolymerization of styrene and maleic anhydride (8) as well as sulfur dioxide and mono-or diolefins (6, 9, 12, 13, 25, 41, 42, 43, 44, 61, 79, 80, 88). Walling and co-workers (83, 84) did note a relationship between the tendency to form molecular complexes and the alternating tendency and considered the possibility that alternation involved the attack of a radical on a molecular complex. However, it was the presence in the transition state of polar resonance forms resembling those in the colored molecular complexes which led to alternation in copolymerization (84). 

In our work on copolymerizations involving charge transfer intermediates, it has been noted that when a mixture of styrene and maleic anhydride is heated to 80 °C. in the presence of benzoyl peroxide, an extremely exothermic reaction occurs, and in a sealed system the temperature rises from 80° to 250°C. within three minutes, and the conversion is quantitative. 

The sodium salt of polyacrylic acid is also an effective antiredeposition polymer. Molecular weights of 5000 gm/mole give a good combination of performance-handling characteristics. Co-polymer of styrene and maleic anhydride are also commonly used, although the optimum molecular weight is approximately 45,000. The polyacrylates are typically used at 0.5-1 percent in the formulation. 

Maleic anhydride is an important intermediate in the chemical industry [8-9]. It is used in polycondensation and addition reactions. The end products of these reactions are polyesters, alkyd resins, lacquers, plasticizers, copolymers and lubricants. For example, the copolymer of styrene and maleic anhydride is an engineering plastic. 

Thus a statistical copolymer of ethylene and propyiene is named poly(ethylene-stef-propylene), and an ABA tri-block copolymer of styrene (A) and isoprene (B) is named polystyrene-block-polyisoprene-block-polystyrene. In certain cases, additional square brackets are required. For example, an alternating, copolymer of styrene and maleic anhydride is named poly[styrene-d/f-(maleic anhydride)]. 

The method described here was used for determination of conformational state and distance between polymer chain ends of various spin-marked polymers. poly-4-vinylpyridine (PVP ), polymethacrylic acid (PMAA ), sodium salt of polymethacrylic acid (PMAA -Na), styrene and maleic anhydride copolymer (STMAL ) [9, 10, 13] (formulas of spin-marked macromolecules are presented in Scheme 1 molecular masses of polymers and used solvents are presented in Table 1). 

Sanayei RA, O Driscoll KF, Klumperman B (1994) Pulsed laser copolymerization of styrene and maleic anhydride. Macromolecules 27(20) 5577-5582... 

The First styrene copolymer was reported in 1930 by Wagner-Juaregg and was a copolymer of styrene and maleic anhydride [26]. This copolymer (SMA), which was called a heteropolymer by its inventor, has excellent resistance to continuous exposure in boiling water. 

Figure 5. Evolution of conversion with time for the polymerization of a 9 1 mixture of styrene and maleic anhydride mediated by 42 and 0.05 equiv of 17 at 123 °C.

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