The living/controlled radical copolymerization of 1
2:3
4-di-O-isopropylidene-6-O-(2'-formyl-4'-vinylphenyl)-D-galactopyranose (IVDG) and 5
6-benzo-2-methylene-1
3-dioxepane (BMDO)
was successfully achieved using dicumyl peroxide (DCP) as the initiator and 1-phenylethyl phenyldithioacetate (PEPD) as the reversible addition-fragmentation chain transfer (RAFT) agent at 130℃ in anisole.The number-average molecular weight of the obtained copolymers increased in direct proportion to the monomer conversion
and the molecular weight distribution was narrow (polydispersity index 1.4).Various copolymers of BMDO with IVDG were synthesized by changing the molar ratio of the two monomers in the initial feed using PEPD as chain transfer reagent under RAFT reaction conditions.There was an increase in the molecular weight from 5.2103 to 1.8104 on increasing the molar ratio of IVDG:BMDO from 20:80 to 70:30.In general
the molecular weight of the polymers increased with increase in the amount of IVDG in the copolymers.Moreover
the copolymer composition was determined by taking the ratio of peak areas of aldehyde protons of IVDG to that of of BMDO.It is observed that the mole fraction of BMDO was less in copolymers as compared to that in the initial feed.The result was mostly because the BMDO radical is neighbor to two electron-rich oxygen atoms so as to have lower reactivity as compared to IVDG radical.The copolymer compositions and structural characterization were obtained from 1H-NMR spectroscopy.Degradation behavior of these copolymers was also investigated.Removal of protective isopropylidene groups from the sugar residue in poly(BMDO-co-IVDG) was carried out quantitatively using 88% formic acid at room temperature
yielding a novel amphiphilic copolymer containing both galactopyranose and aldehyde functionalities.These amphiphilic glycopolymers self-assembled into well-defined degradable and biocompatible aldehyde-functionalized polymeric nanospheres in aqueous solutions without recourse to any surfactant.The nanospheres obtained from the resultant glycopolymer are possible to be used as nanoparticle targeted drug-delivery system.