A method of bonding comprising: preparing a flowable adhesive composition, the preparing comprising surface modifying silica nanoparticles, the surface modifying comprising providing a surface modification mixture comprising (a) silica nanoparticles that have been 1) treated with a cation exchange resin to lower the pH between 2 and 3 and then 2) treated with ammonium hydroxide to increase the pH to 9 and 9.5; (b) a silane surface modifying agent having hydrolysable groups; (c) water, wherein the number of moles of water present in the mixture is greater than the number of moles of hydrolysable groups; and (d) an optional water-miscible solvent; heating the surface modification mixture to at least 50°C to form non-aggregated, surface-modified silica nanoparticles having surface-modifier covalently attached to the silica nanoparticles; forming a dispersion comprising the non-aggregated, surface-modified silica nanoparticles and an epoxy resin; removing ammonium hydroxide; removing at least most of the water and the optional water-miscible solvent; and adding a cationic photoinitiator after the removing step; positioning the adhesive composition between a first article and a second article; and curing the adhesive composition in the presence of actinic radiation to bond the first article to the second article. preparing a flowable adhesive composition, the preparing comprising surface modifying silica nanoparticles, the surface modifying comprising providing a surface modification mixture comprising (a) silica nanoparticles that have been 1) treated with a cation exchange resin to lower the pH between 2 and 3 and then 2) treated with ammonium hydroxide to increase the pH to 9 and 9.5; (b) a silane surface modifying agent having hydrolysable groups; (c) water, wherein the number of moles of water present in the mixture is greater than the number of moles of hydrolysable groups; and (d) an optional water-miscible solvent; heating the surface modification mixture to at least 50°C to form non-aggregated, surface-modified silica nanoparticles having surface-modifier covalently attached to the silica nanoparticles; forming a dispersion comprising the non-aggregated, surface-modified silica nanoparticles and an epoxy resin; removing ammonium hydroxide; removing at least most of the water and the optional water-miscible solvent; and adding a cationic photoinitiator after the removing step; providing a surface modification mixture comprising (a) silica nanoparticles that have been 1) treated with a cation exchange resin to lower the pH between 2 and 3 and then 2) treated with ammonium hydroxide to increase the pH to 9 and 9.5; (b) a silane surface modifying agent having hydrolysable groups; (c) water, wherein the number of moles of water present in the mixture is greater than the number of moles of hydrolysable groups; and (d) an optional water-miscible solvent; heating the surface modification mixture to at least 50°C to form non-aggregated, surface-modified silica nanoparticles having surface-modifier covalently attached to the silica nanoparticles; forming a dispersion comprising the non-aggregated, surface-modified silica nanoparticles and an epoxy resin; removing ammonium hydroxide; removing at least most of the water and the optional water-miscible solvent; and adding a cationic photoinitiator after the removing step; positioning the adhesive composition between a first article and a second article; and curing the adhesive composition in the presence of actinic radiation to bond the first article to the second article.