4. All the final compounds included in the scaffolds are suited for
biomedical applications. Intermediary reagents and
by-products are removed during the procedure of purification
for each step of the synthesis.
5. Ungrafted methacrylates from methacrylate anhydride or
methacrylic acid are visible in the NMR spectra at different
chemical shifts than the methacrylates grafted to the polymer,
which therefore allows the reaction process to be followed, and
the elimination of unreacted methacrylates by precipitation.
6. The methacrylated polymers can be defined as a photoactive
resin, macromer, macromonomer, or prepolymer.
In the absence of photoinitiator, the acrylate groups are
hardly susceptible to photo-curing; however it is recommended
to protect the resin from light during storage and building
process to prevent premature crosslinking. It is recommended
to store resin batches in a freezer, especially for PDLLA resins,
which are highly sensible to degradation by hydrolysis.
7. Drying procedures must be performed under vacuum at room
temperature. Rising the temperature may initiate unexpected
thermal crosslinking.
8. Optimal viscosity has been found around 10 Pa·s; however
higher or lower viscosity can also be used. Viscosity can be
adjusted by dilution in a solvent with high boiling temperature
to prevent evaporation and modification of the resin concentration. Use of an apparatus equipped with heater can also be
suggested to reduce the viscosity.
9. The end-functionalization reaction might lead to a yellow solution, which is due to the oxidation of the trimethylamine added
in the reaction but does not impair the efficiency of the
reaction.
10. Radical photopolymerization of methacrylates is known to be
efficient and fast, but in case of low crosslinking efficiency or
weak mechanical properties of the building object, curing can
be enhanced using a reactive solvent (e.g., NVP) or crosslinker
(e.g., di- or tri-acrylate).
11. Dyes such as Orange Orasol are suggested in order to avoid the
over-curing of the resin into a preceding layer.
12. Radical photopolymerization is inhibited in presence of oxygen, and the reaction should be ideally maintained continuously under flow of inert gas like argon or nitrogen. This
caution can be taken conveniently during the initial curing
tests process using a UV cabinet but remains hard to set up
during the building by SL. That is why the bottom-up
approach significantly limits the contact with the environment
and the photopolymerization is only little impaired by oxygen.
28
Sebastien B. G. Blanquer and Dirk W. Grijpma
biomedical applications. Intermediary reagents and
by-products are removed during the procedure of purification
for each step of the synthesis.
5. Ungrafted methacrylates from methacrylate anhydride or
methacrylic acid are visible in the NMR spectra at different
chemical shifts than the methacrylates grafted to the polymer,
which therefore allows the reaction process to be followed, and
the elimination of unreacted methacrylates by precipitation.
6. The methacrylated polymers can be defined as a photoactive
resin, macromer, macromonomer, or prepolymer.
In the absence of photoinitiator, the acrylate groups are
hardly susceptible to photo-curing; however it is recommended
to protect the resin from light during storage and building
process to prevent premature crosslinking. It is recommended
to store resin batches in a freezer, especially for PDLLA resins,
which are highly sensible to degradation by hydrolysis.
7. Drying procedures must be performed under vacuum at room
temperature. Rising the temperature may initiate unexpected
thermal crosslinking.
8. Optimal viscosity has been found around 10 Pa·s; however
higher or lower viscosity can also be used. Viscosity can be
adjusted by dilution in a solvent with high boiling temperature
to prevent evaporation and modification of the resin concentration. Use of an apparatus equipped with heater can also be
suggested to reduce the viscosity.
9. The end-functionalization reaction might lead to a yellow solution, which is due to the oxidation of the trimethylamine added
in the reaction but does not impair the efficiency of the
reaction.
10. Radical photopolymerization of methacrylates is known to be
efficient and fast, but in case of low crosslinking efficiency or
weak mechanical properties of the building object, curing can
be enhanced using a reactive solvent (e.g., NVP) or crosslinker
(e.g., di- or tri-acrylate).
11. Dyes such as Orange Orasol are suggested in order to avoid the
over-curing of the resin into a preceding layer.
12. Radical photopolymerization is inhibited in presence of oxygen, and the reaction should be ideally maintained continuously under flow of inert gas like argon or nitrogen. This
caution can be taken conveniently during the initial curing
tests process using a UV cabinet but remains hard to set up
during the building by SL. That is why the bottom-up
approach significantly limits the contact with the environment
and the photopolymerization is only little impaired by oxygen.
28
Sebastien B. G. Blanquer and Dirk W. Grijpma