Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
According to the invention, the preparation method of the one-dimensional magnetic assembly array comprises the following steps:
(1) jetting aqueous ink containing magnetic nanoparticles onto the surface of a substrate in an array form by an ink-jet printing method, wherein the receding angle of the surface of the substrate is 3-30 degrees; and
(2) and under the induction action of a magnetic field, drying and assembling the ink array printed on the surface of the substrate.
The concentration of the ink of the present invention reflects the number of particles within a droplet, determining the distance and interaction between the particles. The interparticle distances of the same concentration are also different due to the different spreading area within the droplets of the phase. Therefore, in the range of 3-30 degrees of the receding angle (RCA), the RCA is smaller, the spreading area of the liquid drop is small, and the smaller concentration can meet the requirement of the suction distance of the needed particles; and vice versa. In ultra-low concentration droplets, the interparticle forces are very weak and are not sufficient to attract their assembly. Increasing the drop concentration, adjacent particles assemble nearby. Further increasing the ink drop concentration, the attractive force between the dipoles is enough to attract all the particles to assemble into an assembly with single nanometer particle precision. When the ink droplets are too thick, on the one hand the droplets are not sufficient to take up assemblies larger than their spreading diameter, and on the other hand the short lines formed during assembly coalesce laterally. It is worth noting that the formation of single particle precision one-dimensional magnetic assemblies is guaranteed just as the printed ink droplets confine the particles in discrete droplets, so that the "head-to-head" assembly can occur before lateral coalescence by adjusting the concentration. Therefore, the invention prepares the single-particle precision one-dimensional assembly with different lengths by controlling the ink concentration in a certain range.
In the step (1), the content of the magnetic nanoparticles in the magnetic nanoparticle-based aqueous ink is 0.001 to 0.1% by weight. For example, any value in the range of 0.001%, 0.005%, 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, and any two of these values may be selected, and preferably 0.005% to 0.02%.
In the invention, the saturated magnetic moment refers to the magnetic moment of all atoms in an object under the action of an external magnetic field at a certain temperature and can be orderly arranged in a certain direction, and the total magnetic moment is the saturated magnetic moment at the temperature. According to the invention, the magnetic nanoparticles have a saturation moment of 30 to 90 emu/g. For example, any value from the range of 30emu/g, 40emu/g, 45emu/g, 50emu/g, 55emu/g, 60emu/g, 65emu/g, 70emu/g, 75emu/g, 80emu/g, 90emu/g and any two of these values may be selected, preferably 30-80 emu/g.
In the invention, the magnetic nanoparticles are a nanoscale magnetic material, have quantum size effect, surface effect, small-size effect, macroscopic quantum tunneling effect and the like, and have superparamagnetism, good magnetic conductivity, compatibility and the like. According to the invention, the magnetic nanoparticles have a particle size of 40-1000 nm. For example, any value in the range of 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 315nm, 350nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm and any two of these values may be selected, and preferably 100nm and 600nm are selected.
According to the invention, the magnetic component in the magnetic nanoparticles can be selected from ferroferric oxide, gamma-ferric oxide, cobalt ferrite, nickel ferrite, cobalt oxide or nickel oxide.
According to the invention, the magnetic nanoparticle-based aqueous ink contains a single-component, two-component or multi-component aqueous solvent with a boiling point of 100-300 ℃, and preferably the boiling point of 120-250 ℃.
Preferably, the one-component aqueous solvent is selected from ethylene glycol, propylene glycol, diethylene glycol, glycerol, dimethyl sulfoxide, N-methylpyrrolidone, N-dimethylacetamide, formamide or acetamide;
preferably, the two-component aqueous solvent is selected from two of water, ethylene glycol, propylene glycol, diethylene glycol, glycerol, dimethyl sulfoxide, N-methylpyrrolidone, N-dimethylacetamide, formamide and acetamide;
preferably, the multi-component aqueous solvent is selected from a plurality of water, ethylene glycol, propylene glycol, diethylene glycol, glycerol, dimethyl sulfoxide, N-methylpyrrolidone, N-dimethylacetamide, formamide and acetamide.
