Polymer Bulletin

Some parameters of propylene polymerization using δ-TiCl3/AlClEt2 and δ-TiCl3/AlEt3 catalyst systems were evaluated. The catalyst was prepared through the reduction of TiCl4 complexed with di-n-butyl ether (DBE) (mole ratio DBE/TiCl4=0.67) by AlClEt2. Propylene polymerizations were carried out at different Al/Ti ratios, using AlEt3 or AlClEt2 as cocatalysts and different polymerization temperatures. The effects of these parameters on catalyst activity, stereo-specificity and polymer molecular weight were investigated. The results indicate that these parameters strongly affect catalyst performance.

Recently, the green synthesizing methods of nanoparticles found their place in the center of attention. In this regard. the synthesis of useful nanoparticles such as the magnetic types, as well as the cases of Chia seeds that can form natural mucilage and function as a capping agent, are recognized of great importance. In this work, superparamagnetic (Fe3O4) nanoparticles were prepared by using the water extract of chia seeds for the first time, which was then coated with chitosan (CS), Fe3O4@CS core–shell, and finally, exerted for the drug delivery of oxaliplatin (OXA), and irinotecan (IRI) that were labeled as Fe3O4–OXA@CS core–shell and Fe3O4–IRI@CS core–shell, respectively. The nanoparticles were characterized through the means of XRD, FTIR, UV–Vis, TEM, FESEM, DLS, zeta potential, and VSM. The results of XRD analyses confirmed the successful synthesis of superparamagnetic nanoparticles. The observed crystallity, solid-phase, and hydrodynamic sizes were indicative of particle agglomeration in the solid phase, while in comparison to the crystallite sizes and particle diameters were increased up to more than 3-folds. The occurrence of agglomeration was more apparent in the case of Fe3O4–OXA@CS core–shell. Moreover, the cytotoxicities of nano-drugs were investigated against CT-26 cancer cells by the application of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The IC50 values of Fe3O4@CS core–shell, Fe3O4–OXA@CS core–shell, and Fe3O4–IRI@CS core–shell were reported to be 246.6, 79.6, and 61.1 ppm, respectively. The cytotoxicities of drug-loaded nanoparticles were exceedingly increased when being compared to the case of Fe3O4@CS core–shell.

Novel phenolic novolac resins, bearing phthalonitrile groups anchored to benzene ring through phenyl azo linkage were realized by the coupling reaction between novolac and phthalonitrile diazonium salt. The diazo-coupling occurred to a maximun of about 61%. The apparent molecular weight, determined form GPC showed a downward drift with increase in degree of phthalonitrile substitution. Analysis using DSC technique indicated that the resin underwent curing in a temperature range form 290 to 320 °C . The curing occurred via addition polymerization of phthalonitrile groups. The thermal stability and anaerobic char yield of the polymers increased proportion to the crosslinking. The probable cure mechanics were discussed.

The paper describes thermal and mechanical properties of a series of novel blends prepared using a two-stage process which invloved solution blending a specially-synthesised diacteylene-containing oligoester (DOE) with a semi-crystalline poly[ethylene-co-(vinyl acetate)] (EVA), followed by conversion of the DOE to a polydiacteylene-containing oligoester (cp-DOE) by in situ thermal cross-polymerisation during moulding. Moulded blends range from ductile to brittle materials and give intense Raman spectra in which the C≡C stretching band at ∼2100 cm-1 is well-defined and shifts to lower wavenumber when the blends are subjected to tensile stress. For each blend composition, shifts in wavenumber were used to determine local stress in the cp-DOE component independently of the overall stress applied to blend.

An original method has been developped which allows to study the influence of chain diffusion on the reaction kinetics in reactive polymer blends. Blends with controlled multilayer morphologies were directly prepared in a rotational rheometer and time-dependent dynamic mechanical measurements allowed to follow the progress of the reaction. Model miscible copolymers with different acrylic monomers were prepared for this study by controlling the composition, molecular weight and average number of reactive groups per chain. Reduced variables for the modulus and the reaction time were introduced to compare the results obtained for different concentrations of reactive groups. In comparison to homogeneous blends, the normalized results for the multilayered structures show that the extent of the reaction depends directly on the chain length and is thus controlled by chain diffusion.