5. Once the resin is prepared, the machine is calibrated through a
working curve in order to precisely control the depth of cure in
the resin layers. This working curve is established by measuring
the photocrosslinked layer thickness for several exposure time
at a certain intensity of irradiation. The correlation between the
exposure time and the thickness layer expected during the
building by the SL can be made using an adapted equation
from the Beer-Lambert equation. This procedure has been
excellently described and explained in the review from Melchels
et al. [2]. On average for the PTMC and PDLLA resins, the
required curing time is around 50 s with a light intensity of
18 mW/cm
2 for a sequentially layer thickness of 25 μm.
6. 3D fabrication occurs in a resin bath comprising a non-UVabsorbing plate (e.g., quartz, PDMS, etc.). For a support
platform of 100 cm
2 , the resin bath should have a surface of
at least 120 cm
2 for a global volume of resin around 25 mL (see
Note 13). Such volume is required to make twice building of
20 cubic scaffolds (1 cm
3 ).
7. After building, collect scaffolds from the platform and remove
non-reacted resin by several extraction cycles (see Note 14).
Extract non-reacted resin in 100% propylene carbonate,
refreshing solvent three times a day. Exchange propylene carbonate by acetone in order to facilitate the drying step with the
following acetone/propylene carbonate ratios: 20:80, 50:50;
75:25, and finally 100% acetone. Vacuum-dry scaffolds for
several hours (see Note 15).
8. Structural and textural scaffold characterizations are performed
by scanning electron microscopy (SEM) and micro-computed
tomography (μCT) (see Note 16). Pore features in terms of
interconnectivity, porosity, pore distribution, and strut thickness distribution can be assessed by these visualization analyses
[3, 19].
4 Notes
1. The monomers are stored at À20
C, and consequently before
the polymerization, it is advised to equilibrate the monomers
batches at room temperature before opening the sealed
container.
2. Ring opening polymerization must be done in rigorous anhydrous environment. The presence of water initiates the ring
opening polymerization.
3. Solubilization of PTMC or PDLLA oligomers is facilitated by
stirring, but even then, it may require some time for high
amounts of material.
TPMS Scaffolds by Stereolithography
27
working curve in order to precisely control the depth of cure in
the resin layers. This working curve is established by measuring
the photocrosslinked layer thickness for several exposure time
at a certain intensity of irradiation. The correlation between the
exposure time and the thickness layer expected during the
building by the SL can be made using an adapted equation
from the Beer-Lambert equation. This procedure has been
excellently described and explained in the review from Melchels
et al. [2]. On average for the PTMC and PDLLA resins, the
required curing time is around 50 s with a light intensity of
18 mW/cm
2 for a sequentially layer thickness of 25 μm.
6. 3D fabrication occurs in a resin bath comprising a non-UVabsorbing plate (e.g., quartz, PDMS, etc.). For a support
platform of 100 cm
2 , the resin bath should have a surface of
at least 120 cm
2 for a global volume of resin around 25 mL (see
Note 13). Such volume is required to make twice building of
20 cubic scaffolds (1 cm
3 ).
7. After building, collect scaffolds from the platform and remove
non-reacted resin by several extraction cycles (see Note 14).
Extract non-reacted resin in 100% propylene carbonate,
refreshing solvent three times a day. Exchange propylene carbonate by acetone in order to facilitate the drying step with the
following acetone/propylene carbonate ratios: 20:80, 50:50;
75:25, and finally 100% acetone. Vacuum-dry scaffolds for
several hours (see Note 15).
8. Structural and textural scaffold characterizations are performed
by scanning electron microscopy (SEM) and micro-computed
tomography (μCT) (see Note 16). Pore features in terms of
interconnectivity, porosity, pore distribution, and strut thickness distribution can be assessed by these visualization analyses
[3, 19].
4 Notes
1. The monomers are stored at À20
C, and consequently before
the polymerization, it is advised to equilibrate the monomers
batches at room temperature before opening the sealed
container.
2. Ring opening polymerization must be done in rigorous anhydrous environment. The presence of water initiates the ring
opening polymerization.
3. Solubilization of PTMC or PDLLA oligomers is facilitated by
stirring, but even then, it may require some time for high
amounts of material.
TPMS Scaffolds by Stereolithography
27