Synthesis of (polyethylene terephthalate/polyϵ-caprolactone) copolyesters

Characterization of Nanoprecipitated PET Nanoplastics by 1H NMR and Impact of Residual Ionic Surfactant on Viability of Human Primary Mononuclear Cells and Hemolysis of Erythrocytes

Manufactured nanoplastic particles (NPs) are indispensable for in vitro and in vivo testing and a health risk assessment of this emerging environmental contaminant is needed. The high surface area and inherent hydrophobicity of plastic materials makes the production of NPs devoid of any contaminants very challenging. In this study, we produced nanoprecipitated polyethylene terephthalate (PET) NPs (300 nm hydrodynamic diameter) with an overall yield of 0.76%. The presence of the ionic surfactant sodium dodecyl sulfate (SDS) was characterized by 1H NMR, where the relative ratio of NP/surfactant was monitored on the basis of the chemical shifts characteristic of PET and SDS. For a wide range of surfactant/NP ratios (17:100 to 1.2:100), the measured zeta potential changed from -42.10 to -34.93 mV, but with an NP concentration up to 100 μg/mL, no clear differences were observed in the cellular assays performed in protein-rich media on primary human cells. The remaining impurities contributed to the outcome of the biological assays applied in protein-free buffers, such as human red blood cell hemolysis. The presence of SDS increased the NP-induced hemolysis by 1.5% in protein-rich buffer and by 7.5% in protein-free buffer. As the size, shape, zeta potential, and contaminants of NPs may all be relevant parameters for the biological effects of NPs, the relative quantification of impurities exemplified in our work by the application of 1H NMR for PET NPs and the ionic surfactant SDS could be a valuable auxiliary method in the quality control of manufactured NPs.

Nude and Modified Electrospun Nanofibers, Application to Air Purification

Air transports several pollutants, including particulate matter (PM), which can produce cardiovascular and respiratory diseases. Thus, it is a challenge to control pollutant emissions before releasing them to the environment. Until now, filtration has been the most efficient processes for removing PM. Therefore, the electrospinning procedure has been applied to obtain membranes with a high filtration efficiency and low pressure drop. This review addressed the synthesis of polymers that are used for fabricating high-performance membranes by electrospinning to remove air pollutants. Then, the most influential parameters to produce electrospun membranes are indicated. The main results show that electrospun membranes are an excellent alternative to having air filters due to the versatility of the process, the capacity for controlling the fiber diameter, porosity, high filtration efficiency and low-pressure drop.

Room-temperature Barbier single-atom polymerization induced emission as a versatile approach for the utilization of monofunctional carboxylic acid resources

Barbier polymerization is realized at room-temperature with single-atom polymerization and polymerization-induced emission characteristics, which exhibits capability on sensitive explosive detection and artificial light-harvesting system fabrication.

Alicyclic polyesters from a bicyclic 1,3-dioxane-4-one

Ring-opening polymerisation of cyclopentyl-decorated dioxaneone rings accesses fully alicyclic polyesters through elimination of formaldehyde.

Thermoset elastomers covalently crosslinked by hard nanodomains of triblock copolymers derived from carvomenthide and lactide: tunable strength and hydrolytic degradability

Sustainable, mechanically reinforced, and hydrolytically degradable thermoset elastomers were synthesized by one-pot, three-step synthesis & crosslinking.

Low-Temperature Processable Degradable Polyesters

Block copolymers composed of a low-T(g) and high-T(g) block, with suitable pressure miscibility characteristics, can be formed at low-temperature through the application of pressure. Aliphatic block copolyesters composed of poly(ε-caprolactone) derivatives and poly(L-lactide) show room temperature processability under hydraulic pressure of 34.5 MPa without polymer degradation. Mechanism of the pressure-induced flow is investigated by small-angle X-ray scattering. A scattering associated with a lamellae structure observed at ambient conditions decreases with elevating hydrostatic pressures, indicating pressure-induced phase mixing. Traces of the pressure-induced phase transition are studied by differential scanning calorimetry and X-ray diffraction. Tensile test of the block copolymers reveals that the mechanical properties can be readily controlled by changing composition, molecular weight, and chemical structure of the blocks. Among them, the hard segment PLLA fraction is the key factor to characterize the properties. Young's modulus of the block copolyesters is similar to that of polyethylene.

Preparation of poly(butylene terephthalate)/modified organoclay nanocomposite via in-situ polymerization

Nanocomposites of poly(butylene terephthalate) (PBT)/modified montmorillonite organoclay were prepared via in-situ polymerization of terephthalic acid and butanediol in the presence of different clay content. Cloisite 30B, a commercially available amino modified montmorillonite, was modified with 3-aminopropytriethoxysilane (APS) through a silylation reaction. Morphology and properties of all samples were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1HNMR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The extent of clay layers in samples was confirmed by XRD. Results of XRD and TEM showed that an exfoliation structure was produced in nanocomposites. Studies of crystallization showed that the presence of nanoclay leads to an increase in the crystallization rate and enhances the thermal stability of nanocomposites. Crystallization kinetics were described by the Avrami equation. Crystal growth was spherulitic. According to dynamic mechanical analysis (DMA), storage modulus of nanocomposites was remarkably improved compared with homo PBT. Moreover, a shrinkage test was carried out. Results showed a reduction in shrinkages along and across the flow direction that means a decrease in free volume. Flammability based on the UL-94 test was applied to study the flame retardancy effect of nanoclay on the samples.

Organotin Compounds in Technology and Industry

Organotin compounds find a bigger range of technological and industrial applications than the organic compounds of any other metal. Many of these applications involve catalysis or anticatalysis, often in polymer chemistry, and they have an importance out of all proportion to the tonnage of tin which is used. This article reviews the present standing of the non-biological applications of organostannanes, with an emphasis on the mechanisms of the reactions which are involved.