Influence of the Processes Parameters on the Properties of The ...
Influence of the Processes Parameters on the Properties of The ...
Influence of the Processes Parameters on the Properties of The ...
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Chapter 2.<br />
<str<strong>on</strong>g>Processes</str<strong>on</strong>g> to Manufacture Foams and to Functi<strong>on</strong>alize <str<strong>on</strong>g>the</str<strong>on</strong>g> Surface<br />
quenching depth, ageing time, polymer c<strong>on</strong>centrati<strong>on</strong>, molecular weight, solvent/n<strong>on</strong> solvent compositi<strong>on</strong>,<br />
and additives.<br />
<strong>The</strong> schematic procedure for <str<strong>on</strong>g>the</str<strong>on</strong>g>rmally induced phase separati<strong>on</strong> is given in Figure 2.8.<br />
Polylactide soluti<strong>on</strong> with a mixture <str<strong>on</strong>g>of</str<strong>on</strong>g> good and bad solvent is prepared [Figure a]. <strong>The</strong> sample is reheated to<br />
15°C above <str<strong>on</strong>g>the</str<strong>on</strong>g> measured cloud point temperature, and <str<strong>on</strong>g>the</str<strong>on</strong>g>n placed in a water bath preheated to <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
quenching temperature. It is kept for 2, 10, 30, 60 or 120 min, at <str<strong>on</strong>g>the</str<strong>on</strong>g> quenching temperature. <strong>The</strong> annealed<br />
sample is directly immersed in liquid nitrogen to be fast-frozen for 1 h, and <str<strong>on</strong>g>the</str<strong>on</strong>g>n a small hole is cut in <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
vial cap to release <str<strong>on</strong>g>the</str<strong>on</strong>g> solvent [Figure b].<br />
Freeze-drying is performed in a freeze-dryer at −77°C and 7 mTorr for 3 days in order to remove<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g> solvent and obtain <str<strong>on</strong>g>the</str<strong>on</strong>g> macroporous scaffolds [Figure c]. <strong>The</strong> dry scaffolds are cut into cubes with a<br />
surgical blade. Prior to cell seeding, 3D scaffolds are pre-wetted with 70% ethanol for 3 h to sterilise <str<strong>on</strong>g>the</str<strong>on</strong>g>m<br />
and enhance <str<strong>on</strong>g>the</str<strong>on</strong>g>ir water uptake. <strong>The</strong> ethanol is removed by soaking with agitati<strong>on</strong> for 1 h in six changes <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
PBS, and <str<strong>on</strong>g>the</str<strong>on</strong>g>n <str<strong>on</strong>g>the</str<strong>on</strong>g> scaffolds are left overnight in <str<strong>on</strong>g>the</str<strong>on</strong>g> culture media.<br />
Figure 2.8: Schematic preparati<strong>on</strong> processing <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>rmally induced phase separati<strong>on</strong> method.<br />
[Kim and Doo, 2007a]<br />
2.9 Centrifugati<strong>on</strong> Method<br />
Recently, a centrifugati<strong>on</strong> method has been introduced as an effective method to fabricate<br />
scaffolds that have various shapes with a uniform surface and inside pore structures. <strong>The</strong> scaffolds can be<br />
fabricated in various shapes from many different natural and syn<str<strong>on</strong>g>the</str<strong>on</strong>g>tic polymers by <str<strong>on</strong>g>the</str<strong>on</strong>g> centrifugati<strong>on</strong><br />
method (cf. Figure 2.9).<br />
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