Fabrication of graded porous structure of hydroxypropyl cellulose hydrogels via temperature-induced phase separation

Alexia Tialiou; Zahraa H Athab; Robert T Woodward; Veronika Biegler; Bernhard K Keppler; Ahmed F Halbus; Michael R Reithofer; Jia Min Chin

doi:10.1016/j.carbpol.2023.120984

Fabrication of graded porous structure of hydroxypropyl cellulose hydrogels via temperature-induced phase separation

Carbohydr Polym. 2023 Sep 1:315:120984. doi: 10.1016/j.carbpol.2023.120984. Epub 2023 May 9.

Authors

Alexia Tialiou¹, Zahraa H Athab², Robert T Woodward³, Veronika Biegler³, Bernhard K Keppler⁴, Ahmed F Halbus⁵, Michael R Reithofer⁶, Jia Min Chin⁷

Affiliations

¹ University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry, Währinger Str. 42, 1090 Vienna, Austria; University of Vienna, Vienna Doctoral School in Chemistry (DoSChem), Währinger Str. 42, 1090 Vienna, Austria.
² University of Babylon, College of Science, Department of Chemistry, Hilla, Iraq; University of Babylon, College of Science, Environmental Research and Studies Center, Hilla, Iraq.
³ University of Vienna, Faculty of Chemistry, Institute of Materials Chemistry and Research, Währinger Str. 42, 1090 Vienna, Austria.
⁴ University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry, Währinger Str. 42, 1090 Vienna, Austria; University of Vienna and Medical University of Vienna, Research Cluster "Translational Cancer Therapy Research", Währinger Str. 42, 1090 Vienna, Austria.
⁵ University of Babylon, College of Science, Department of Chemistry, Hilla, Iraq.
⁶ University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry, Währinger Str. 42, 1090 Vienna, Austria. Electronic address: michael.reithofer@univie.ac.at.
⁷ University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry-Functional Materials, Währinger Str. 42, 1090 Vienna, Austria. Electronic address: jiamin.chin@univie.ac.at.

PMID: 37230621
DOI: 10.1016/j.carbpol.2023.120984

Abstract

A novel hydroxypropyl cellulose (gHPC) hydrogel with graded porosity has been fabricated, in which pore size, shape, and mechanical properties vary across the material. The graded porosity was achieved by cross-linking different parts of the hydrogel at temperatures below and above 42 °C, which was found to be the temperature of turbidity onset (lower critical solution temperature, LCST) for the HPC and divinylsulfone cross-linker mixture. Scanning electron microscopy imaging revealed a decreasing pore size along the cross-section of the HPC hydrogel from the top to the bottom layer. HPC hydrogels demonstrate graded mechanical properties whereby the top layer, Zone 1, cross-linked below LCST, can be compressed by about 50% before fracture, whereas the middle and bottom layers (Zone 2 and 3, respectively) cross-linked at 42 °C, can withstand 80% compression before failure. This work demonstrates a straightforward, yet novel, concept of exploiting a graded stimulus to incorporate a graded functionality into porous materials that can withstand mechanical stress and minor elastic deformations.

Keywords: Graded porous hydrogels; Gradient porous material; HPC; Hydroxypropyl cellulose; LCST; Thermoresponsive hydrogels.