1. An anti-reflective coating composition comprising: a liquid medium comprising a majority amount of organic solvent; polymer particles dispersed in the liquid medium, the polymer particles comprising: at least one tetraalkoxy silane residue including a silicon atom bonded to four oxygen atoms; and at least one second alkoxy silane residue including a silicon atom bonded to at least one carbon atom, the at least one second alkoxy silane residue selected from the group consisting of trialkoxy silanes, dialkoxy silanes, monoalkoxy silanes, and combinations thereof, wherein the polymer particles comprise 35 to 50 mole percent of the at least one second alkoxy silane residue based on the total moles of polymer particles and wherein the polymer particles have an average particle size of less than 10 nm; and the coating composition having a pH of no more than 5.