Particle leaching
Highly porous scaffolds can be fabricated by particle leaching using sodium chloride (NaCl) particles as a porogen (51). Sun et al.
(51) demonstrated that the porosity of scaffolds is almost independent of the porogen size, but instead is dependent on the amount of porogen.
The maximum porosity of scaffolds can reach about 85%, when the weight ratio of porogen to polymers is 9:1.
The fabrication process began with dissolving 2 g PHBHHx powder in 20 mL chloroform in a 50-mL conical flask and then 0.04 g NaCl crystals was suspended in the PHBHHxchloroform solution and mixed by shaking.
Tube construction was carried out using a 2.5-mm diameter stainless steel mandrill, which was dipped into the homogenized PHBHHx/NaCl solution for 1 s, followed by solvent evaporation in a flow hood for 2 min.
This process was repeated five times, after which the mandrill was fixed vertically for 60 min to allow the solvent to fully evaporate and the polymer to become rigid.
The polymer tube was carefully removed by hand and immersed in deionized H2O overnight to introduce porosity through NaCl crystal dissolution.