# Development of Inkjet Printable Formulations Based on Polyorganosilazane and Divinylbenzene
## 2 Materials and Methods
### Characterization  
The crosslinking behavior and the chemical composition of all samples were investigated by Fourier transform infrared (FT-IR) spectroscopy. A Bio-Rad FTS 3000 Excalibur spectrometer (Varian, East Palo Alto, CA, USA) was used to record the spectra of all samples within a wavenumber range of 4000 and 500 cm\({}^{-1}\) by averaging 32 scans at a resolution of 4 cm\({}^{-1}\). A doctor blade was used to apply the samples on a shiny etched silicon wafer, which was then measured in an uncured state, after UV irradiation and after pyrolysis. The pyrolysis process was carried out in a nitrogen atmosphere in a tube furnace at maximal temperature of 1100 \({}^{\circ}\)C, as the wafer is sensitive to higher temperatures. The temperature was kept at 1100 \({}^{\circ}\)C for 5 h and the heating rate was controlled to 1 K/min.  
Raman spectroscopy was performed by a confocal Raman microscope (WITec alpha300, WITec GmBH, Kroppach, Germany) using a 532 nm laser, which operated at 10 \(\pm\) 1 mW as the excitation source. Three measurements were performed by each thin layer sample. Background subtraction was done by WITec project. The D- and G-bands, relating to the sp\({}^{2}\)- and sp\({}^{3}\)-hybridized carbons were fitted according to Lorentz. The ratio of the D-band and G-band intensities \(I_{D}/I_{G}\) was determined by the amplitude of each band. For amorphous carbon, the graphitic cluster size \(L_{a}\) can be calculated as follows (1), according to [PERSON] and [PERSON] (1998), where \(C^{\prime}(\lambda)\) is a wavelength-dependent pre-factor (for \(\lambda\) = 532 nm, \(C^{\prime}(\lambda)\) = 0.0062 A\({}^{-2}\)).  
\[\frac{I_{D}}{I_{G}}=C^{\prime}(\lambda)\times L_{a}^{2} \tag{1}\]  
Thermogravimetric analysis (TGA) was carried out to evaluate the ceramic yield after the evaluation of the polymer to ceramic conversion. The TGA measurement of cured samples was conducted by using STA-409C (Netzsch Group GmbH &Co, Selb, Germany). A heating rate of 10 K/min was set to heat the cured samples up to 1100 \({}^{\circ}\)C in nitrogen atmosphere. The uncertainty of the measurement of the residual ceramic yield is around \(\pm\)2%.  
The viscosity measurements of the prepared inks were performed by a cone and plate rheometer (Bohlin CVO50, Malvern Panalytical, Malvern, United Kingdom), with a cone diameter of 60 mm, a cone inclination angle of 2\({}^{\circ}\) and agap size of 70 \(\upmu\)m as function of the shear rate (2-500 s\({}^{-1}\)) at 25 \({}^{\circ}\)C. The viscosity of each ink was measured three times. The experimental uncertainty for the viscosity is \(\pm\) 1 mPa-s.  
Surface tension and contact angle measurements of the inks were performed by Drop-Shape-Analysis (DSA 100, Kruss GmbH, Hamburg, Germany). Three measurements for each sample were performed for the surface tension and contact angle.  
The electrical conductivity of the ceramics was measured at room temperature by using a collinear four probe and a Keysight B1500A Semiconductor Device Analyzer (Keysight Technologies, Inc., Santa Rosa, CA, USA). The spacing between the contact pins was 2.25 mm. The measurement was made by passing a current between 1 \(\upmu\)A and 1 mA, depending on the sample, through the outer probes and measuring the respective voltage between the inner probes with a step between 0.01 and 0.1 mA in dependence of the sample.  
The ohmic resistance was calculated from the slope of the obtained data. The electrical resistivity \(\varrho\) was calculated from the obtained resistance \(R_{man}\) (2):  
\[\varrho=G\cdot R_{mean} \tag{2}\]  
where \(G=2\pi\)s, which is a geometric correction factor for semi-infinite volume. \(G\) is multiplied by an additional correction factor T\({}_{1}\)(t/s) dependent on the finite thickness t of the sample, which is tabulated in the literature [51]. The electrical conductivity \(\sigma\) is the inverse of \(\varrho\). The 4-point measurement was carried out on three specimens for each formulation. Each specimen was contacted and measured three times at different points.