Metal nanoparticle inks

A silver particle ink, comprising:

• particles comprising silver,
• a short-chain capping agent adsorbed on the particles,
• a long-chain capping agent adsorbed on the particles, and
• water,
• wherein the short-chain capping agent is a first anionic polyelectrolyte having a molecular weight (Mw) of at most 10,000,
• the long-chain capping agent is a second anionic polyelectrolyte having a molecular weight (Mw) of at least 25,000, and
• the silver particle ink has a solid loading of metallic silver of at least 50 wt %.

A silver particle ink, comprising:

• particles comprising silver, and
• an ink solvent,
• wherein the silver particle ink has a solid loading of metallic silver of at least 60 wt % and an apparent viscosity of at least about 100 Pa·S at a shear rate of 10−2 1/s,
• the silver particle ink is shear thinning, and
• the silver particle ink has an elastic modulus, G′, and viscous modulus, G″, such that G′>G″.

A method of forming stabilized silver particles, comprising:

• forming a solution comprising a reducing agent, a short-chain capping agent, a long-chain capping agent, and Ag+ ions, to form silver particles;
• and
• growing the silver particles to a mean particle size of 10-50 nm;
• wherein the short-chain capping agent is a first anionic polyelectrolyte having a molecular weight (Mw) of at most 10,000,
• the long-chain capping agent is a second anionic polyelectrolyte having a molecular weight (Mw) of at least 25,000, and
• the reducing agent comprises a hydroxyl group terminated amine containing 2-10 carbon atoms.