Microstructure of styrene‐methacrylic acid and styrene‐acrylic acid copolymers, 3. UV absorption study of methylated styrene‐methacrylic acid and styrene‐acrylic acid copolymers

Abstract The microstructure of styrene‐methacrylic acid and styrene‐acrylic acid copolymers prepared in emulsion was studied by UV absorption measurements of their methylated derivatives. For comparative purpose random and graft‐block copolymers were also studied. Hypochromic effects at 259, 262, 264,5 and 269 nm are observed for both random and emulsion copolymers. The dependence of hypochromism at 269 nm on the content of methylated acid units suggests a similar microstructure of random and emulsion copolymers containing up to about 30 mol‐% of acid and differences in the microstructure of emulsion and random copolymers containing greater amounts of acid, especially in case of styrene‐acrylic acid copolymers. Moreover, it is found that UV absorption measurements may be used as a method of estimating the sequence length of styrene units in the copolymers.