STYRENE-METHACRYLIC ACID COPOLYMER

Lecourtier, J. Lafuma, F. Quivoron, C., "Study of Polymer Compatibilization in Solution through Polymer/ Polymer Interactions Ternary Systems Polyethylene oxide)/ Styrene-Methacrylic Acid Copolymers/Solvent," Makromol. Chem., 183,2021 (1982). 

Figure 9.16. Tan 5 vs. temperature for styrene-methacrylic acid copolymer Ii lied with glass beads of different diameter. [Data from Bergeret A, Alberola N, Polymer, 31, No.13, 1996, 2759-65.]...

Several SANS studies of ionomers have appeared on both deuterium labeled and unlabeled systems(8,12,18-20). The earlier work(14) showed that an ionic peak, similar to that observed by x-rays, could be discerned in some cases, especially when the sample was "decorated" by the incorporation of D20. It was also tentatively concluded(19) that the radius of gyration, R, of the individual chains is not altered when the acid 1s converted to the salt in the case of poly-styrene-methacrylic acid copolymers. Subsequent SANS experiments were performed on sulfonated polystyrene ionomers with up to 8.5% sul-fonation(12). The results of this study indicated that aggregation of the ionic groups is accompanied by considerable chain expansion, which is consistent with the theory of Forsman(ll). 

The fundamental equation is given below and its various aspects are then discussed. It was applied to data on styrene/methacrylic acid copolymers, Na salts of Eisenberg and Navratil [4,8]. 

Figure 1. Olefinic proton resonances of styrene-methacrylic anhydride copolymers containing both uncycttzed methacrylic anhydride units and absorbed monomer (top), and uncyclized methacrylic anhydride units but little absorbed monomer (bottom). This sample was prepared by reacting a styrene-methacrylic acid copolymer with methacrylic anhydride.

The samples were synthesized by the same techniques as those used for the styrene ionomers (12). The protonated styrene-methacrylic acid copolymers were prepared by thermal initiation. The polymerization took place in sealed glass tubes in the bulk at 80 °C after several freeze-thaw cycles. A conversion of 10% was obtained after 19 hr. The polymer was precipitated in methanol and neutralized in a benzene-methanol solution. A similar procedure was used for the deuterated samples except that the unreacted deuterated styrene monomer was evaporated prior to the precipitation. The mixing of the deuterated and protonated styrene copolymers was performed in a benzene solution by stirring for 1 hr. The benzene used as the solvent contained a minimum amount of methanol necessary to dissolve the ionomer (approximately 5-10% for the samples of high ion content). The samples were freeze-dried, then dried further at 60°-80°C under vacuum, and finally compression-molded at Tg - - 30°C. 

Styrene-Methacrylic Acid Copolymers and Their Salts. Two different types of experiments were performed with these copolymers. A possible clustering of the ionic groups was studied with copolymers containing protonated styrene monomers and deuterated methacrylic acid groups. The radius of gyration measurements were studied from mixtures of all deuterated chains in a protonated matrix. 

In the case of the epoxy-acrylic graft copolymer, the epoxy is not soluble in the monomer mixture, even as low as a 10% solution. However, the epoxy resin being the majority component acts as the continuous phase. The purpose of the graft epoxy-styrene-methacrylic acid copolymer is to lower the barrier at the interface so that a stable oil-in-oil emulsion is first obtained and upon neutralization with a tertiary amine, dimethyl ethanol amine, a stable oil-in-oil emulsion in water is then obtained. 

Epikote resin ester DX-38 is the reaction product of Epikote DX-20 epoxy resin from Shell Chemicals, in which the epoxy rings are reacted with a styrene/methacrylic acid copolymer, further reaction is carried out with linseed oil fatty acids and finally the product is reacted with maleic anhydride to an acid value of 80 mg KOH/g. 

An important example is the preparation of a waterdispersible product by graft polymerization of, for example, styrene-methacrylic acid copolymer onto the aliphatic backbone of a high molecular weight epoxy resin (15). 

The reactivity ratios for styrene-aryl methacrylate copolymerizations [79 — 27] differ significantly from those for the styrene-MMA system, so that copolymers derived from the aryl methacrylate copolymers should have different structures (sequence distributions) than conventional styrene-MMA copolymers of equivalent composition. In the system used to prepare styrene-methacrylic acid copolymers [75], the monomer reactivity ratios are comparable to those of the styrene-MMA system, but the stereochemical structure of the conventional copolymers and of those derived from the methacrylic acid copolymers might be expected to differ. In addition, change of the copolymerization solvent can alter the reactivity ratios for the styrene-methacrylic acid system. Finally, styrene-MMA copolymers derived from styrene-methacrylic anhydride copolymers [22] were expected to have especially interesting structures. The tendency of the anhydride units to become incorporated into the copolymers as cyclic units is very high and there is a great tendency for styrene and cyclic anhydride units in the co-... 

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

Fig. 11. 100 MHz NMR aliphatic proton spectra of styrene-methacrylic acid copolymers in deuteriopyridine solution at 90°. The spectra are of copolymers containing 42 (A), 40 (B) and 27 (C) mole percent methacrylic acid...

Table 3. Correlation of ct-methyl proton resonance patterns observed for styrene-methacrylic acid copolymers with calculated M-centered triad distributions. Data from 100 MHz measurements on copolymers in deuteriopyridine at 70°C...

Table 6. Correlation of proportion of methine resonance occurring at 3 21 b in spectra of styrene-methacrylic acid copolymers with calculated fM M distributions...

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