# US 12,594,728 B2 · Three-dimensional printing of hydrophobic materials in fumed silica suspension > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,594,728 B2 - Document ID: US12594728B2 - Status: Granted - Kind: B2 - Application number: 18/400,673 - Filed: 2023-12-29 - Published: 2024-08-15 - Granted: 2026-04-07 - Earliest claimed: 2018-12-21 - Assignees: University of Florida Research Foundation, Inc. - Applicants: University of Florida Research Foundation, Incorporated - Inventors: Yong Huang; Yifei Jin; Nevada J. Gellermann; Kaidong Song - Web page: https://patentgrep.com/patent/US12594728B2 ## CPC - B29C 64/40: Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof - B33Y 10/00: Processes of additive manufacturing - B33Y 70/00: Materials specially adapted for additive manufacturing - C08K 3/36: Silica - C08L 83/04: Polysiloxanes - B29C 64/118: using filamentary material being melted, e.g. fused deposition modelling [FDM] - B29K 2063/00: Use of {EP, i.e.} epoxy resins {or derivatives thereof}, as moulding material - B29K 2083/00: Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as moulding material - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS ## Abstract A three-dimensional (3D) printing methodology is disclosed for freeform fabrication of hydrophobic structures without the use of printed support structures. The build material is directly printed in and supported by a fumed silica-containing yield-stress support bath to form an intermediate article in the support bath material. The intermediate article may be liquid or only partially solidified after being printed into the support bath material. The intermediate article is then heated or irradiated with ultraviolet radiation to initiate cross-linking to solidify the printed intermediate article, forming a finished article. ## Claims ### Claim 1 A method comprising: disposing a mass of hydrophobic fumed silica nanoparticles in a volume of a mineral oil to achieve a concentration of the hydrophobic fumed silica nanoparticles in the mineral oil of between about 2% (w/v) and about 8% (w/v) to form a heterogenous mixture; mixing the heterogenous mixture to form a homogenous mixture comprising the mass of hydrophobic fumed silica nanoparticles dispersed throughout the volume of the mineral oil; centrifuging the homogenous mixture comprising the mass of hydrophobic fumed silica nanoparticles dispersed throughout the volume of the mineral oil to form a hydrophobic yield-stress support material; and disposing a volume 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. ### Claim 2 (depends on 1) The method of claim 1, wherein the mixing the heterogenous mixture to form the homogenous mixture is carried out for between about 10 minutes and about 120 minutes. ### Claim 3 (depends on 1) The method of claim 1, wherein the centrifuging the homogenous mixture is carried out for between about one minute and about 30 minutes. ### Claim 4 (depends on 1) The method of claim 1, wherein a plurality of microbubbles trapped are initially trapped in the homogeneous mixture of hydrophobic fumed silica nanoparticles in the mineral oil, and wherein the centrifuging the homogenous mixture removes at least a portion of the microbubbles trapped in the homogenous mixture. ### Claim 5 (depends on 1) The method of claim 1, wherein the hydrophobic fumed silica nanoparticles have an average diameter of between about 5 nm and about 500 nm. ### Claim 6 (depends on 1) The method of claim 1, wherein a concentration of the hydrophobic fumed silica nanoparticles in the mineral oil is about 6% (w/v). ### Claim 7 (depends on 1) The method of claim 1, further comprising: allowing the homogenous mixture to age for greater than a day to form a stable colloidal suspension therein of the mass of hydrophobic fumed silica nanoparticles in the volume of the mineral oil. ### Claim 8 (depends on 7) The method of claim 7, wherein the centrifuging the homogenous mixture forms a plurality of fumed silica aggregates from the hydrophobic fumed silica nanoparticles dispersed in the mineral oil. ### Claim 9 (depends on 8) The method of claim 8, wherein the fumed silica aggregates have an average aggregate size of between about 100 nm and about 500 nm. ### Claim 10 (depends on 7) The method of claim 7, wherein the allowing the homogenous mixture to age for