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

Abstract

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 (Mn,SEC) and polydispersity indexes (PDI). All of the ligands used give a increase of M̄n with MMA conversion. Comparing between 3 ligands, Cu(I)Br complexed with NOPMI shows first-order kinetic plot.