Bacterial Degradation of Low-Density Polyethylene Preferentially Targets the Amorphous Regions of the Polymer.

Low-density polyethylene (LDPE) is among the most abundant synthetic plastics in the world, contributing significantly to the plastic waste accumulation problem. A variety of microorganisms, such as H16, LS46, and PA2361, can form biofilms on the surface of LDPE polymers and cause damage to the exterior structure. However, the damage is not extensive and complete degradation has not been achieved.

Lithium, Magnesium, and Zinc Centers N,N'-Chelated by an Amine-Amide Hybrid Ligand.

The synthesis and structure of lithium, magnesium, and zinc complexes ,'-chelated by a hybrid amine-amido ligand ([2-(MeNCH)CHNR], abbreviated as LR, where R = H, SiMe, or Bn) are reported. The reaction of the least sterically demanding LH with various magnesium sources gives the hexameric imide [LMg] () by the elimination of -butane from LHMgBu () or by the reaction of LHLi () with MeMgBr. [LH]Mg () is obtained through the addition of 0.

A library of new bifunctional alkenes obtained by a highly regiodivergent silylation of 1,5-hexadiene.

An efficient methodology for the synthesis of two groups of silicon-containing alkenes is reported. It includes a highly regioselective functionalization of 1,5-hexadiene through hydrosilylation and dehydrogenative silylation with organofunctional silanes and siloxanes. The established conditions enable selective monofunctionalization of 1,5-hexadiene regardless of the organosilicon modifier used as well as the type of functional group bonded to the silicon-based compound.

The Role of Solubility in Thermal Field-Flow Fractionation: A Revisited Theoretical Approach for Tuning the Separation of Chain Walking Polymerized Polyethylene.

The influence of the polymer solubility on the separation efficiency in thermal field-flow fractionation (ThFFF) was investigated for a polymer model system of differently branched chain walking polyethylenes in five different solvents, which were selected depending on their physical parameters. The understanding of polymer thermal diffusion has been elucidated using a revisited approach based on the latest thermal diffusion prediction model by Mes, Kok, and Tijssen combined with the Hansen solubility theory. Thereby, a significant improvement in the precision of the thermal diffusion prediction and the separation efficiency has been achieved by implementation of the temperature dependency on Hansen solubility parameters.

Impact of Hot-Melt Extrusion Processing Conditions on Physicochemical Properties of Amorphous Solid Dispersions Containing Thermally Labile Acrylic Copolymer.

For successful formulation of amorphous solid dispersions (ASDs) using hot-melt extrusion, it is imperative to understand the effect that heat and shear rate has on the physicochemical properties of the excipient. In this study, we investigated the influence of hot-melt extrusion parameters on solvent-free binary ASDs of ibuprofen (IBU), a model active pharmaceutical ingredient, in methacrylic acid-ethyl acrylate copolymer type A, 1:1, EUDRAGIT® L100-55 (EUD). To evaluate the impact of barrel temperature, screw speed, and residence time on EUD mass average molar mass and IBU release profile, size-exclusion chromatography and dissolution testing were used, respectively.

Polyolefins Formed by Chain Walking Catalysis-A Matter of Branching Density Only?

Recently developed chain walking (CW) catalysis is an elegant approach to produce materials with controllable structure and properties. However, there is still a lack in understanding of how the reaction mechanism influences the macromolecular structures. In this study, a series of dendritic polyethylenes (PE) synthesized by Pd-α-diimine-complex through CW catalysis (CWPE) is investigated by means of theory and experiment.

The addition of Grignard reagents to carbodiimides. The synthesis, structure and potential utilization of magnesium amidinates.

Direct synthesis of magnesium amidinates of the general formula [RNC(R1)NR]MgR2 has been performed from appropriate carbodimide and Grignard reagents (R = iPr, Cy, pTol; R1 = Me, nBu; R2 = nBu, Cl, I). Magnesium bisamidinates of the composition [RNC(R1)NR]2Mg(solvent)2 are accessible from [RNC(R1)NR]MgR2 and via the Schlenk-like equilibrium in coordinating solvents. The only isolated amidinatomagnesium halide, preserved in the dinuclear form of {[pTolNC(Me)N-pTol]Mg(THF)}2-μ-(THF)-μ-(Cl)2, has been obtained from the reaction of pTol-N[double bond, length as m-dash]C[double bond, length as m-dash]N-pTol with MeMgCl(THF)n in hexane.

High Temperature Quadruple-Detector Size Exclusion Chromatography for Topological Characterization of Polyethylene.

Modifying material properties in simple macromolecules such as polyethylene (PE) is achieved by different connection modes of ethylene monomers resulting in a plurality of possible topologies-from highly linear to dendritic species. However, the challenge still lies within the experimental identification of the topology and conformation of the isolated macromolecules because of their low solubility, which demands methods with specific solvents and high operating temperatures. Additionally, a separation technique has to be coupled to different detection methods to meet the specific demands of the respective characterization goal.

Anaerobic digestion of aliphatic polyesters.

Anaerobic processes for the treatment of plastic materials waste represent versatile and effective approach in environmental protection and solid waste management. In this work, anaerobic biodegradability of model aliphatic polyesters, poly(L-lactic acid) (PLA), and poly(ɛ-caprolactone) (PCL), in the form of powder and melt-pressed films with varying molar mass, was studied. Biogas production was explored in batch laboratory trials at 55 ± 1°C under a nitrogen atmosphere.

Li(+) Catalysis and Other New Methodologies for the Radical Polymerization of Less Activated Olefins.

After a brief survey of conventional radical polymerization of alkenes, we review their Li(+) catalyzed radical polymerization and their controlled radical polymerization. Emphasis is on homopolymerization, but related copolymerization of less activated monomers is mentioned as well.