STABILITY OF THE CHAIN STRUCTURE OF A STYRENE-ISOPRENE DIBLOCK COPOLYMER DURING THE HYDROGENATION BY DIIMIDE

Olefinic double bonds of a model styrene-isoprene diblock copolymer were hydrogenated using diimide (generated by a thermal decomposition of p-toluenesulfonyl hydrazide). The presence of byproducts and/or main-chain structural alterations (e.g., degradation or crosslinking), as a possible side effect of this polymer analogous reaction, was checked by NMR spectroscopy, elemental analysis, static and dynamic light scattering, and GPC. A twofold concentration of Irganox 1010 antioxidant in the reaction mixture (as compared to the original reported procedure) seems to inhibit the formation of byproducts as well as to prevent any alterations on the macromolecular level. No reactions of isoprene monomer units (other than the addition of hydrogen atoms) and no changes in molar-mass distribution of the substrate were detected by the methods used.