In this study, for the first time, we systematically investigate the effect of processing parameters on the size and alignment of electrospun PLGA fibers. We demonstrate that the alignment of the fibers has an impact on the release of encapsulated drug from these fibers.

Starch based scaffolds are considered as promising biomaterials for bone tissue engineering. In this study, a highly porous starch/polyvinyl alcohol (PVA) based nanocomposite scaffold with a gradient pore structure was made by incorporating different bio-additives, including citric acid, cellulose nanofibers, and hydroxyapatite (HA) nanoparticles. The scaffold was prepared by employing unidirectional and cryogenic freeze-casting and subsequently freeze-drying methods. Fourier transform infrared (FTIR) spectroscopy confirmed the cross-linking of starch and PVA molecules through multiple esterification phenomenon in presence of citric acid as a cross-linking agent. Field emission scanning electron microscopy (FE-SEM) observations showed formation of aligned lamellar pores with a gradient pore width in the range of 80 to 292 µm, which well meets the pore size requirement for bone regeneration, and also well dispersion of cellulose and HA nanofillers within the scaffold matrix. Based on the mechanical testing results, the cellulose-HA reinforced scaffold possesses sufficient compressive modulus and yield strength for non-load bearing applications in the dry state; and also it presents fast responsive shape recovery in the wet state. According to in-vitro assessments, apatite phase mineralization was extensively induced in the presence of HA nanoparticles as heterogeneous nucleating sites. Also, it was revealed that cellulose and HA nanofillers decelerate and accelerate the scaffold biodegradation rate, respectively. MTT assay proved good cytocompatibility of the nanocomposite scaffold with osteoblast cells. Finally, it was shown that the introduced scaffold provides a suitable platform for the cells adhesion.

Understanding the co-crystallization behavior of ternary polyethylene (PE) blends is a challenging task. Herein, in addition to co-crystallization behavior, the rheological and mechanical properties of melt compounded high density polyethylene (HDPE)/low density polyethylene (LDPE)/Zeigler − Natta linear low density polyethylene (ZN-LLDPE) blends have been studied in detail. The HDPE content of the blends was kept constant at 40 wt% and the LDPE/ZN-LLDPE ratio was varied from 0.5 to 2. Rheological measurements confirmed the melt miscibility of the entire blends. Study of the crystalline structure of the blends using DSC, wide angle X-ray scattering, small angle X-ray scattering and field emission SEM techniques revealed the formation of two distinct co-crystals in the blends. Fine LDPE/ZN-LLDPE co-crystals, named tie crystals, dispersed within the amorphous gallery between the coarse HDPE/ZN-LLDPE co-crystals were characterized for the first time in this study. It is shown that the tie crystals strengthen the amorphous gallery and play a major role in the mechanical performance of the blend.

Electrochemical devices that transform electrical energy to mechanical energy through an electrochemical process have numerous applications ranging from robotics and micropumps to microlenses and bioelectronics. To date, achievement of large deformation strains and fast responses remains challenging for electrochemical actuators wherein drag forces restrict the device motion and electrode materials/structures limit the ion transportation. Results for electrochemical actuators, electrochemical mass transfers, and electrochemical dynamics made from organic semiconductors (OSNTs) are reported. The OSNTs device exhibits high-performance with fast ion transport and accumulation in liquid and gel-polymer electrolytes. This device demonstrates an impressive performance, including low power consumption/ strain, a large deformation, fast response, and excellent actuation stability. This outstanding performance stems from the enormous effective surface area of nanotubes that facilitates ion transport and accumulation resulting in high electroactivity and durability. Experimental studies of motion and mass transport are utilized along with the theoretical analysis for a variable-mass system to establish the dynamics of the device and to introduce a modified form of Euler-Bernoulli's equation for the OSNTs. Ultimately, a state-of-theart miniaturized device composed of multiple microactuators for potential biomedical applications is demonstrated. This work provides new opportunities for next-generation actuators that can be utilized in artificial muscles and biomedical devices.

In this work, polyolefin-blend/clay nanocomposites based on low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and organically modified clay (OC) were prepared by melt extrusion. Various grades of maleic anhydride (MA) grafted polyethylene (PE-g-MA) were used and examined as compatibilizers in these nanocomposites. Differential scanning calorimetry analysis showed that OC and compatibilizer affect the crystallization behavior of LDPE/LLDPE with different mechanisms. Thermodynamic calculations of wetting coefficient based on interfacial energy between OC, LD, and LL, Morphological characterization based on field emission scanning electron microscopy, X-ray diffraction, small angles X-ray scattering, and dynamic rheology measurements revealed that the compatibilizer and OC were localized at the interface of LDPE and LLDPE phases with a preferred tendency toward one phase. Results demonstrated that at a specific amount of OC, there is an optimum compatibilizer concentration to achieve nanodispersed OC and beyond that the compatibilizer causes a structural change in the polymer crystalline morphology. It was also found that the tensile property enhancement of LDPE/LLDPE/OC nanocomposites is closely related to the crystalline structure development made by incorporation of both OC and compatibilizer.compatibilizer, crystalline morphology, immiscible polyolefin blend, organically modified nanoclay, polymer-clay nanocomposite | INTRODUCTIONPolymer/clay nanocomposite is created when the clay galleries containing silicate layers develop interfacial interactions with hosting polymers and are well dispersed in the polymer matrix. [1,2] As the pristine silicate layers are not able to provide such interactions in many polymer matrices, organically modified clays (OC) are necessarily employed in such nanocomposites. However, achieving nanostructured morphology is still problematic for nonpolar polymers like polyolefins even with OCs. [3][4][5] To promote the interfacial interaction between polyolefins and OC, suitable compatibilizers must be used. Effect of OC on the nucleation and crystal growth rate of