| Abstract: |
Double-network hydrogels (DN-gels) prepared from the combination of a moderately crosslinked anionic polyelectrolyte and an uncrosslinked linear polymer solution exhibit mechanical properties such as fracture toughness that are intriguingly superior to that of their individual constituents. The scheme of double network preparation, however, is not equally successful for all polyelectrolyte/neutral polymer pairs. A successful example is the combination of poly (2-acrylamido, 2-methyl, 1 propane sulfonic acid) (PAMPS) crosslinked network and linear polyacrylamide (PAAm), which results in DN-gels with fracture toughness approaching that of articular cartilage ( 20 MPa).As a first step to elucidate the molecular origin responsible for this superior property, small-angle neutron scattering was used to determine the thermodynamic interaction parameters for PAMPS and PAAm in water. Measurements on PAMPS/PAAm DN-gels and their solution blend counterparts indicate that a favorable interaction exists between these two polymers. This favorable PAMPS/PAAm interaction given by the condition, ?PE-NP <
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