Gity Mir Mohamad Sadeghi

Dual-function NIPUs with shape memory (shape recovery >90%) and self-healing capabilities (>92%) were synthesized. A solvent-free route utilizing commodity monomers was employed, combining semi-crystalline PCL domains with dynamic disulfide bonds.

In this article, the synthesis of four novel bioelastomers known as poly (xylitol sebacate) (PXS), poly (xylitol adipate) (PXA), poly (sorbitol sebacate) (PSS), and poly (sorbitol adipate) (PSA) was carried out through bulk polymerization, followed by their blending using the solution method. Six blends were prepared namely PXS25/PSS75, PXS50/PSS50, PXS75/PSS25, PXS50/PXA50, PSA50/PXA50, and PSS50/PSA50. After blending, a thermal curing process was applied to the samples. The intrinsic viscosity, density, T_g, hydrophilicity, degradation, wound healing, and mechanical properties of polymers and blends were measured to investigate the effects of blending. Analyzing hardness, modulus, stress at breakpoint, degradation, and hydrophilicity data showed that the mechanical properties of bioelastomers are adjustable by blending for tissue engineering. Furthermore, the scratch assay proved the biocompatibility of pure polymers and indicated that blending does not have a negative impact on this matter.

A hybrid thermo‐reversible crosslinking polyurethane nanocomposite containing 0.5, 1, and 2 wt.% of nano‐silica was prepared with three intrinsic self‐healing bonds (reversible covalent bonds supported by intrinsic hydrogen bonds and dangling chains). Owing to the introduction of pseudo‐tannin and polyester diol that could form phenol‐urethane networks and using nano‐silica that causes dangling chains and hydrogen bonds, the prepared polyurethanes are capable of being reversed at 110 °C and rejoin at low temperatures. Thermoset self‐healing polyurethane nanocomposites are prepared from pseudo‐tannin, nano‐silica, and a urethane‐based prepolymer. The investigations of chemical structure, self‐healing behavior, and cross‐link network are carried out by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) technique, and swelling test. dissociation of phenolic urethane at 110 °C was confirmed by temperature variable FTIR. By swelling test, it was found that the self‐healing polyurethane nanocomposites with 0.5 wt.% of nano‐silica have the most hard‐domain, gel content, and crosslink density in the samples. DSC technique shows that polyurethane samples have two heat transfer transitions (dangling chains and self‐healing). Thermogravimetric analysis (TGA) findings show that nanocomposites decompose at elevated temperatures than neat PU, and the rate of degradation diminishes as silica content increases.

In this research work, we synthesize a series of waterborne polyurethane (WPU) bio‐nanocomposite adhesives from bio‐based polyols, extracted from rapeseed cake residual (RCR) by oxypropylation procedure, and cellulose nanowhisker (CNW). The hydroxyl‐ (OH) number of the polyols, as the first variable parameter, is controlled through tuning oxypropylation degree by changing propylene oxide (PO) to RCR ratio. From the four prepared polyols, WPU of Polyol‐2 (WPU2) shows the most significant shear strength for wood and glass adhesion substrates. Polyurethane nanocomposites of CNW, with three different weight contents of 0.25, 0.50, and 1.0%, are prepared from WPU2, as the optimum WPU, and the WPU2 nanocomposite of WPU2‐0.50 wt% show the highest shear strength for all types of the substrates. For the WPU2 and WPU2‐0.50 wt% adhesives, the wood‐wood substrate show a high shear strength of 12.8 and 15.1 MPa, respectively. This work revealed that the shear strength of the adhesives and their failure mechanisms are affected by the structural parameters, OH‐number, and CNW content.

Acquiring a polymeric nanocomposite with biocompatibility, desirable dynamic‐mechanical‐thermal properties, and piezoelectricity, as well as high loading capacity, is challenging for design polymeric systems with potential applications in tissue engineering and biosensing. In this work, polyvinylidene fluoride (PVDF), poly(ε‐caprolactone) (PCL), and KIT‐6 mesoporous silica particles were used to prepare PVDF/PCL blends and their nanocomposites as potential candidates to meet the characteristics mentioned above. Hence, we deeply investigated the effect of the addition of PCL and KIT‐6 on the compatibility, crystallinity, and engineering properties of immiscible PVDF/PCL blends. PVDF/PCL blends without KIT‐6 particles and 75/25 PVDF/PCL blend containing various amounts of KIT‐6 particles were prepared by solution casting/annealing technique. It was found that PCL decreased the crystallization temperature and melting points of the PVDF component in the blends. The crystallinity and β‐phase content of PVDF reached maximum values for 75/25 PVDF/PCL blend; interestingly, KIT‐6 prevented PVDF crystallization and decreased β‐phase content. The results of thermogravimetric analysis and dynamic‐mechanical thermal analysis revealed that the presence of PCL reduced the thermal stability of the blends. On the other hand, KIT‐6 increased the thermal decomposition temperature and storage modulus of the polymeric matrix.