Chitosan/Clay Bionanocomposites: Structural, Antibacterial, Thermal and Swelling Properties

Abstract

In this study, Na + Montmorillonite (C Na), Nanoclay 1-135 (C 10A) and Nanoclay 1-140 (C 15A) were used as nanofiller in the preparation of chitosan biopolymer/clay nanocomposites. For this purpose, a dilute acetic acid solution was used as solvent for dissolving and dispersing the chitosan and the clays, respectively, and chitosan/C Na, chitosan/C 10A and chitosan/C 15A bionanocomposites were synthesized. Bionanocomposites were prepared by the solution induced intercalation method with various percentages of the three clay types. Then, the properties of the bionanocomposites were investigated as the loading of the clays was varied: 1%, 3%, 5%, and 7%. The characterization of the composites was done chemically by FTIR, physically by XRD and SEM, and thermally by TGA/DTA. Also, swelling tests of the clay and bionanocomposites were carried out. In addition, their antimicrobial properties were investigated towards Staphylococcus aureus and Escherichia coli. The highest antimicrobial activity was found for the chitosan/C 10A biocomposite. It was observed that the thermal stability of the bionanocomposites increased with increasing amount of clay added to chitosan. All the chitosan/clay biocomposites were observed by XRD and SEM, which revealed exfoliation behavior.

Synthesis, Characterization and Thermal Properties of Poly(MMA)/Organoclay Nanocomposites

“…Also, includes dimethyl benzyl alkyl chain quaternary ammonium chloride structures used in the modification. The following are the peaks from the chemical modifier; aliphatic N-CH3 vibration at 2840 cm -1 , aliphatic CH2 vibration at 1465 cm -1 , symmetric and asymmetric C-H stretching vibration at 2920 cm -1 and aromatic C=C stretching vibration at 1644 cm -1 [20]. The most characteristic bands observed for poly(MMA) units in nanocomposites are seen in (cm -1 ) 2850-3000 (aliphatic C-H), 1725 (C=O ester stretch), 1144 (C-O stretch-which is this frequency is quite variable) [22][23].…”

“…Materials Nanoclay 1-135 (C10A) was provided from Esan-Eczacıbaşı. The organic modifier of Nanoclay 1-135 is dimethyl, benzyl, hydrogenated tallow, quaternary ammonium cation with the particle size range of <15 μ, where tallow is ~65% C18, ~30% C16, ~5% C14 [20]. For nanocomposite synthesis, methyl methacrylate (MMA) as monomer, and benzoyl peroxide (BPO) (Aldrich) were used as initiator and 1,4-Dioxane and ethyl alcohol as solvent.…”

“…X-ray diffraction is the preliminary technique to verify whether the layered structure has altered or not. In the literature, the characteristic crystalline peaks of the diffraction angle of C10A organoclay was 2θ = 5.4°, 20°, 22° (d=1.64, 0.44, 0.40 nm) [20]. The distribution of the polymer between the layers of the clay causes that a clear XRD peak in the nanocomposites to be unreadable.…”

“…The distribution of the polymer between the layers of the clay causes that a clear XRD peak in the nanocomposites to be unreadable. The absence of component-specific peaks in nanocomposite materials can be explained by the fact that the polymer is intercalated between clay layers and clay layers become so irregular that they cannot give an XRD signal [20][21][22][23][24][25][26][27], therefore it can be considered as an exfoliated structure. Also, all peaks present in the XRD curve of the clays are not observed in the nanocomposites.…”

“…The nanodispersion of polymer molecules in silicate layers limits thermal movement, which increases thermal stability. It was observed that thermal stability of nanocomposites formed with clay increased with the increasing amount of clay in the composite, resulting in a clay thermal barrier [20][21][22][24][25][26][27]. The thermal properties of nanocomposites were determined by TGA/DTA/DTG simultaneous system.…”