0M. 1M. 2M. T. Tominaga 1,2 , V.R. Tirumala 1 , P.D. Butler 1 , E.K. Lin 1 , H. Furukawa 2 , J.P. Gong 2 , Y. Osada 2 , and W.-L. Wu 1. Why are double-network hydrogels so tough?. 1 NIST, 2 Hokkaido University. DMR-0454672.
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T. Tominaga1,2, V.R. Tirumala1, P.D. Butler1, E.K. Lin1, H. Furukawa2, J.P. Gong2, Y. Osada2, and W.-L. Wu1Why are double-network hydrogels so tough?
1NIST, 2Hokkaido University
Double network hydrogels (DN-gels) are prepared by polymerizing a high molecular weight linear polymer within a swollen polyelectrolyte network. The linear polymer is highly viscous and readily deformable (like putty) whereas the polyelectrolyte network is rigid but fragile (like jelly). Neither component is tough, yet DN-gels have fracture toughness comparable with joint cartilage. At the same time > 90% by volume is water.
Using three NCNR small angle scattering instruments including the CHRNS 30-m SANS and USANS, combined with selective deuteration to control the scattering contrast, we have studied the structures of DN-gels and those of their components, PAMPS1 and PAAm2. The results suggest that the heterogeneity decreases and then increases with addition of PAAm.
Structural changes in the PAMPS gel with addition of PAAm to form the toughest DN-gel can be conceptualized as shown below.
1 PAMPS: poly(2-acrylamide,2-methyl,1-propane sulfonic acid) 2 PAAm: polyacrylamide
Contrast-normalized scattering intensities for DN-gels with different concentrations of PAAm, measured over four orders of magnitude in q (inverse length).
T. Tominaga, V.R. Tirumala, P.D. Butler, E.K. Lin, H. Furukawa, J.P. Gong, Y. Osada, and W.-L. Wu, paper in preparation.