A polymer engineer is choosing an ultrafiltration membrane to remove a soluble low molecular weight catalyst from a polymer product. The polymer, in this case is polystyrene, been synthesized in solution. If a membrane has a pore size of 20 nm, estimate what is the smallest polymer molecular weight that could be retained (ie not pass through the membrane.) The polystyrene and catalyst are dissolved in cyclohexane at 35C (theta conditions). Note, the bond length of a polystyrene repeat unit is 3A, while the repeat unit molecular weight and characteristic ratio for this polymer are 104 g/mol and 10.8, respectively.