The starting materials used for reaction were sebacic acid (2 N purity) and
glycerol (2 N purity). The pre-polymers were prepared by simultaneous addition of
the certain amounts of sebacic acid and glycerol monomers into a flask with sebacic
acid and glycerol at ratio of 1:1 at 150 C under nitrogen for 4 h. 5-FU was mashed
and then mixed with pre-polymers with adding ethanol as solvent. The mixture was
heated to 70 C and stirred until total dissolution. Then, polymerization reaction was
processed in vacuum under 150 C for 30 h. Because the boiling point of ethanol is
78 C under 1 atm, all ethanol will be volatilized without residual under the present
polymerization conditions. The raw material compositions of different samples are
given in Table 1. 5-FU-PGS wafers were prepared in round size with 10 mm diameter
and 1–1.5 mm thickness.
2.