11. Li prepared poly(N-isopropyl acrylamide) (PNIPAM) crosslinked microgel particles by an emulsion polymerization of NIPAm with varying amounts of N.N'-methylene bisacryl- amide (Z. Li, E.S. Bates, and T.P. Lodge, ACS Nano, 13, 1232, 2019). Dynamic light scattering revealed that in each case a narrow size distribution was obtained. In order to determine the concentration within each particle, the relative viscosity was measured with a Cannon-Fenske viscometer at 22 C in phosphate buffered saline. The data were com- pared to a theoretical expression for the viscosity of a suspension of spheres, as a function of effective volume fraction Petr (J.F. Brady and M. Vicic, J. Rheol., 39, 545, 1995). Meet = 1+2.5% +5.90l? Use this expression and the flow time data below to calculate the concentration of each particle; does the trend with amount of crosslinker make sense? solvent cg/L 1,5 0 500 0.5% crosslinker cgL I, s 1 522 2 563 3 608 4 676 S 749 6 763 838 977 2.5% crosslinker C, g/L I, s 1 513 3 554 598 649 10 730 5.0% crosslinker cg/L I, s 1 506 3 529 5 553 7 587 10 650 8 11. Li prepared poly(N-isopropyl acrylamide) (PNIPAM) crosslinked microgel particles by an emulsion polymerization of NIPAm with varying amounts of N.N'-methylene bisacryl- amide (Z. Li, E.S. Bates, and T.P. Lodge, ACS Nano, 13, 1232, 2019). Dynamic light scattering revealed that in each case a narrow size distribution was obtained. In order to determine the concentration within each particle, the relative viscosity was measured with a Cannon-Fenske viscometer at 22 C in phosphate buffered saline. The data were com- pared to a theoretical expression for the viscosity of a suspension of spheres, as a function of effective volume fraction Petr (J.F. Brady and M. Vicic, J. Rheol., 39, 545, 1995). Meet = 1+2.5% +5.90l? Use this expression and the flow time data below to calculate the concentration of each particle; does the trend with amount of crosslinker make sense? solvent cg/L 1,5 0 500 0.5% crosslinker cgL I, s 1 522 2 563 3 608 4 676 S 749 6 763 838 977 2.5% crosslinker C, g/L I, s 1 513 3 554 598 649 10 730 5.0% crosslinker cg/L I, s 1 506 3 529 5 553 7 587 10 650 8