a polymer containing 50 by weight sodium styrene sulfonate and 50 of vinyl naphthalene was prepared in benzene solution aibn as catalyst after isolation and purification by dialysis against pure water it had a molecular weight m w of 200 000 100 mg of this polymer was dissolved in 100 ml distilled water and after purging with oxygen free nitrogen was irradiated with a dose of 0 40 megarad of cobalt 60 u03b3 rays a f m analysis of the resulting particles showed spherical particles with an average diameter of 7 5 nanometers the a f m picture of the particles is presented as fig4 hereof a 1 solution of these particles in water showed very little increase over that of water itself internal cross linking can be carried out by other means besides y radiation in some cases irradiation of the aqueous dispersion with high intensity u v laser light will cause internal cross linking a simpler procedure is to prepare a copolymer with a small number of double bonds which can be connected by vinyl polymerization in this example a copolymer of 50 styrene sulfonate and 48 vinyl naphthalene and 2 divinyl benzene was prepared as in example 3 100 mg of this polymer was dissolved in 100 ml.