Degradation Mode of PBAT Mulching Film and Control Methods During Its Degradation Induction Period

: The plastic film plays an important role in China's agricultural production. However, the large-scale use of plastic film has also produced a very serious problem of agricultural film pollution. Biodegradable polymers have attracted much attention because of the environmental pollution caused by traditional plastic mulching film. The most typical one is poly (butylene adipate co butylene terephthalate, PBAT). Poly (Butylene Adipate-co-Terephthalate) (PBAT) is a kind of aliphatic–aromatic polyesters with excellent biodegradability and mechanical processing properties. Therefore, it has been rapidly developed and widely used in the industry. However, there are clear requirements for the degradation period of agricultural film. At present, the degradable materials available on the market are difficult to meet the requirements of all crops for their degradation period. In this paper, the basic properties，degradation process and ways to delay the degradation of PBAT are reviewed to improve the degradation period of plastic film prepared by using this kind of material. Among them, the degradation process includes photodegradation, biodegradation and hydrolysis. The ways to delay the degradation include adding chain extender, light stabilizer, anti-hydrolysis agent and antibacterial agent. These can provide a theoretical basis for the research and development of biodegradable film with controllable degradation cycle. The future research and development of biodegradable polymers mainly focus on controllable degradation rate, stable degradation cycle, new materials and reducing research and development costs.

Ultrafast Bulk Degradation of Polylactic Acid by Artificially Cultured Diatom Frustules

In the field of governing our “Plastic Planet”, polylactic acid (PLA) has been considered to be a promising and ecologically friendlier alternative to traditional petroleum-based plastics. However, PLA-based products degrade slowly in the natural environment, likely resulting in a large accumulation of PLA waste worldwide in the near future. Herein, we have incorporated artificially cultured diatom frustules (DFs) into PLA, and found an improvement of more than eightfold on the degradation rate, from more than 24 months to 3 months or even less, as compared with the pure PLA. Mechanistic investigations illustrate that DFs change the degradation behavior of PLA from surface erosion to bulk erosion by the induced microfibril crystals. Simulation analysis verifies that the unstable crack propagation inside the PLA matrix greatly accelerates the degradation. The method developed in this work provides an efficient way to achieve rapid and controllable degradation of biodegradable polymers for the urgent and widespread usage of green plastic productions.

Antimicrobial Activity and Degradation of Superhydrophobic Magnesium Substrates in Bacterial Media

The interest in magnesium-based materials is promoted by their biocompatibility, their bioresorbability, and their recently discovered antibacterial potential. Until now, the widespread use of magnesium alloys in different corrosive environments was inhibited by their weakly controllable degradation rate and poorly understood microbiologically induced corrosion behavior. To better understand the degradation and usability of magnesium-based alloys, in this study we have fabricated superhydrophobic coatings on a magnesium-based alloy, and analyzed the behavior of this alloy in bacterial dispersions of Pseudomonas aeruginosa and Klebsiella pneumoniae cells in phosphate-buffered saline. It was shown that the immersion of such coatings in bacterial dispersions causes notable changes in the morphology of the samples, dependent on the bacterial dispersion composition and the type of bacterial strain. The interaction of the superhydrophobic coatings with the bacterial dispersion caused the formation of biofilms and sodium polyphosphate films, which provided enhanced barrier properties in magnesium dissolution and hence in dispersion medium alkalization, eventually leading to the inhibition of magnesium substrate degradation. The electrochemical data obtained for superhydrophobic samples in continuous contact with corrosive bacterial dispersions for 48 h indicated a high level of anticorrosion protection.

Antimicrobial activity and degradation of superhydrophobic magnesium substrates in bacterial media

The interest in magnesium-based materials is promoted by their biocompatibility, bioresorbability, and by their recently found antibacterial potential. Until now the widespread use of magnesium alloys in different corrosive environments was inhibited by their weakly controllable degradation rate and poorly understood microbiologically induced corrosion behavior. To better understand the degradation and usability of magnesium-based alloys, in this study we have fabricated the superhydrophobic coatings on top of magnesium-based alloy and analyzed the behavior of this alloy in bacterial dispersions of Pseudomonas aeruginosa and Klebsiella pneumoniae cells in phosphate buffered saline. It was shown that immersion of such coatings into bacterial dispersions causes notable changes in the morphology of the samples, dependent on the bacterial dispersion composition and the type of bacterial strain. The interaction of superhydrophobic coatings with the bacterial dispersion caused the formation of biofilms and sodium polyphosphate films, which provided enhanced barrier properties for magnesium dissolution and hence for dispersion medium alkalization, eventually leading to inhibition of magnesium substrate degradation. Electrochemical data obtained for superhydrophobic samples continuously contacted with the corrosive bacterial dispersions during 48 h indicated a high level of anti-corrosion protection.

ROS-responsive organosilica nanocarrier for targeting-delivery of metformin against cancer with synergistic effect of hypoglycemia

The controllable degradation of silica nanoparticles in anticancer therapy remains challenging. Here, we offer the first report that thioketal (TK)-bond-containing bridge-organoakloxysilane has been synthesized. This allows for the fabrication of...