Synthesis of ATRP macroinitiator based on synthetic cis-1,4-polyisoprene and its application for graft polymerization of MMA

Modification of synthetic cis-1,4-polyisoprene (PI) into bromoalkyl-functionalized polyisoprene (PIBr), an ATRP macroinitiator, was investigated by two-step chemical reaction. The PI was partially epoxidized into epoxidized polyisoprene (EPI) using m-chloroperbenzoic acid, then the EPI was transformed into PIBr by reaction with 2-bromo-2-methylpropionic acid. The results from ¹H NMR revealed that the addition product occurs in competition with epoxide ring rearrangement. The amount of bromoalkyl functionalized units was determined from ¹H NMR spectra. The graft polymerization of MMA using ATRP technique from macroinitiator units in PIBr was investigated using three different ligands, i.e. N-(n-octyl)-2- pyridylmethanimine (NOPMI), N-(n-octadecyl)-2-pyridylmethanimine (NODPMI) and 1,1,4,7,7-pentamethyldiethylenetriamine (PMDETA), resulting in formation of graft copolymer of PI and PMMA. The PMMA grafts were successfully separated from the PI backbone using acidolysis for studying their number-average molecular weights (M_n,SEC) and polydispersity indexes (PDI). All of the ligands used give a increase of M̄_n with MMA conversion. Comparing between 3 ligands, Cu(I)Br complexed with NOPMI shows first-order kinetic plot.