Iron oxide nanoparticle-based magnetic ink for additive manufacturing

Abstract

Embodiments of the present disclosure describe magnetic ink compositions, methods of making magnetic ink compositions, methods of printing magnetic ink compositions, magnetic substrates based on the magnetic ink compositions for microwave and/or RF devices, methods of making the microwave and/or RF devices, and the like.

What is claimed is: 
     
         1 . An ink composition, comprising:
 a plurality of magnetic iron oxide nanoparticles dispersed in a solution containing a carrier and a surface tension adjusting agent to form an iron oxide nanoparticle-based magnetic ink,   wherein a concentration of the magnetic iron oxide nanoparticles is about 10 wt %.   
     
     
         2 . The ink composition of  claim 1 , wherein the plurality of magnetic iron oxide nanoparticles include one or more of Fe 2 O 3  and Fe 3 O 4  nanoparticles. 
     
     
         3 . The ink composition of  claim 1 , wherein the plurality of magnetic iron oxide nanoparticles are characterized as one or more of superparamagnetic and ferromagnetic. 
     
     
         4 . The ink composition of  claim 1 , wherein the carrier is water or a water-compatible solvent. 
     
     
         5 . The ink composition of  claim 1 , wherein the surface tension adjusting agent is ethanol, methanol, propanol, Triton X-100, CTAB, or SDS. 
     
     
         6 . The ink composition of  claim 1 , wherein a viscosity is less than about 2 cP and/or a surface tension is less than about 45 mN m −1 . 
     
     
         7 . The ink composition of  claim 1 , wherein an average diameter of the Fe 3 O 4  nanoparticles ranges from about 15 nm to about 20 nm and/or a particle aggregate size is less than about 450 nm. 
     
     
         8 . A method of preparing an ink composition, comprising:
 mixing a carboxylic acid with an aqueous solution of an iron compound to form a mixture;   heating the mixture to or at a select temperature;   adding a base to the mixture upon reaching the select temperature to form magnetic iron oxide nanoparticles;   separating the magnetic iron oxide nanoparticles from one or more residual species; and   dispersing the magnetic iron oxide nanoparticles in deionized water to form an iron oxide nanoparticle-based magnetic ink.   
     
     
         9 . The method of  claim 8 , wherein the carboxylic acid includes one or more of acetic acid, carbonic acid, formic acid, propionic acid, butyric acid, pentanoic acid, and salts thereof. 
     
     
         10 . The method of  claim 8 , wherein the iron compound includes one or more of iron (II) chloride, iron (III) chloride, iron (II) fluoride, iron (III) fluoride, iron (II) bromide, iron (III) bromide, iron (II) iodide, iron (III) iodide, iron (II) nitrate, iron (III) nitrate, iron (II) acetate, iron (III) acetate, iron (II) sulfate, iron (III) sulfate, iron (II) oxalate, and iron (III) oxalate. 
     
     
         11 . The method of  claim 8 , wherein the select temperature is about 90° C. 
     
     
         12 . The method of  claim 8 , wherein the base includes one or more of metal hydroxides, metal oxides, metal alkoxides, ammonia, and derivatives thereof. 
     
     
         13 . The method of  claim 8 , wherein the base and carboxylic acid disassociate precipitates at about the select temperature for a formation of uniform and disperse iron oxide nanoparticles. 
     
     
         14 . The method of  claim 8 , wherein the one or more residual species includes one or more of the carboxylic acid and base. 
     
     
         15 . The method of  claim 8 , further comprising contacting the iron oxide nanoparticle-based magnetic ink with one or more alcohols to adjust a surface tension. 
     
     
         16 . The method of  claim 8 , further comprising filtering the iron oxide nanoparticle-based magnetic ink prior to jetting. 
     
     
         17 . The method of  claim 16 , wherein the filtering includes separating the iron oxide nanoparticle-based magnetic ink from particle aggregates greater than about 0.45 am. 
     
     
         18 . A method of printing a magnetic ink composition, comprising:
 printing a functionalized iron oxide nanoparticle-based magnetic ink composition containing functionalized magnetic iron oxide nanoparticles and a photocurable polymeric resin onto a removable substrate,   heating the printed magnetic ink composition to or at a select temperature for a select duration,   curing the printed magnetic ink composition sufficient to solidify the mixture; and   removing the removable substrate to provide a freestanding magnetic substrate.   
     
     
         19 . The method of  claim 18 , wherein the magnetic iron oxide nanoparticles include one or more of Fe 2 O 3  and Fe 3 O 4  nanoparticles. 
     
     
         20 . The method of  claim 18 , wherein the photocurable polymer resin is a UV-curable resin.