3D Micromorphology Producing within Poly(lactic acid) Skeleton Using Room-Temperature Ionic Liquids: From Particulate, Fibrous or Porous Scaffolds to Beads

We describe herein a three-dimensionally diverse micropatterning of poly(lactic acid), as a biopolymer, using 1-butyl-3-methylimidazolium-based room-temperature ionic liquids (bmim-based RTILs), [bmim]X (X = $SbF_6$, $PF_6$, $NTf_2$, Cl). Utilizing the hydrophobic bmim-based RTILs, [bmim]X (X = $SbF_6$, $PF_6$, $NTf_2$) and a phase separation technique, we were able to produce white and opaque membranes with a three-dimensional structure closely packed with particles ($10-50{\mu}m$ in diameter). The particlulate structure, made by the assistance of [bmim]$NTf_2$ and DCM, interestingly transformed to a fibrous structure by using a cosolvent, e.g., DCM/$CF_3CH_2OH$. When we used an increased amount of [bmim]$NTf_2$, the particles were effectively detached and macrosized ($100-500{\mu}m$ in diameter) and the oval-shaped beads were obtained in a powder form. By varying the counter-anion type of the imidazolium-based RTIL, for example from $NTf_2^-$ to $Cl^-$, the particulate 3D-morphology was once more transformed to a porous structure. These reserch results could be potentially useful, as a method to fabricate particulate scaffolds, fibrous or porous scaffolds, and beads as a biopolymer device in diverse fields including drug delivery, tissue regeneration, and biomedical engineering.