greater than a day comprises maintaining a temperature of the homogeneous mixture between about 25 degrees Celsius and about 100 degrees Celsius, and wherein, after the allowing the homogenous mixture to age, the plurality of fumed silica aggregates are structurally resistant to perturbations of the hydrophobic yield-stress support material. ### Claim 11 (depends on 1) The method of claim 1, wherein the centrifuging the homogenous mixture is carried out at a centrifugal speed of between about 1,000 rotations per minute (RPM) and about 5,000 RPM. ### Claim 12 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. ### Claim 13 (depends on 12) The method of claim 12, wherein the mixing the heterogenous mixture to form the homogenous mixture is carried out for between about 10 minutes and about 120 minutes. ### Claim 14 (depends on 12) The method of claim 12, wherein the centrifuging the homogenous mixture is carried out for between about 1 minute and about 30 minutes. ### Claim 15 (depends on 12) The method of claim 12, wherein the homogeneous mixture comprises a plurality of microbubbles trapped in the homogenous mixture of hydrophobic fumed silica nanoparticles in the mineral oil, and wherein the centrifuging the homogenous mixture removes at least a portion of the plurality of microbubbles trapped in the homogenous mixture. ### Claim 16 (depends on 12) The method of claim 12, wherein the hydrophobic fumed silica nanoparticles have an average diameter of between about 5 nm and about 500 nm. ### Claim 17 (depends on 12) The method of claim 12, wherein the concentration of the hydrophobic fumed silica nanoparticles in the mineral oil is about 6% (w/v). ### Claim 18 (depends on 12) The method of claim 12, wherein the forming the heterogenous mixture of hydrophobic fumed silica nanoparticles and mineral oil comprises disposing a mass of the hydrophobic fumed silica nanoparticles into a volume of the mineral oil to achieve the concentration of the hydrophobic fumed silica nanoparticles in the mineral oil of between about 2% (w/v) and about 8% (w/v). ### Claim 19 (depends on 12) The method of claim 12, wherein, the centrifuging the homogenous mixture causes formation of a plurality of fumed silica aggregates from the hydrophobic fumed silica nanoparticles dispersed in the mineral oil. ### Claim 20 (depends on 19) The method of claim 19, wherein the fumed silica aggregates have an average aggregate size of between about 100 nm and about 500 nm. ### Claim 21 (depends on 12) The method of claim 12, wherein the allowing the colloidal suspension of the hydrophobic fumed silica nanoparticles within the mineral oil to rest for greater than the minimum rest duration to stabilize the colloidal suspension and form the hydrophobic yield-stress support material is performed for greater than about one hour while the colloidal suspension is maintained a temperature between about 25 degrees Celsius to about 100 degrees Celsius. ### Claim 22 (depends on 12) The method of claim 12, wherein the centrifuging the homogenous mixture is carried out at a centrifugal speed of between about 1,000 rotations per minute (RPM) and about 5,000 RPM. ### Claim 23 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. ### Claim 24 (depends on 1) The method of claim 1, wherein, during a time period following the disposing the volume 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. ### Claim 25 (depends on 1) The method of claim 1, wherein the disposing the one or more volumes of the hydrophobic printing material into the hydrophobic yield-stress support material is carried out using one or more nozzles moving along a predefined pathway through the hydrophobic yield-stress support material. ### Claim 26 (depends on 12) The method of claim 12, wherein the disposing the one or more volumes of the hydrophobic printing material into the hydrophobic yield-stress support material is carried out using one or more nozzles moving along a predefined pathway through the hydrophobic yield-stress support material. ### Claim 27 (depends on 23) The method of claim 23, wherein the disposing the one or more volumes of the hydrophobic printing material into the hydrophobic yield-stress support material is carried out using one or more nozzles moving along a predefined pathway through the hydrophobic yield-stress support material.