A composition suitable for 3-D printing comprises, in one embodiment, a
photopolymer including one or more
thiol monomer, one or more
alkene monomer, and a
polymerization initiator. In another embodiment, the
thiol monomer is selected from the group consisting of: glycol di(3-mercaptopropionate) [GDMP];
trimethylolpropane tris(3-mercaptopropionate) [TMPMP];
pentaerythritol tetrakis(3-mercaptopropionate) [PETMP] and 3,6-dioxa-1,8-octanedithiol [DODT]. In yet another embodiment, the
alkene monomer comprises: an allyl-functional urethane /
urea monomer synthesized from: an
isocyanate moiety and a hydroxyl or amine functional allyl
moiety. In still another embodiment, the hydroxyl or amine functional allyl
moiety comprises 2-allyloxyethanol,
allyl alcohol, and
allylamine. In still yet another embodiment, the
isocyanate moiety is selected from the group consisting of:
isophorone diisocyanate (IDI),
hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), 1,3-bis(isocyanatomethyl)
cyclohexane, and dicyclohexylmethane 4,4′-Diisocyanate (HMDI).