Impact on thermomechanical behaviour of a maleic anhydride grafted ABS on ABS/PC multi-layered blends

The significant increase of Waste Electric and Electronic Equipment (WEEE) has led to an important research in upgrading recycled engineering plastics by means of a blending technique. In particular, there is an interest in studying the properties of ABS/PC blends, the two most important components of WEEE, at ABS rich compositions, according to the generation ratio of waste [1]. Since ABS and PC are immiscible, the final properties depend to a large extent on the flow-induced morphology [2]. In order to better control the final blend morphology of injection molded samples, we propose a two-step approach: the first step consists in producing pellets with multilayered structure, using a multilayer coextrusion device. During the second subsequent step, the pellets are injection molded, with temperature conditions chosen to minimize the deformation of the created structures. The effect of a compatibilizer, namely, an ABS grafted with maleic anhydride (ABS-g-MA) [3] on the thermomechanical properties and morphology has been investigated

Chemoenzymatically synthesized ganglioside GM3 analogues with inhibitory effects on tumor cell growth and migration

Ganglioside GM3, belonging to glycosphingolipid family, has been known as tumor-associated carbohydrate antigen on several types of tumor. Many studies have revealed that GM3 plays a role in cell proliferation, adhesion and differentiation, which is crucial in the process of cancer development. In the present study, we firstly synthesized novel mannose-containing GM3 analogues by enzymatic hydrolysis and chemical procedures. Then the antiproliferative activity of the novel analogues along with galactose-containing analogues we prepared previously was investigated and the data demonstrated that these analogues exhibited antiproliferative effect on K562 and HCT116 cells. Finally, the influence of these analogues on tumor cell migration was studied on B16, B16-F10 and HCCLM3 cells by wound healing test, because the migration of tumor cells represents one of the relevant factors in assessing the malignancy of cancer. This study could lay the foundation for optimizing leading compounds and provide valuable information for finding new antitumor drugs for cancer therapy

Controlling the order of triblock copolymer via confinement induced by forced self-assembly

We report the making of multilayered self-assembled films by coextrusion, composed of alternated layers of confining polycarbonate and confined poly(styrene-. b-butadiene-. b-methyl methacrylate), whose blocks are chemically different from the confining polymer, and presenting a self-assembled morphology directly after extrusion. The triblock copolymer layers thicknesses was varied from few hundreds to few tens of nanometers. As the triblock layer thickness is decreased and the draw ratio is increased, the triblock morphology is constrained into a preferential orientation and higher long-range order is observed by transmission electron microscopy and small angle X-ray scattering. This one-step and industrially scalable method allowing long-range ordering of the nanodomains is of interest for many engineering applications for which producing large quantity of materials is necessary

From 1,4-Disaccharide to 1,3-Glycosyl Carbasugar : Synthesis of a Bespoke Inhibitor of Family GH99 Endo-α-mannosidase

Understanding the enzyme reaction mechanism can lead to the design of enzyme inhibitors. A Claisen rearrangement was used to allow conversion of an α-1,4-disaccharide into an α-1,3-linked glycosyl carbasugar to target the endo-α-mannosidase from the GH99 glycosidase family, which, unusually, is believed to act through a 1,2-anhydrosugar "epoxide" intermediate. Using NMR and X-ray crystallography, it is shown that glucosyl carbasugar α-aziridines can act as reasonably potent endo-α-mannosidase inhibitors, likely by virtue of their shape mimicry and the interactions of the aziridine nitrogen with the conserved catalytic acid/base of the enzyme active site

Crystallization behavior and morphological features of ethylene-vinyl alcohol 44 copolymer

This work is a first attempt to study the crystallization behavior of ethylene-vinyl alcohol copolymer with 44 mol% of ethylene units (EVOH44) and to observe the supermolecular structures developed during its crystallization. Thermal analysis has evidenced a very fast crystallization and the formation of different crystal populations during isothermal crys-tallization. In-situ wide-angle X-ray scattering experiments using a synchrotron radiation source have shown a unique or-thorhombic morphology, independently of the crystallization conditions. Small spherulites (with an average radius of about 1 µm) were observed using polarized optical microscopy and confirmed by typical four-leaf patterns obtained by small-angle light scattering. In-situ atomic force microscopy has revealed stacked lamellae growing from common centers to form small spherulitic entities. Finally, studies of isothermal crystallization have evidenced the existence of partial crystallization (especially at high crystallization temperatures) and the need for higher undercooling to complete crystallization. © BME-PT

An alternative radiolytic route for synthesizing conducting polymers in an organic solvent

