Glycidyl methacrylate functionalized star-shaped polylactide for electron beam modification of polylactic acid: Synthesis, irradiation effects and microwave-resistant studies

A dual antioxidant and antimicrobial bioplastic film endowed with amine-branched poly(lactic acid): Bioactive packaging for electron beam sterilization and food shelf-life extension

Cyclic amine-multibranched poly(lactic acid) (mPLA) was prepared as a dual antioxidant and antimicrobial toward PLA active packaging for food shelf-life extension in a case study of bread. The mPLA was coupled with piperidine (PPR) containing a heterocyclic amine derivative, which is a nature-rich bioactive function. The functions of mPLA-PPR enhancing the PLA film performance were studied in comparison with PPR, mPLA and Tinuvin® 770. The mPLA-PPR promoted miscible nucleating action in the PLA film, and the elongation at break and ductility of PLA/mPLA-PPR were significantly improved with a resistivity against electron beam (EB) irradiation. The mPLA-PPR in the PLA film showed its antioxidation potential in both solution media and solid state. The PLA free radicals in solid-state created upon EB irradiation were efficiently stabilized by mPLA-PPR. The migration of PPR from the PLA matrix into food simulants was retarded when it was anchored on the mPLA. The PLA active film has antibacterial activity to inhibit the growth of E. coli and antimicrobial activity to inhibit expansion of natural molds on bread slices. This current study showed that the PLA/mPLA-PPR active film is a promising model of a functional bioplastic packaging for EB processed food sterilization and for food shelf-life extension.

Regio- and Stereoselective Construction of 1,3,5-Triaroylcyclohexanes via KOtBu-Mediated Cyclotrimerization of Aryl Vinyl Ketones

Herein, we disclose a simple one-pot method for an efficient regio- and stereoselective synthesis of 1,3,5-triaroylcyclohexanes from aryl vinyl ketones using potassium tert-butoxide. The developed protocol allows the construction of various symmetrically substituted cyclohexanes in good to excellent yields. The major product 2 also can be converted to the product 3 (all equatorial) conveniently by acid catalysis. This protocol features a good substrate scope and functional group compatibility.

Riboflavin as a Biodegradable Functional Additive for Thermoplastic Polymers

With continuous development of biodegradable polymers, new areas of applications are intensively researched. Modifications of these polymers are commonly conducted by an extrusion compounding process. While additives are changing desired properties, biodegradability of such composites can be deteriorated. The aim of the work is to investigate a novel, functional, organic additive, riboflavin (vitamin B-2), in terms of thermal stability, extrusion processability, wettability, surface energy, especially biodegradability, and when compounded with PLA. Additionally, a comparison of unmodified PLA resin, as well as PLA-modified with inorganic talc—which is known for its nucleation promotion in a variety of polymers—to PLA with riboflavin, was presented. Research reveals the outstanding thermal stability of riboflavin and the sufficient extrusion process properties with no significant changes of wettability and, surprisingly, a significant degradation rate as compared to pure PLA or and PLA with talc. The obtained results do not exclude further modifications of PLA depending on the target application, e.g., antimicrobial agents, flame retardants, etc.

Recent progress of preparation of branched poly(lactic acid) and its application in the modification of polylactic acid materials

Poly (lactic acid) (PLA) with branched structure has abundant terminal groups, high melt strength, good rheological properties, and excellent processability; it is a new research and application direction of PLA materials. This study mainly summarizes the molecular structure design, preparation methods, basic properties of branched PLA, and its application in modified PLA materials. The structure and properties of branched PLA prepared by ring-opening polymerization of monomer, functional group polycondensation, and chain extender in the processing process were introduced. The research progress of in situ formation of branched PLA by initiators, multifunctional monomers/additives through dynamic vulcanization, and irradiation induction was described. The effect of branched PLA on the structure and properties of linear PLA materials was analyzed. The role of branched PLA in improving the crystallization behavior, phase morphology, foaming properties, and mechanical properties of linear PLA materials was discussed. At the same time, its research progress in biomedicine and tissue engineering was analyzed. Branched PLA has excellent compatibility with PLA, which has important research value in regulating the structure and properties of PLA materials.