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Nano-composite films were developed between silver nanoparticles (Ag NPs) and a low-density polyethylene (LDPE) using master batches by melt extruding and melt compounding. The Ag/PE composite film showed decreased gas permeability, moisture permeability coefficient, the tear strength, the longitudinal and transverse elongation to that of commercial LDPE. Although stiffness increased at high Ag (40 ppm) concentration, but the longitudinal and transverse tensile strength enhance comparing with commercial PE. Light transmittance and haze were comparable. Both Nano-silver and composite films are effective against Escherichia coli (E. coli). Antibacterial activity of nano-silver for E. coli was determined by diameter of the inhibition zone and the minimum inhibitory concentration of nano-silver is detected by tube double dilution method reaching 15.63 ppm. The composite films are effective inhibition of E. coli at concentrations of 40 ppm Ag nanoparticles. Moreover, Nano-silver migration occurs in composite film. One-side migration was conducted to detect under three food simulants (3% acetic acid, 50% ethanol and distilled water) at three degree of temperature (25 °C, 40 °C and 70 °C) on different period of time (2, 4, 6, 8, 10 and 12 hours). These results indicated that the highest migration amount was obtained with 3% acetic acid following distilled water and finally 50% ethanol under same conditions. The migration level is dependent upon time and temperature and high migration time and temperature can enhance migration level. These findings demonstrate that nano-silver-containing polyethylene composite film may have a great potential for developing antibacterial and acid food packaging system.

The self-assembly of a nonionic triblock copolymer (F127) and a nonionic surfactant (HS15) has been investigated due to favorable changes in properties in their mixtures. The effect of the mixing ratio on the self-assembly process and on the structural stability of the mixtures was studied by coarse-grained molecular dynamic simulation (CGMD) and experimental measurements (transmission electron microscopy, dynamic light scattering measurement, drug loading stability analysis, and fluorescence spectroscopy measurement). The CGMD provided the information on self-assembly behavior. The microstructure and micellar stability are affected by different proportions of F127/HS15. Pure HS15 molecules (system I) can rapidly form stable aggregates driven by strong hydrophobic force, including two steps: the formation of seed clusters and the fusion of them. At low F127 ratio (system II), the self-assembly process is dynamic unstable, and a volatile “coil/cluster-like” aggregate is formed under the single “binding” effect. As the ratio of added F127 increase, such as system III, stable “lotus-seedpod-like” aggregates form under the double effects of “binding plus wrapping”. Its dynamic equilibrium can be achieved rapidly. The experimental results approved the assumption of “different mixing ratio with different structural stability” and even different loading stability of F127/HS15 systems for drugs with different log P, such as PUE and DTX, which means different loading area for them in the micellar systems at different mixing ratios because of less hydrophobic microdomains with the increase of F127 molecules.

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