Supporting information for: Inkjet Color Printing by Interference. Nanostructures

Transcription

1 Supporting information for: Inkjet Color Printing by Interference Nanostructures Aleksandr V. Yakovlev, Valentin. A. Milichko, Vladimir. V. Vinogradov, and Alexandr V. Vinogradov ITMO University, Saint-Petersburg, Russia A Materials The chemicals in this study were used as purchased: titanium (IV) isopropoxide (TTIP, 97%), nitric acid (HNO3, 65%). All reagents were purchased from Sigma-Aldrich. 96% ethanol was purchased from ChimMed, Russia. All aqueous solutions were prepared by using highly pure water from Millipore Elix (15 MOm/cm3). Soda-lime glass plates were used as substrates (microscope slides 26 mm x 76 mm, Paul Marienfeld, Germany). Substrates were sonicated in USI bath, rinsed with isopropanol, and dried in a flow of air. B Calculations of Z-numbers and rheological properties of inks Determination of ink compliance with inkjet printing was carried out by rheological parameters of TiO 2 ink, which are presented in Table S1. S1

2 12 ml of 2-Propanol 16 ml of Titanium isopropoxide Heat 70 o C Heat 80 o C 1 hour Solution #1 2-Propanol+ Titanium isopropoxide Solution #2 H 2 O+HNO 3 Aging in a sealed flask 1-2 weeks 0.7 ml HNO ml of DI water Diameter, nm Nanoparticle diameter, nm ζ-potencial ζ-potencial, mv 5 Stable TiO 2 sol TiO2 sol in Ethanol ratio, % 0 Figure S1: Outline of producing a nanocrystalline TiO 2 sol Figure S2: Diameter and zeta potential of nanoparticles vs. TiO 2 to ethanol ratio. Table S1: Summarized properties of printing solutions TiO 2 (sol)/ethanol, % Surface tension (mn/m) Viscosity (mp a s) Z-number ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± The parameter Z was calculated using the equation: Z = (d δ σ)/ν), where δ is the density, d is the diameter of the nozzle, σ is the surface tension, and ν is the viscosity of the reliability and sufficient dry mass content. S2

3 C Dynamic Light Scattering (DLS) Aggregation Measurements The measurements were carried out using a PhotoCor Compact-Z device. To this end, a dispersion of the materials under study was prepared (Figure S2 at page S2). D Inkjet printing Desktop office printer Canon Pixma IP2870 with standard cartridges PG-745, CL-746 was used in the experiments (Figure S3). The print head built into the cartridge has a droplet size of 2 pl and 1280 nozzles. After washing, the cartridge was filled with TiO 2 ink without any modification. The design of the printer and the cartridge remained unchanged. Viscosity was measured by a Brookfield HA / HB viscometer, and surface tension - with a Kyowa DY-700 tensiometer. a b c Figure S3: Preparing the printer: a - Canon PG-445 cartridge in its original state; b - Canon PG-445 cartridge with open lid and washed excipient; c - Canon Pixma IP2870 printer. E Inkjet printing fabrication For each picture two digital image copies (Figure S4) were created, which camouflaged the areas. These three layers of the image were printed sequentially. After completely drying S3

4 the first layer, second one was applied, and then by the same pattern the third one. Areas of layers containing black increased the thickness of the previously applied layer and produced a different color. Layer 1 Layer 2 Layer 3 Figure S4: Printed digital image layers. F SAED pattern Figure S5: SAED pattern of as-prepared TiO 2 nanoproducts. S4

5 Table S2: Anatase (TiO2) Phase Spot num. d-spacing (nm) Rec. Pos.(1/nm) Degrees to Spot 1 Degrees to x-axis Amplitude S5

6 G XRD X-ray powder patterns were obtained using a Bruker SMART Apex-II diffractometer operating with CuKα(λ = pm. Bruker Apex-II and EVA software were used for integration and data treatment. Figure S6: X-ray powder pattern of assynthesized TiO 2 nanoproducts with highlighted characteristic diffraction peak of anatase. Figure S7: X-ray powder pattern of anatase compared to amorphous phase Quantitative Analysis - Rietveld Phase 1 Anatase 98.8(57) %; Phase 2 Amorphous phase 1.2(57) %; Phase name Anatase Space group I41/amdZ Crystallite Size k: 0.89 LVol-FWHM (nm) 4.2(67) Lattice parameters a (Å) (49) c (Å) - 9.5(12) S6

