MICROSTRUCTURE OF STYRENE-METHACRYLIC ACID AND STYRENE-ACRYLIC ACID COPOLYMERS .5. UV ABSORPTION STUDY OF STYRENE-METHACRYLIC ACID AND STYRENE-ACRYLIC ACID COPOLYMERS

UV absorption spectra of styrene-methacrylic acid and styrene-acrylic acid copolymers prepared in benzene solution and in emulsion were inve stigated, They were compared to UV spectra of derived copolymers prepa red by methylation of the carboxyl groups of the parent copolymers. In the spectra of the methylated copolymers only a hypochromic effect on all peaks was observed, whereas in the spectra of the parent acid cop olymers hypochromic as well as hyperchromic effects were found. They d epend on the kind of acid, its content in the copolymer and on the typ e of the copolymer. These differences may be explained on the basis of hydrogen bonds formed between the pi-electrons of phenyl rings and ca rboxyl groups. It seems that the most sensitive peak to these hydrogen bonds is that at 259 nm, while the peak at 269 nm is sensitive to ele ctronic interactions between adjacent monomeric units.