Interconnectivity imaged in three dimensions: Nano-particulate silica-hydrogel structure revealed using electron tomography
Artikel i vetenskaplig tidskrift, 2017

We have used Electron Tomography (ET) to reveal the detailed three-dimensional structure of particulate hydrogels, a material category common in e.g. controlled release, food science, battery and biomedical applications. A full understanding of the transport properties of these gels requires knowledge about the pore structure and in particular the interconnectivity in three dimensions, since the transport takes the path of lowest resistance. The image series for ET were recorded using High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM). We have studied three different particulate silica hydrogels based on primary particles with sizes ranging from 3.6 nm to 22 nm and with pore-size averages from 18 nm to 310 nm. Here, we highlight the nanostructure of the particle network and the interpenetrating pore network in two and three dimensions. The interconnectivity and distribution of width of the porous channels were obtained from the three-dimensional tomography studies while they cannot unambiguously be obtained from the two-dimensional data. Using ET, we compared the interconnectivity and accessible pore volume fraction as a function of pore size, based on direct images on the nanoscale of three different hydrogels. From this comparison, it was clear that the finest of the gels differentiated from the other two. Despite the almost identical flow properties of the two finer gels, they showed large differences concerning the accessible pore volume fraction for probes corresponding to their (two-dimensional) mean pore size. Using 2D pore size data, the finest gel provided an accessible pore volume fraction of over 90%, but for the other two gels the equivalent was only 10-20%. However, all the gels provided an accessible pore volume fraction of 30-40% when taking the third dimension into account.

Silica nanoparticle gel

Porous soft materials

Interconnectivity

Electron tomography

Colloidal silica gel

Accessible volume fraction

Författare

Charlotte Hamngren Blomqvist

SuMo Biomaterials

Chalmers, Fysik, Eva Olsson Group

Tobias Gebäck

Göteborgs universitet

SuMo Biomaterials

Chalmers, Matematiska vetenskaper, Tillämpad matematik och statistik

A. Altskär

Product Design and Perception

Chalmers University of Technology

Anne-Marie Hermansson

Chalmers, Biologi och bioteknik, Livsmedelsvetenskap

SuMo Biomaterials

Stefan Gustafsson

Chalmers, Fysik, Eva Olsson Group

Niklas Lorén

SuMo Biomaterials

Chalmers, Fysik, Eva Olsson Group

Eva Olsson

SuMo Biomaterials

Chalmers, Fysik, Eva Olsson Group

Micron

0968-4328 (ISSN)

Vol. 100 91-105

Ämneskategorier

Fysikalisk kemi

DOI

10.1016/j.micron.2017.04.012