Acetylated Distarch Phosphate/Chitosan Films Reinforced with Sodium Laurate‐Modified Nano‐TiO₂: Effects of Sodium Laurate Concentration

Abstract

Nano‐titanium dioxide (TiO2) was modified with the surfactant sodium laurate (SL) via ultrasonic microwave‐assisted technology to improve the dispersion of TiO2 in polymer matrices. As revealed by Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy analyses, SL was well adsorbed onto the TiO2 surface through chemical bonding, resulting in SL‐modified TiO2 (TiO2‐SLx). The hydrophobicity and dispersibility of TiO2‐SLx increased significantly compared to unmodified nano‐TiO2. With an increase in the SL concentration from 5% to 15%, the agglomeration of TiO2‐SLx particles decreased considerably, while the particles were more uniform. TiO2‐SLx nanoparticles (3 wt%) were then incorporated into acetylated distarch phosphate/chitosan (ADPS/CS) blended matrices to reinforce the biopolymers. Relative to unmodified TiO2, TiO2‐SLx exhibited a better dispersion capability. Furthermore, as the SL concentration increased, the tensile strength (TS) of the composite films increased, while the elongation at break (E), water vapor permeability (WVP), and solubility all decreased. The composite film containing TiO2‐SL15 (TiO2 modified with 15% SL; ADPS/CS‐TiO2‐SL15 film) displayed the highest TS (31.50 MPa), which was 33.70% higher than that of the pure ADPS/CS film, whereas the ADPS/CS‐TiO2‐SL25 film exhibited the lowest E. Further, the ADPS/CS‐TiO2‐SL15 film displayed the lowest WVP (0.90 × 10−12 g·cm−1·s−1·Pa−1) and solubility (22.91%), which decreased by 30.23% and 26.03% compared to that of the pure ADPS/CS film, respectively. Therefore, SL modification and the use of ultrasonic microwave‐assisted technology are promising for the preparation of nanofillers for biopolymer reinforcement. Practical Application Nano‐titanium dioxide (TiO2) nanoparticles were modified using the anionic surfactant sodium laurate via ultrasonic‐microwave assisted technology, to improve the dispersion of the TiO2 nanoparticles in polymer matrices. Modified TiO2 nanoparticles were incorporated into acetylated di‐starch phosphate/Chitosan blend films, causing the tensile strength of the composite film to increase and the water solubility and water vapor permeability of the composite film to decrease, making the films suitable for packaging applications.

Antifungal Effect of Chitosan/Nano-TiO2 Composite Coatings against Colletotrichum gloeosporioides, Cladosporium oxysporum and Penicillium steckii

“…Moreover, nano-TiO 2 has been particularly investigated due to its high tendency to form aggregates and, therefore, its low capacity to homogeneously disperse in organic media [ 9 ]. Researchers often use sodium dodecyl sulfate (SDS) [ 21 ], sodium laurate [ 22 ] and other surfactants to modify nano-TiO 2 particles to improve their dispersion in the carriers [ 23 ]. Maneerat and Hayata [ 24 ] evaluated the antifungal effect of TiO 2 in a coating film and found not only that the development of Penicillium rot in apples was significantly retarded by its photocatalytic reaction, but also that it decreased brown lesions and Penicillium rot infection in lemons.…”