The nanoporous morphology of photopolymerized crosslinked polyacrylamide hydrogels

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Title: The nanoporous morphology of photopolymerized crosslinked polyacrylamide hydrogels
Author: Wang, Jian
Abstract: 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 .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2687
Date: 2009-05-15

Citation

The nanoporous morphology of photopolymerized crosslinked polyacrylamide hydrogels. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2687 .

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