In the invention, the solvent with high boiling point and low surface tension is added, on one hand, the printing is facilitated for adjusting the viscosity and the surface tension of the ink, on the other hand, the volatilization speed is reduced, so that the particles in the liquid drop have enough time to complete the assembly, and the systematic research on the behavior of the tiny liquid drop under the induction of a magnetic field is facilitated.
According to a preferred embodiment of the present invention, the magnetic nanoparticles provided by the present invention are prepared by coating a hydrophilic polymer on the surface of the magnetic component by a hydrothermal method to obtain nanoparticles composed of micro-clusters, such structure can simultaneously ensure particle size, superparamagnetic property and hydrophilic property. The hydrophilic polymer can be selected from polyacrylamide, benzene sulfonic acid maleic anhydride copolymer, etc.
In a preferred embodiment, the present invention provides a method for preparing an aqueous ink containing magnetic nanoparticles, which comprises uniformly mixing magnetic nanoparticles with a dispersion solvent, and ultrasonically dispersing the obtained mixed solution at an ultrasonic frequency of 50-100W (for example, any value in a range formed by any two of these point values) for 5min-2h (for example, any value in a range formed by any two of these point values, 10min, 15min, 20min, 30min, 1h, 1.5h, 2 h), thereby achieving stable dispersion performance of the magnetic nanoparticles in water; and finally, removing impurities by using a filter with the filter membrane pore size of 2-20 μm (for example, any value in a range formed by 2 μm, 5 μm, 10 μm, 20 μm and any two of the values can be selected), thus obtaining the magnetic nanoparticle-based aqueous ink.
In the invention, an ultrasonic instrument KH3200B from Kunshan grass ultrasonic instrument Limited is adopted to carry out ultrasonic dispersion at an ultrasonic frequency of 50-100W.
In the present invention, the smoothness, cleanliness and uniformity of the substrate surface all have an effect on the contact angle. The receding angle is the contact angle between the liquid and the wetted or dewetting substrate, as is the advancing angle, and the receding angle is the dynamic contact angle, which is a measure of the extent of slippage on the substrate surface and also represents the capillary force during drying of a droplet on the substrate surface. According to the invention, in step (1), the receding angle of the base surface is 3 ° to 30 °, and for example, any value in the range of 3 °, 7.3 °, 10.7 °, 11.5 °, 12 °, 15.3 °, 15.9 °, 17.5 °, 22.0 °, 25.5 °, 28.8 °, 30 °, and any two of these values, preferably 7.3 ° to 28.8 °, may be selected.
In the step (1), the surface of the substrate may be untreated or may be modified by plasma sputtering or a silane coupling agent.
According to the invention, the gas used for plasma sputtering is selected from oxygen or air, the sputtering power is 5-50W, and the sputtering time is 10-50 s.
In the present invention, the surface of the substrate was treated by using an Ompus plasma science and technology Ltd, DT02S low temperature plasma processor.
According to the invention, the silane coupling agent modification is that the substrate is heated for 2 to 12 hours (for example, optionally 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours and any value in the range of any two of the point values, preferably 3 to 5 hours) in an oven with a silane coupling agent atmosphere at 80 to 120 ℃ (for example, optionally 80 ℃, 90 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃ and any value in the range of any two of the point values, preferably 115 ℃ to 120 ℃);
preferably, the silane coupling agent is selected from 3- (2, 3-glycidoxy) propyltrimethoxysilane or 3-mercaptopropyltrimethoxysilane.
According to the present invention, the substrate may be selected from the group consisting of a silicon wafer, a glass sheet, a quartz sheet, a mica sheet, a metal sheet (e.g., an aluminum sheet, a copper sheet, etc.) and a polymer sheet (e.g., a polyimide sheet, a polyethylene terephthalate sheet, etc.), preferably a silicon wafer, a quartz sheet or a mica sheet.
