Controlled radical polymerization of N-Vinylphthalimide using carboxyl-terminated trithiocarbonate as RAFT agent and preparation of microfibers via electrospinning technique

Reversible addition-fragmentation chain transfer (RAFT) polymerization of N-vinylphthalimide in N,N-dimethylformamide (DMF) solution was carried out using 2-carboxypropan-2-yl dodecyl trithiocarbonate as a reversible chain transfer agent in the presence of 2,2-azobisisobutyronitrile. The molecular weights of the polymers increased linearly with the monomer conversion and the molecular weight distributions were relatively narrow (PDI < 1.2). It is confirmed by chain extension reaction that the polymer prepared via RAFT polymerization can be used as a macro-RAFT agent. The structure of both polymers was characterized and confirmed by size-exclusion chromatography and 1H-NMR techniques. Ultrafine microfibers were prepared by electrospinning of poly(N-vinylphthalimide) in DMF solution. The effects of electrospinning process parameters such as voltage, tip-to-collector distance, and solution concentration on the morphology and the average size of the electrospun fibers were studied. To evaluate the fiber diameters, scanning electron microscope micrographs of the microfibers were performed.