posted on 2007-04-24, 00:00authored bySarvesh K. Agrawal, Naomi Sanabria-DeLong, Pete R. Jemian, Gregory N. Tew, Surita R. Bhatia
We observe large-scale structures in hydrogels of poly(l-lactide)−poly(ethylene oxide)−poly(l-lactide) (PLLA−PEO−PLLA) ranging in size from a few hundred nanometers to several micrometers. These structures are apparent
through both ultra-small angle scattering (USAS) techniques and confocal microscopy. The hydrogels showed power
law scattering in the USAS regime, which is indicative of scattering from fractal structures. The fractal dimension
of the scattering from hydrogels revealed that the gels have large size aggregates with a mass fractal structure over
the nanometer-to-micrometer length scales. The aggregates also seem to become more “dense” with an increase in
the molecular weight of crystalline PLLA domains. Visualization through confocal microscopy confirms that the gels
have a microstructure of interspersed micrometer-sized polymer inhomogeneities with water channels running between
them. The presence of micrometer-sized water channels in the hydrogels has very important implications for biomedical
applications.