# In Situ and Partial In Situ Synthesis of Cellulose Magnetic/Maghemite Composites
## 2 Materials and Methods
### Equipment and Methods  
The ultrasonication experiments were performed with an ultrasonic generator, Sonics Vibracell, at 750 W nominal electric power and 20 kHz ultrasound frequency, provided with a display providing the energy delivered to the end of the probe and a sensor for temperature. The samples were dried in a Trade Raypa vacuum oven at 40 \({}^{\circ}\)C. The resulting powder was centrifuged in an Eba 21 Hettich Zentrifugen centrifuge at 4000 revolutions per minute. The structures of the precursors and the composites were investigated by FTIR spectroscopy on potassium bromide pellets by using a Bruker Vertex 70 spectrometer (2 cm\({}^{-1}\) resolution) and by X-ray diffraction (XRD) performed on a Rigaku Miniflex 600 diffractometer using CuK\(\alpha\) emission in the angular range of 2-90\({}^{\circ}\) (20). The scanning step was 0.01\({}^{\circ}\), and the recording rate was 2\({}^{\circ}\) per minute. The crystallinity index (Cr.I.) of cellulose was determined using the peak height method with the equation [8]:  
\[\mathrm{Cr.I.}=\frac{\mathrm{I_{002}-I_{am}}}{\mathrm{I_{002}}}\times 100 \tag{1}\] \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Total Time of Ultra-** & **Cellulose Addition** & \begin{tabular}{c} **Sonication Time** \\ **After Cellulose** \\ **Addition [min]** \\ \end{tabular} & \
\begin{tabular}{c} **Total Energy** \\ **MESP** \\ **Addition [min]** \\ \end{tabular} &
\begin{tabular}{c} **Final** \\ **Temperature [\({}^{\circ}\)C]** \\ \end{tabular} \\ \hline CM\({}_{0}\) & 30 & t: 0 & 30 & 64.5 & 71 \\ CM\({}_{15}\) & 30 & t: 15 & 15 & 53.3 & 87 \\ \hline \hline \end{tabular}  
A simplified description of the syntheses is shown below in Schemes 1 and 2.  
\begin{tabular}{c} \\ \end{tabular}  
\end{table} 
Table 1: Samples and the terms of the synthesis. where I\({}_{200}\) is the intensity of the peak at the diffraction angle 20 of 22.7 \({}^{\circ}\)C (corresponding to the Miller plane (200) and is also called the crystalline peak) and I\({}_{\rm am}\) is the intensity of the peak at 18 \({}^{\circ}\)C (corresponding to the Miller plane (110) and is called the amorphous peak). The weight fraction [%] between cellulose and iron oxides (maghemite and magnetite) was determined using whole powder pattern fitting (WPPF--a program used in X-ray diffraction performed with the Rigaku Miniflex 600 diffractometer, which allows the quantitative measurement of the crystalline phases of the analyzed powder, in our case, cellulose, magnetite, and maghemite in percentages) and Rietveld analysis. In order to determine the empirical crystallinity index, or lateral order index (LOI), by using FTIR spectroscopy, the following equation was used [7]:  
\[\rm{LOI}=I_{1433}/I_{897} \tag{2}\]  
where I\({}_{1435}\) and I\({}_{899}\) are the intensity of the absorbance peaks, at 1435 and 899 cm\({}^{-1}\) wavenumbers. Total crystallinity index (TCI) was determined with Equation (3):  
\[\rm{TCI}=I_{1371}/I_{2899} \tag{3}\]  
where I\({}_{1371}\) and I\({}_{2899}\) are the intensity of the absorbance peaks at 1371 and 2899 cm\({}^{-1}\) wavenumbers. The hydrogen bond intensity (HBI) was established with the following ratio:  
\[\rm{HBI}=I_{3346}/I_{1321} \tag{4}\]  
Some of the characteristic spectral bands are quite sensitive to the crystalline structure in cellulose materials. Thus, the bands located at 1435 and 1371 cm\({}^{-1}\), and the one at 899 cm\({}^{-1}\), correspond to crystalline and amorphous domains, respectively. I\({}_{1435}\)/I\({}_{899}\) and I\({}_{1371}\)/I\({}_{2899}\) ratios (I is the intensity of the absorbance peak \(\approx\) 1 - intensity of the transmittance peak) were used to calculate the empirical crystalline index or lateral order index (LOI) and the total crystalline index (TCI), respectively. TCI is proportional to the crystallinity degree of cellulose, and LOI is correlated with the overall degree of order in the cellulose.