FT-IR analysis.
Figure 1 shows infrared spectra of CNC, CNC treated with HCl and CNC treated with NaOH. This Data suggests that there are no significant changes in the structure of CNC due to extreme acid and basic media exposition. All the major vibration modes remained unchanged, this included 3330 cm-1 broad band corresponding to OH stretching, 2890 cm-1 due to CH2 and CH asymmetric and symmetric stretching, 1638 cm-1 related to the bending mode of absorbed water, 1430 to 1330 regions corresponding to CH2 and CH bending, the sharp band around 1100 cm-1 due to C-O-C asymmetric stretching (β-glucosidic linkage) and C-O/C-C (ring) stretching. 895 cm-1 of the CH rocking mode and the broad band starting 730 cm-1 of the out-of-plane bending of …show more content…
Average diameter and Z-potential of 0.1% suspension of CNC and CNC treated with HCl and NaOH measured at pH 7.
Sample Z average (nm) α PDI α Z potential (mV) α
CNC 125.1 ±0.6 0.196 ± 0.007 -54 ± 1
CNC treated with HCl 343+4 0.278 ± 0.001 -33 ± 1
CNC treated with NaOH ------------ β ----------- β -32.7 ± 0.8 α Analysis was carried out in triplicate β PDI very high, sample not suitable for DLS
Scanning electron microscopy.
SEM micrographs of 0.1% suspensions of CNC showed homogeneous sphere-like particles with diameter about 100 nm dispersed in the carbon film of the holder (Figure 5A). This is expected due to electrostatic repulsion among nanoparticles in aqueous suspension before drying. In contrast, micrographs of CNC treated with HCl and NaOH Figure 5B and 5C respectively) evidenced agglomerated particles with sizes ranging micrometer. This was more evident in the case of CNC treated with NaOH, where it can observe flake-like structure with little or no homogeneity. This data are in good agreement with the DLS …show more content…
A closer look revealed that CNC structure contained cellulose I and cellulose II. Figure 7 shows the characteristic diffraction peaks at 2θ angles of around 14.9º, 16.5º, 22.5º and 34.5º assigned to the typical reflection planes of cellulose I: 1-10, 110, 200 and 0.04, respectively. In addition to that, diffraction peaks at 2θ: 12.2º, 20.2º corresponding to reflection planes of cellulose II: 1-10 and 110, respectively are presented3-4. Cellulose I is the most prevalent form in the nature and it occurs in two allomorphs Iα and Iβ. Cellulose II is the crystalline form that emerges after re-crystallization or mercerization with aqueous sodium hydroxide, and it is thermodynamically the most stable form. In cellulose I the chain orientation is exclusively parallel, whereas in cellulose II the chains are arranged in an antiparallel orientation.1, 5. Since polymorphism is present in the CNC from stock, treatment with HCl or NaOH is not responsible for this structural feature, Instead, the production process should have the key to understand the particularity of this
Figure 1 shows infrared spectra of CNC, CNC treated with HCl and CNC treated with NaOH. This Data suggests that there are no significant changes in the structure of CNC due to extreme acid and basic media exposition. All the major vibration modes remained unchanged, this included 3330 cm-1 broad band corresponding to OH stretching, 2890 cm-1 due to CH2 and CH asymmetric and symmetric stretching, 1638 cm-1 related to the bending mode of absorbed water, 1430 to 1330 regions corresponding to CH2 and CH bending, the sharp band around 1100 cm-1 due to C-O-C asymmetric stretching (β-glucosidic linkage) and C-O/C-C (ring) stretching. 895 cm-1 of the CH rocking mode and the broad band starting 730 cm-1 of the out-of-plane bending of …show more content…
Average diameter and Z-potential of 0.1% suspension of CNC and CNC treated with HCl and NaOH measured at pH 7.
Sample Z average (nm) α PDI α Z potential (mV) α
CNC 125.1 ±0.6 0.196 ± 0.007 -54 ± 1
CNC treated with HCl 343+4 0.278 ± 0.001 -33 ± 1
CNC treated with NaOH ------------ β ----------- β -32.7 ± 0.8 α Analysis was carried out in triplicate β PDI very high, sample not suitable for DLS
Scanning electron microscopy.
SEM micrographs of 0.1% suspensions of CNC showed homogeneous sphere-like particles with diameter about 100 nm dispersed in the carbon film of the holder (Figure 5A). This is expected due to electrostatic repulsion among nanoparticles in aqueous suspension before drying. In contrast, micrographs of CNC treated with HCl and NaOH Figure 5B and 5C respectively) evidenced agglomerated particles with sizes ranging micrometer. This was more evident in the case of CNC treated with NaOH, where it can observe flake-like structure with little or no homogeneity. This data are in good agreement with the DLS …show more content…
A closer look revealed that CNC structure contained cellulose I and cellulose II. Figure 7 shows the characteristic diffraction peaks at 2θ angles of around 14.9º, 16.5º, 22.5º and 34.5º assigned to the typical reflection planes of cellulose I: 1-10, 110, 200 and 0.04, respectively. In addition to that, diffraction peaks at 2θ: 12.2º, 20.2º corresponding to reflection planes of cellulose II: 1-10 and 110, respectively are presented3-4. Cellulose I is the most prevalent form in the nature and it occurs in two allomorphs Iα and Iβ. Cellulose II is the crystalline form that emerges after re-crystallization or mercerization with aqueous sodium hydroxide, and it is thermodynamically the most stable form. In cellulose I the chain orientation is exclusively parallel, whereas in cellulose II the chains are arranged in an antiparallel orientation.1, 5. Since polymorphism is present in the CNC from stock, treatment with HCl or NaOH is not responsible for this structural feature, Instead, the production process should have the key to understand the particularity of this