Polymeric scaffolds prepared via thermally induced phase separation: Tuning of structure and morphology

Abstract

Scaffolds suitable for tissue engineering applications like dermal reconstruction were prepared by Thermally Induced Phase Separation (TIPS) starting from a ternary solution PLLA/dioxane/water. The experimental protocol consisted of three consecutive steps, a first quench from the homogeneous solution to an appropriate demixing temperature (within the metastable region), a holding stage for a given residence time, and a final quench from the demixing temperature to a low temperature (within the unstable region). A large variety of morphologies, in terms of average pore size and interconnection, were obtained upon modifying the demixing time and temperature, owing to the interplay of nucleation and growth processes during the residence in the metastable state. An interesting combination of micro and macroporosity was observed for long residence times in the metastable state (above 30 min at 35 degrees C). Preliminary degradation tests in a biological mimicking fluid (D-MEM with bovine serum) showed a significant weight loss during the initial stages (ca. 30% in 30 days) related to the degradation of the amorphous part, followed by a negligible weight loss in the next days (few percent from 30 to 60 days).

PLLA/PLA scaffolds prepared via Thermally Induced Phase Separation (TIPS): tuning of properties and biodegradability

“…An homogeneous ternary solution of polymer (pure PLLA, PLLA/PLA 95/5 wt/wt and PLLA/PLA 90/10 wt/wt), dioxane and water was prepared, with a constant dioxane to water weight ratio of 87/13 or 84,5/15,5 based on previous literature studies on the same system 6,7 . The concentration of PLLA was chosen to be 4% wt/wt.…”

Template-based fabrication of nanoporous metals

“…A high degree of pore interconnectedness was observed and was attributed to a spinodal decomposition process in addition to bimodal demixing. 45 This method demonstrates a reliable way to form mesoscale structures with hierarchical pore size distributions and highly interconnected pores that are compatible with the general templating concept.…”

“…45 Figure 4(e) shows a porous PLLA sample with a pore size of 10-15 lm prepared by demixing at 25°C for 5 min, while larger pore sizes of 40-90 lm and porosity as high as 90% shown in Fig. 4(f) were obtained at 30°C for 45 min.…”

“…44 (e, f) PLLA foams prepared by demixing from a PLLA/dioxane/water solution. 45 (g, h) PLLA fibrous scaffolds 46 made from nanofibers in (g) and microfibers in (h).…”

“…Templates act as a support scaffold for metallization procedures in the fabrication of porous metals, enabling a robust processing approach which addresses fundamental difficulties in nanoporous metal assembly and 45 melt mixing, 44 and BCP self-assembly. 38,42,[47][48][49]68 Lines in the figure represent a range of pore sizes or sample sizes.…”