Why does a 1H NMR peak of monomer substituent shift after polymerization ? and what makes it shift back when copolymerized with styrene ?

after polymerization, a styrene substituent's NMR peak shift down by few tenths of Hz and broaden when this monomer ( styrene modified on the meta position) is homopolymerized. when this monomer...

20 November 2016 4,481 3 View