This work has investigated two routes of synthesizing polymers containing L-histidine using maleimide chemistry; grafting of histidine onto an ethylenealt- maleic anhydride copolymer and AIBN (azobisisobutyronitrile) initiated radical polymerisation of the monomer maleoyl-L-histidine. The grafting technique and monomer synthesis are utilising the maleimide formation between the primary amine of histidine and maleic anhydride. The reactions are conveniently carried out in one step with good yields. The copolymers containing L-histidine were prepared by reacting L-histidine or Lhistidine methyl ester with poly(ethylene-alt maleic anhydride) in DMSO at 50 °C for 8-16 h with 80% yields independent of the degree of substitution. The monomer maleoyl-L-histidine was synthesised by reacting histidine and maleic anhydride in acetic acid and the monomer was subsequently polymerised by AIBN radical initiation in DMSO at 80 °C for 48 h to yield poly(N-histidyl maleimide). The resulting polymer had a different optical rotation ([α]D 20=-11) than the monomer ([α]D 20=+25), which is ascribed to the threo-diisotactic and/or threodisyndiotactic stereoregularity of the polymer.
- Maleic anhydride
- Radical polymerization
- Post-polymerisation modification