7 H SEM images of layer surface The surface analysis was carried out using a scanning electron microscope (Magellan 400L). Visualization of relief and surface roughness are shown in Figure S8. Layer 1 Layer 2 Layer nm 200 nm 200 nm Figure S8: SEM images of TiO2 films for different layers When applying the first and second layers, film thickness was determined by SEM with sample cross-sections, since in reflected light measuring thickness was impossible due to the absence of spectrum coloration. Determination of the film thickness was carried out by EDS contrasting, as shown in Figures S7 and S8. Figure S9: Cross-section SEM and EDS image mapping of a TiO2 film with a thickness of 110 nm. Figure S10: Cross-section SEM and EDS image mapping of a TiO2 film with a thickness of 150 nm. S7

8 I Mechanical hardness TA.XTPlus texture analyzer (Stable Micro Systems, UK) operating with + Horizontal Friction System (A/HFS) was used to measure the shear strength for TiO 2 films with respect to a PET film. Mode: Option: Load Cell: Pre-Test Speed: Test Speed: Post-Test Speed: Distance: Count: Trigger Type: Trigger Distance: Tare Mode: Data Acquisition Rate: Measure Force in Tension Cycle Until Count 5 kg 1.0 mm/s 2.5 mm/s 2.5 mm/s 95mm 1 (can be increased for multiple cycling) Pre-travel 1.0mm Off 500pps Observations: The maximum peak force is the force required to initiate motion. The static coefficient of friction, s, can be calculated as follows: s = A s /B, (1) where: A s = initial force reading, g, and B = sled weight, g The fluctuations in the line may be a result of blooming which is not always uniform. The above curves were produced from the sled without addition of weights. The addition of weights is optional but will usually increase the magnitude of force measured and the stiction and frictional measurements are usually more distinctly different. The experimental technique was as follows. To determine the microhardness of TiO 2 layers, these were deposited on PET thin films, Fig. S10, and placed opposite each other. Hardness measurements implied some load applied to the film to start sliding. Detecting this value over time allows one to determine the static and dynamic friction coefficients. S8

9 Figure S11: Mechanism for measuring mechanical hardness of TiO 2 thin films on a PET substrate. J Characterization of highly refractive TiO 2 coatings To investigate optical properties of TiO 2 ink, films were coated from colloids on polished glass surface (microscope slides 26 mm x 76 mm, Paul Marienfeld, Germany) using Meyer rod (nickel wire with d = 10µm, thickness of applying a wet layer is 6 µm). After applying, the produced sol was dried at 60 C in the air for 15 minutes to form a thin layer of TiO 2. The operation was repeated several times to achieve the desired value of film thickness. Final coating thickness varied from 100 nm to 800 nm depending on the number of stages. Then, optical reflection measurement of TiO 2 films at normal incidence was carried out to obtain refractive indices. For this experiment the confocal optical scheme was arranged Figure S13. The incident unpolarized light from a halogen lamp (HL-2000-FHSA) was focused on the film surface through a 50x microscope objective (Mitutoyo M Plan APO, NA 0.55). Reflected light was collected through the same objective and then analyzed by a spectrometer (HORIBA LabRam HR) with a cooled CCD camera (Andor DU 420A-OE) and a 150 g/mm diffraction grating. The obtained spectra were normalized by the known spectrum of the halogen lamp. The reflectance spectra from different points of the film allowed us to estimate the error for refractive indices at various wavelengths. S9

10 Figure S12: Optical image of a TiO2 film deposited on glass vs. film thickness. Digit stands for the number of layers. a Figure S13: Reflectance spectroscopy setup for optical characterization of a TiO2 inkjet thin film. b o 60 40o o 20 0o R wavel engt h,nm Figure S14: a) Dependence of reflection of film on the angle of light incidence. The higher angle, the more colored the film. The thickness of the film is 630 nm. b) Comparison of the refractive properties of film deposited on fused silica and black substrate. The thickness of the film is 490 nm. S10

11 K Transmittance spectra The transmittance spectra of TiO 2 films deposited on the surface of an uncolored PET substrate were prepared using a Cary 8454 (Agilent Technologies) UV-Vis spectrophotometer with an adapted film holder. The transmittance spectra of the films are shown in Figure S Transmittance, % 60 PET Film 110 nm nm 260 nm 330 nm nm 510 nm 650 nm Wavelength, nm Figure S15: Transmittance spectra of TiO 2 films with different thickness. L Additional characterization The samples for transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) were prepared by dispersing small amounts of samples in ethanol to form a homogeneous suspension. A drop of the suspension was deposited on a carbon-coated copper grid for HRTEM observations (FEI TECNAI G2 F20 operating at 200 kv). Photographs of the samples were taken by the camera Nikon D800 with lens AF-S NIKKOR 24-70mm f/2.8g ED and AF-S NIKKOR mm f/2.8g ED VR II without using additional flash. The camera color calibration was performed using X-Rite ColorChecker Passport. S11