Tailoring and visualising pore openings in gelatin-based hydrogel foams

Friederike Dehli; Alexander Southan; Wiebke Drenckhan; Cosima Stubenrauch

doi:10.1016/j.jcis.2020.12.064

Tailoring and visualising pore openings in gelatin-based hydrogel foams

J Colloid Interface Sci. 2021 Apr 15:588:326-335. doi: 10.1016/j.jcis.2020.12.064. Epub 2020 Dec 24.

Authors

Friederike Dehli¹, Alexander Southan², Wiebke Drenckhan³, Cosima Stubenrauch⁴

Affiliations

¹ Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
² Institute of Interfacial Process Engineering and Plasma Technology, University of Stuttgart, Nobelstraße 12, 70569 Stuttgart, Germany.
³ Institut Charles Sadron, 23 rue de Loess, Strasbourg 67034, France.
⁴ Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany; Institute of Advanced Studies (USIAS), University of Strasbourg, F-67000, France. Electronic address: cosima.stubenrauch@ipc.uni-stuttgart.de.

PMID: 33422781
DOI: 10.1016/j.jcis.2020.12.064

Abstract

Hypothesis: While tailoring the pore diameters in hydrogel foams has been demonstrated in numerous studies, fine control over the diameters of the pore openings is still a challenge. We hypothesise that this can be achieved by controlling the size of the thin films which separate the bubbles in the liquid foam template. If this is the case, systematic changes of the template's gas fraction ϕ (the higher ϕ, the larger are the thin films) will lead to corresponding changes of the pore opening diameter.

Experiments: Since the size of the thin films depends on both bubble size 〈D_b〉 and gas fraction ϕ, we need to decouple both parameters to control the film size. Thus, we generated foams with constant bubble sizes via microfluidics and adjusted the gas fractions via two different techniques. The foams were solidified using UV light. Subsequently, they were analysed with confocal fluorescence microscopy.

Findings: We were able to change the pore opening diameter 〈d_p〉 at a constant pore diameter 〈D_p〉 by adjusting the gas fraction of the foam template. The obtained 〈d_p〉/〈D_p〉 ratios are between those obtained theoretically for disordered foams and FCC ordered foams, respectively.

Keywords: Biopolymer scaffolds; Foam templating; Gelatin methacryloyl; Microfluidics; Pore opening.