In step (1), the volume of the ink droplets ejected onto the substrate surface is 10 to 100pL, and for example, may be selected from any value in the range of 10pL, 20pL, 30pL, 40pL, 50pL, 60pL, 70pL, 80pL, 90pL, 100pL and any two of these point values, and preferably 10 to 40 pL.
In the present invention, ink-jet printing was performed with a 10pL head using a Dimatix 2800 ink-jet printer from Fujifilm corporation, japan, and ink droplets of different volumes were obtained by controlling the array pattern.
The preset array of the present invention can be obtained by computer software, and the gap of the preset array is 100-1000 μm, for example, any value in the range of 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm and any two of these values can be selected; preferably 100-300 μm.
In step (2), the magnetic field is a uniform magnetic field provided by an electromagnetic field or a ferromagnetic field, and the magnetic field strength is 50-500mT, for example, any value in the range of 50mT, 100mT, 200mT, 300mT, 400mT, 500mT and any two of these values can be selected, preferably 100mT and 400 mT.
In step (2), the conditions of the drying temperature and relative humidity in the magnetic field may be those conventional in the art as long as ice is not condensed, for example, the drying temperature is 5 to 25 ℃ and the relative humidity is 20 to 90%.
The invention also provides a one-dimensional magnetic assembly array prepared by the method.
The invention also provides the application of the one-dimensional magnetic assembly array in the fields of magnetic field induction, cell differentiation, heat generation modulation and anti-counterfeiting display.
The present invention will be described in detail with reference to specific examples, but the present invention is not limited thereto.
In the following examples, the test methods and raw materials are referred to as follows:
contact angle: the measurement was carried out by means of a contact angle meter, OCA20 from DataPhysics, Germany, using a glycol solution with a mass fraction of 80%.
Back off angle: the measurement was carried out by means of a DCAT 11 dynamic contact angle meter from DataPhysics, Germany, using a glycol solution with a mass fraction of 80%.
Magnetic nanoparticle saturation moment: measuring with superconducting quantum interferometer magnetometer, specifically placing magnetic dispersion liquid in packaged plastic shell, with maximum magnetic field intensity (H) of 106A/m, the measurement temperature is 300K.
Magnetic field strength: the measurement is carried out by adopting a PPMS-9 physical property test system of the American Quantum Design company.
The morphology characterization of the single-nanoparticle precision one-dimensional magnetic array: measured by a Scanning Electron Microscope (SEM) using S-4800, JEOL Ltd.
Atomic spatial resolution: measured using a Multimode 8 Atomic Force Microscope (AFM) from Bruker, Germany.
Magnetic gradient distribution: measured using a Multimode 8 Magnetic Force Microscope (MFM) from Bruker, Germany.
The room temperature means 23. + -. 2 ℃.
Preparing ferroferric oxide-benzenesulfonic acid Maran anhydride copolymer magnetic spheres: see J.Gao et al, One-stepSolvothermal Synthesis of high ply Water-soluble, novel Charge Tarelserparamagnetic Fe3O4Colloidal Nanocrystal Clusters.Nanoscale 2013,5,7026-7033.
Preparing zinc ferrite-polyacrylamide nano magnetic spheres: see W.Cheng et al, high way Water-solvent Superparaimaging ferromagnetic Spheres with Composition and size. chem.Eur.J.2010,16, 3608-phase 3612.
In the case where no particular mention is made, the starting materials used are commercially available products in which:
poly (styrenesulfonic acid maleic anhydride) sodium salt (PSSMA): Sigma-Aldrich, USA, Mw-20000.
3- (2, 3-Glycidoxy) Propyltrimethoxysilane (GPTS): fluorochem chemical Co., Ltd, UK;
n-Decyltrichlorosilane (DTCS): fluorochem chemical Co., Ltd, UK.