Nanoporous polymer hydrogels offer a desirable combination of mechanical,
optical, and transport characteristics that have placed them at the core of a variety of
biomedical technologies including engineered tissue scaffolds, substrates for controlled
release of pharmaceutical compounds, and sieving matrices for electrophoretic
separation of DNA and proteins. Ultimately, we would like to obtain a detailed picture
of the nanoscale pore morphology and understand how it can be manipulated so that we
can rationally identify gel formulations best suited for a specific application. But this
goal has proven elusive because the most fundamental descriptors of the pore network
architecture (e.g., the average pore size and its polydispersity) are particularly difficult to
measure in polymer hydrogels.
Here we introduce an approach that enables both the mean pore size and the pore
size distribution to be quantitatively determined without prior knowledge of any physical
material parameters A novel technique to prepare TEM samples was developed so that
the nanoscale hydrogel pore size, pore shape and distribution are clearly visualized and quantitatively studied for the first time. The pore sizes of the hydrogel are also estimated
with rheology. A new fixture is used in the rheometer and the whole polymerization
process can be directly studied using an in-situ rheology experiment. A series of
thermoporometry experiments are also conducted, and suitable methods and equations to
study hydrogel pore size and distribution are chosen. The pore size derived from TEM,
rheology, DSC is compared and their values are self-consistent. These techniques help
us understand how the nanoporous morphology of crosslinked polyacrylamide hydrogels
is influenced by their chemical composition and polymerization conditions.
It is interesting to find hydrogels with similar pore size but different distribution.
For two hydrogels with similar pore size, the broader the distribution, the faster the
release rate and the higher the accumulated release percentage. So we can control the
release of trapped molecules by simply varying the hydrogel pore size distribution. This
discovery would have a very promising potential in the application of pharmaceuticals.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2687 |
| Date | 15 May 2009 |
| Creators | Wang, Jian |
| Contributors | Ugaz,Victor M |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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