We report measurements of the bulk modulus of individual poly(N-isopropylacrylamide) microgels along their swelling transition. The modulus is determined by measuring the volume deformation of the microgel as a function of osmotic pressure using dextran solutions. We find that the modulus softens through the transition, displaying a nonmonotonous behavior with temperature. This feature is correctly reproduced by the theory of Flory for polymer gels, once the concentration dependence of the solvency parameter is properly incorporated.
Sierra, M., B.; Laporte, Y.; South, A. B.; Lyon, L. A.; Fernandez-Nieves, A., Bulk modulus of poly(N-isopropylacrylamide) microgels through the swelling transition, Physical Review E 2011, 84 (1), 011406. DOI:10.1103/PhysRevE.84.011406
American Physical Society