A new and simple promising method for synthesizing conducting polymers in organic solvents was successfully achieved for the first time thanks to the oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) monomers dissolved in dichloromethane by means of gamma-radiolysis. The EDOT polymerization was controlled and optimized thanks to the study of the dose effect under an inert atmosphere. UV-Vis absorption spectroscopy was used to follow the polymerization process and to estimate both the radiolytic yield of EDOT oxidation and the required irradiation dose for quantitative poly(3,4-ethylenedioxythiophene) (PEDOT) preparation. Size exclusion chromatography (SEC) was used to determine the molar mass of the PEDOT polymers and thus their degree of polymerization. Polymers containing up to 20 EDOT units were detected. After deposition, ATR-FTIR spectroscopy and Energy-Dispersive X-ray (EDX) analysis highlighted the in situ doping of PEDOT polymers with chloride ions generated during dichloromethane radiolysis, while XRD analysis demonstrated the amorphous structure of the polymers. The morphology of the radiosynthesized PEDOT polymers was characterized in solution by Cryo-TEM microscopy and after deposition by SEM microscopy as well as by high-resolution AFM-IR microscopy coupled with infrared nanospectroscopy. In all cases, aggregated and packed spheroidal PEDOT particles with diameters comprising between 100 nm and 1.5 μm were observed. Besides, cyclic voltammetry (CV), four-point probe measurements and thermogravimetric analysis (TGA) showed that the PEDOT polymers radiosynthesized in dichloromethane are characterized by interesting electrical properties and good thermal stability. The present study bears witness to the tremendous potential of our radiation-based methodology and gives us a glimpse of future promising syntheses of different kinds of conducting polymers in organic solvents and even in complex matrices

Radiation-induced polymerization of 3-hexylthiophene in oxygen-free and oxygen-saturated dichloromethane solvent

We thank Jean-Michel Guigner (IMPMC, Université Pierre et Marie Curie, France) for Cryo-TEM experiments.As alternative radiolytic approach, the synthesis of P3HT was made possible thanks to the oxidation of 3HT monomers by chloromethyl and dichloromethyl radicals or by their corresponding peroxyl radicals in situ produced by dichloromethane solvent radiolysis. Under two different experimental conditions, in oxygen-free solution and in oxygen-saturated solution, two different polymers, “P3HTN2” and “P3HTO2” respectively, were successfully synthesized. Both produced materials were discerned by several analytical and spectroscopic techniques. UV–Vis absorption spectroscopy results showed that the radiolytic yield of 3HT oxidation in dichloromethane solvent is higher under O2 atmosphere. Indeed, a dose of 75 kGy was needed to polymerize 10 mM in 3HT under N2 atmosphere, meanwhile a dose of 35 kGy was sufficient to polymerize the same amount of 3HT under O2. The average molecular weight of P3HTO2was found higher than that of P3HTN2 as revealed by SEC chromatography analysis. Also, P3HTO2exhibits better thermal stability than P3HTN2. ATR-FTIR spectroscopy revealed the specific presence into P3HTO2 polymers of some functional groups such as carbonyl, hydroxyl and carboxyl moieties, which clearly explains the difference between the morphological structures of P3HTN2 and P3HTO2 as highlighted by cryo-TEM, SEM and AFM microscopies. Finally, both radio-synthesized P3HTN2 and P3HTO2 polymers were found characterized by remarkably significant conductive, electronic and optical properties

Contribution of shape and charge to the inhibition of a family GH99 endo-α-1,2-mannanase

[Image: see text] Inhibitor design incorporating features of the reaction coordinate and transition-state structure has emerged as a powerful approach for the development of enzyme inhibitors. Such inhibitors find use as mechanistic probes, chemical biology tools, and therapeutics. Endo-α-1,2-mannosidases and endo-α-1,2-mannanases, members of glycoside hydrolase family 99 (GH99), are interesting targets for inhibitor development as they play key roles in N-glycan maturation and microbiotal yeast mannan degradation, respectively. These enzymes are proposed to act via a 1,2-anhydrosugar “epoxide” mechanism that proceeds through an unusual conformational itinerary. Here, we explore how shape and charge contribute to binding of diverse inhibitors of these enzymes. We report the synthesis of neutral dideoxy, glucal and cyclohexenyl disaccharide inhibitors, their binding to GH99 endo-α-1,2-mannanases, and their structural analysis by X-ray crystallography. Quantum mechanical calculations of the free energy landscapes reveal how the neutral inhibitors provide shape but not charge mimicry of the proposed intermediate and transition state structures. Building upon the knowledge of shape and charge contributions to inhibition of family GH99 enzymes, we design and synthesize α-Man-1,3-noeuromycin, which is revealed to be the most potent inhibitor (K(D) 13 nM for Bacteroides xylanisolvens GH99 enzyme) of these enzymes yet reported. This work reveals how shape and charge mimicry of transition state features can enable the rational design of potent inhibitors