Copolymerization of styrene and maleic anhydride

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. ... 

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. 

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). 

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). 

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

Chlorine is virtually absent in the copolymer produced in the azobisisobutyronitrile (AIBN) catalyzed copolymerization of styrene and maleic anhydride in the presence of chloroform or carbon tetrachloride (3, 4), or of p-dioxene and maleic anhydride in the presence of acrylonitrile in chloroform (5). This absence indicates that trichloromethyl radicals generated by the reaction of the chlorinated hydrocarbons with the radicals from AIBN are not incorporated into the polymer chain. Similarly, there is little or no cnlorine in the alternating copolymer that is formed in the copolymerization of styrene and methyl methacrylate in the presence of ethylaluminum sesquichloride (EASC) in the presence of chloroform and carbon tetrachloride, and with or without a peroxide initiator (6). 

The failure to incorporate moieties arising from radical attack on the solvent into the alternating copolymers, coupled with the virtual absence of catalyst residues in the copolymer when the copolymerization of styrene and maleic anhydride is initiated by AIBN (3, 4), indicates that radical species may initiate the polymerization of comonomer charge-transfer complexes, but they are not incorporated into the polymer chain. 

Spontaneous copolymerization of styrene and maleic anhydride in the presence of a molten polymer or a bulk polymer undergoing deformation at elevated temperatures is a rapid and convenient route for carboxylating polymers. The reaction is carried out on the bulk polymer at 120° to 200°C. (depending upon the softening or melting point of the polymer) by injecting an equimolar solution of maleic anhydride in styrene into the molten polymer (II, 12). 

Radical-catalyzed graft copolymerization is generally accompanied by crosslinking or scission (or both) of the substrate polymer. Gel permeation chromatographic analysis of polymer carboxylated by the in situ copolymerization of styrene and maleic anhydride without a radical catalyst shows that the molecular size distribution of the carboxylated... 

This is presumably what occurs in the copolymerization of styrene and maleic anhydride. The proposed structure is indicated below ... 

Klumperman, B. Free Radical Copolymerization of Styrene and Maleic Anhydride, PhD Thesis,... 

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. 

Brouwer, H. De, Schellekens, M. A. Klumperman, B., Monteiro, M. J., and German, A. L. 2000. Controlled radical copolymerization of styrene and maleic anhydride and the synthesis of novel polyolefin-based block copolymers by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Journal of Polymer Science, Part A Polymer Chemistry 38 3596-3603. 

In this communication we give preliminary results aimed at the elucidation of the mechanism and the estimation of the rate of radical generation in the spontaneous copolymerization of styrene and maleic anhydride. First, we show experiments that give order-of-magnitude estimates of the rate of radical generation in the copolymerization system, as compared with the homopolymerization of styrene. Second, we show additional results that give a preliminary estimation of the corresponding kinetic rate constant under some... 

For further insight into the initialization process, the focus is shifted to a copolymerization system. The copolymerization of styrene and maleic anhydride (MAh) was investigated using CDB and CiPDB as the RAFT-agents. This provides an excellent opportunity to investigate the effect of an electron-deficient comonomer on the initialization behavior of styrene as an electron-rich monomer. As indicated above, under certain conditions, the initialization time for the CiPDB-mediated polymerization of styrene is approximately 40 minutes. An experiment was conducted under comparable conditions, where styrene is now replaced by a 1 1 [mol] mixture of styrene and maleic anhydride. Despite... 

Figure 5 shows the concentration profiles of the relevant species in the CDB-mediated copolymerization of styrene and maleic anhydride. This experiment was conducted at 70 °C, in the same fashion as the previously discussed experiments. The initialization in this experiment was extremely fast in comparison to the homopolymerization of styrene. Where the initialization period for a CDB-mediated styrene homopolymerization was 240 min-... 

Relative concentrations of relevant species as a function of time determined via in s/tu H-NMR spectroscopy during the CiPDB-mediated copolymerization of styrene and maleic anhydride at 70 °C. [STY] [MAh] [CiPDB] [AIBN] =4,13.8 1 0.20 [mol]. ... 

From an economic point of view, the other copolymers of styrene are much less important than those above. Copolymerization with a-methylstyrene leads to an increase in the glass transition temperature of the corresponding polymer. Copolymerization with acrylic esters allows the generation of polar sites along the nonpolar polystyrene chains (ionomers and others). Almost perfectly alternating copolymers can be obtained by copolymerization of styrene and maleic anhydride by a radical process. 

HiU DJT, O Donnell JH, O SuUivan PW. Analysis of the mechanism of copolymerization of styrene and maleic anhydride. Macromolecules. 1985 18 9-17. 

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