A novel carbazole based bismaleimide monomer: Synthesis, characterization, thermal and optical properties

In this study, a novel bismaleimide monomer: Carbazole-Bismaleimide (Cz-BisMI) was introduced to the literature as a first. Cz-BisMI was synthesized by a catalytic cyclodehydration reaction of 3,6-bismalemic acid carbazole which is an intermediate product obtained by an imidization reaction of 3,6-diamino carbazole. Then, the chemical structure of Cz-BisMI was elucidated by FT-IR, 1H NMR, 13C NMR and LC-MS spectroscopies. The thermal properties of Cz-BisMI were investigated by DSC in comparison with a commercial bismaleimide monomer, 4,4-bismaleimidophenylmethane (DPM-BisMI). Cz-BisMI has a melting point of 192°C and also, the onset temperature of the exothermic curve was measured as 293°C. Furthermore, it was determined that Cz-BisMI has a 35.6 percent larger processing window than DPM-BisMI. The spin-coated films of Cz-BisMI showed a high refractive index in the range of 1.61 to 1.50 between 400 and 650 nm with good transparency of over 85%. On the other hand, a new poly(bismaleimide): P(Cz-BisMI)s containing carbazole units was prepared by the self-polymerization process of Cz-BisMI. P(Cz-BisMI)s showed a high thermal transition temperature of 356°C. In conclusion, Cz-BisMI is a viable choice as a bismaleimide monomer for the development of opto-electronic materials due to its enhanced optical properties and thermal behavior.

New perspectives on development of polysulfones/cellulose derivatives based ionic-exchange membranes: Dielectric response and hemocompatibility study

Due to the increasing need from the membrane technologies for diverse applications, development of new generation of materials with electroactive properties and significant impact on the future technological systems was imposed. An innovative way of designing the membrane materials with long-term stable hydrophilicity, enhanced workability, porosity, and good biocompatibility, has been adopted by blending of quaternized polysulfone (PSFQ) with a cellulose derivative (cellulose acetate phthalate, CAP). Moreover, the quaternization effect has significantly improved the electrical performances, in terms of the ionic conductivity, electron interactions, and dielectric properties, required by target applications, i.e., ionic-exchange membranes, IEMs. Results derived from dielectric spectroscopy confirm the enhanced dielectric quality, reflected by a low dielectric constant and dielectric loss at high frequency. Additionally, the relationship between the resulted dielectric properties and response at the blood-biomaterial interface, have confirmed their excellent performance, constituting the preliminary basis for future tests concerning their functionality as IEMs in hemodialysis.

Structure–property relationship of polyetherimide based on aromatic dianhydride and long alkyl chain containing aromatic diamines

A series of new poly(ether imide)s (PEIs) were synthesized from different commercially available dianhydrides like 3,3′,4,4′-benzophenonetetracarboxylic dianyhride (BTDA) and pyromellitic dianhydride (PMDA) and diamines like 1,4-bis(4-aminophenoxy)propane, 1,4-bis(4-aminophenoxy)butane, 1,4-bis(4-aminophenoxy)pentane, and 1,4-bis(4-aminophenoxy)hexane by a typical two-step polymerization method. The structure of the monomers and PEIs prepared were confirmed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance and carbon-13 nuclear magnetic resonance spectral analysis. Solubility of the PEIs was tested in various organic solvents. Thermal properties of the PEIs were investigated by thermogravimetric analysis and differential scanning calorimetry. The temperature corresponding to 5% ( T5%) and 10% ( T10%) weight loss are from 318°C to 418°C and from 380°C to 480°C, respectively. These PEIs exhibit glass transition temperature in the range of 195–245°C, very low water absorption (0.37–0.62%), and low dielectric constant (2.68–3.17) at 1 MHz. The PEIs film possessed good mechanical properties with tensile strength of 77–98 MPa, elongation at break of 8–13%, and tensile modulus of 1.5–2.2 GPa. These results imply that the synthesized PEIs are well suited to be used as dielectric materials. Based on these studies the structure–property relationships were established.