Method of making silver-containing dispersions

A method comprising, in sequence:

• A) mixing:
• (a) one or more polymers selected from one or more of cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate trimellitate, hydroxypropylmethyl cellulose phthalate, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, and carboxymethyl cellulose;
• (c) one or more organic solvents, each of which has a boiling point at atmospheric pressure of greater than or equal to 90° C. and up to but less than 500° C., wherein the total Hansen parameter (δTPolymer) of each of the one or more polymers is less than or equal to the total Hansen parameter (δTSolvent) of each of the one or more organic solvents;
• (d) a nitrogenous base having a pKa in acetonitrile of at least 15 and up to and including 25 at 25° C.;
• and
• (e) ascorbic acid,
• to form a premix solution;
• B) maintaining the premix solution at room temperature or heating the premix solution to a temperature of at least 40° C.;
• C) while keeping the premix solution at room temperature or at the temperature of at least 40° C., adding a solution of either (b) reducible silver ions or (b′) reducible copper ions, in one or more (c) organic solvents to provide an amount of the (b) reducible silver ions or (b′) reducible copper ions, respectively, in the premix solution that is equimolar or less in relation to the (d) nitrogenous base, and a weight ratio of the (b) reducible silver ions or (b′) reducible copper ions to the (a) one or more polymers of at least 5:1 and up to and including 50:1,
• to form either a silver nanoparticle composite or a copper nanoparticle composite, respectively;
• wherein the (e) ascorbic acid is provided in a molar amount of at least 0.01:1 relative to either the (b) reducible silver ions or (b′) reducible copper ions, respectively, and
• the (d) nitrogenous base is provided in a molar amount of at least 1:1 and up to and including 3:1 relative to either the (b) reducible silver ions or (b′) reducible copper ions, respectively,
• D) after cooling, isolating the silver nanoparticle composite or the copper nanoparticle composite;
• and
• E) re-dispersing either the silver nanoparticle composite or the copper nanoparticle composite, as described above in C), to provide either a non-aqueous silver-containing dispersion or a non-aqueous copper-containing dispersion, comprising the silver nanoparticle composite or the copper nanoparticle composite, respectively.