A sample of polystyrene (monomer molar mass

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Soft condensed matter · Soft condensed matter

Soft Matter at the Thermal Scale, Ch Polymer solutions and blends

Problem

M_0 = 104\,\mathrm{g\,mol^{-1}}

, bulk polymer density

\rho = 1050\,\mathrm{kg\,m^{-3}}

) is dissolved in toluene at

T = 298\,\mathrm{K}

. Take each lattice site to be one styrene monomer, of volume

v_0 = M_0/(\rho N_{\rm Av})

, about the size of one toluene molecule. Membrane osmometry gives

\Pi = 66.5\,\mathrm{Pa}

c = 2.0\,\mathrm{g\,L^{-1}}

, and

\Pi = 226.6\,\mathrm{Pa}

c = 6.0\,\mathrm{g\,L^{-1}}

. ((a)) Find the molar mass

M

of the polystyrene from the intercept of

\Pi/c

plotted against

c

. ((b)) Find the Flory-Huggins parameter

\chi

from the slope of the same plot.