Three-dimensional printing of hydrophobic materials in fumed silica suspension

A method comprising:

• forming a heterogenous mixture of hydrophobic fumed silica nanoparticles and mineral oil, the heterogenous mixture having a concentration of the hydrophobic fumed silica nanoparticles in the mineral oil of between about 2% (w/v) and about 8% (w/v);
• mixing the heterogeneous mixture of hydrophobic fumed silica nanoparticles and mineral oil to form a homogenous mixture in which the hydrophobic fumed silica nanoparticles are at least partially dispersed within the mineral oil;
• centrifuging the homogenous mixture to form a colloidal suspension of the hydrophobic fumed silica nanoparticles within the mineral oil;
• allowing the colloidal suspension of the hydrophobic fumed silica nanoparticles within the mineral oil to rest for greater than a minimum rest duration to stabilize the colloidal suspension and form a hydrophobic yield-stress support material;
• and
• disposing one or more volumes of a hydrophobic printing material into the hydrophobic yield-stress support material to form an intermediate article having particular dimensions and a particular form factor,
• wherein, during a time period following the disposing of the one or more volumes of the hydrophobic printing material into the hydrophobic yield-stress support material to form the intermediate article, the one or more volumes of the hydrophobic printing material are substantially immobilized in order to maintain the particular dimensions and the particular form factor of the intermediate article.

A method, comprising:

• mixing a mass of hydrophobic fumed silica nanoparticles having an average diameter of between about 5 nm and about 500 nm into a volume of mineral oil to form a homogeneous mixture, the homogeneous mixture having a hydrophobic fumed silica nanoparticle concentration in the mineral oil of between about 2% (w/v) and about 8% (w/v), wherein the mixing causes the hydrophobic fumed silica nanoparticles to become dispersed throughout the mineral oil, and wherein the mixing also causes a plurality of microbubbles to become trapped in the homogeneous mixture;
• centrifuging the homogenous mixture at between about 1,000 rotations per minute and about 5,000 rotations per minute for between about one minute and about 30 minutes to remove at least a portion of the plurality of microbubbles trapped in the homogeneous mixture, thereby forming a colloidal suspension of the hydrophobic fumed silica nanoparticles within the mineral oil;
• maintaining a temperature of the colloidal suspension at a temperature of between about 25 degrees Celsius to about 100 degrees Celsius for greater than a minimum rest duration to form a plurality of hydrophobic fumed silica aggregates having an average aggregate size of between about 100 nm and about 500 nm, the plurality of hydrophobic fumed silica aggregates being formed through aggregation of the hydrophobic fumed silica nanoparticles dispersed within the mineral oil in the colloidal suspension, thereby structurally stabilizing the colloidal suspension and forming a hydrophobic yield-stress support material;
• and
• disposing one or more volumes of a hydrophobic printing material into the hydrophobic yield-stress support material to form an intermediate article having particular dimensions and a particular form factor,
• wherein, during a time period following the disposing the one or more volumes of the hydrophobic printing material into the hydrophobic yield-stress support material to form the intermediate article, the particular dimensions and the particular form factor of the intermediate article are substantially maintained.