Layered Structural PBAT Composite Foams for Efficient Electromagnetic Interference Shielding

The utilization of eco-friendly,lightweight,high-efficiency and high-absorbing electromagnetic interference(EMI)shielding composites is imperative in light of the worldwide promotion of sustainable manufacturing.In this work,magnetic poly(butyleneadipate-coterephthalate)(PBAT)microspheres were firstly synthesized via phase separation method,then PBAT composite foams with layered structure was constructed through the supercritical carbon dioxide foaming and scraping techniques.The merits of integrating ferroferric oxideloaded multi-walled carbon nanotubes(Fe3O4@MWCNTs)nanoparticles,a microcellular framework,and a highly conductive silver layer have been judiciously orchestrated within this distinctive layered configuration.Microwaves are consumed throughout the process of“absorption-reflection-reabsorption”as much as possible,which greatly declines the secondary radiation pollution.The biodegradable PBAT composite foams achieved an EMI shielding effectiveness of up to 68 dB and an absorptivity of 77%,and authenticated favorable stabilization after the tape adhesion experiment.

Bi-/multi-modal pore formation of PLGA/hydroxyapatite composite scaffolds by heterogeneous nucleation in supercritical CO_2 foaming

Scaffolds with multimodal pore structure are essential to cells differentiation and proliferation in bone tissue engineering. Bi-/multi-modal porous PLGA/hydroxyapatite composite scaffolds were prepared by supercritical C02 foaming in which hydroxyapatite acted as heterogeneous nucleation agent. Bimodal porous scaffolds were prepared under certain conditions, i.e. hydroxyapatite addition of 5%, depressurization rate of 0.3 MPa. min-1, soaking temperature of 55 ℃, and pressure of 9 MPa. And scaffolds presented specific structure of small pores （122 μM ± 66 μm） in the cellular walls of large pores （552 μm ±127 μm）. Furthermore, multimodal porous PLGA scaffolds with micro-pores （37 μM ± 11μM） were obtained at low soaking pressure of 7.5 MPa. The interconnected porosity of scaffolds ranged from （52.53 ± 2.69）% to （83.08±2.42）% by adjusting depressurization rate, while compression modulus satisfied the requirement of bone tissue engineering. Solvent-free CO2 foaming method is promising to fabricate bi-/multi-modal porous scaffolds in one step, and bioactive particles for osteogenesis could serve as nucleation agents.

Poly（L-lactide）-grafted Bioglass/Poly（lactide-co-glycolide） Scaffolds with Supercritical CO2 Foaming Reprocessing for Bone Tissue Engineering

The bioglass particles/poly（lactide-co-glycolide）（BG/PLGA） scaffold has been extensively explored for biomedical applications due to its excellent advantages of mechanical property and controllable degradation rate. In ottr previous studies, the BG nanoparticle sttrface-grafted with poly（L-lactide）（PLLA） could substantially improve the phase compatibility between the polymer matrix and the inorganic phase and the biocompatibility of the scaffolds. However, using the traditional preparation methods to prepare the composite scaffold can barely achieve a high po- rosity and porous connectivity. In this work, the PLLA-grafted bioglass/PLGA（g-BG/PLGA） scaffolds were prepared by supercritical carbon dioxide foaming（Sc-CO2） with before or after particulate leaching（PL） method（Sc-CO2-PL or PL-Sc-CO2 method, PL/Sc-CO2 methods） and their applications in bone replacement and tissue engineering were investigated. The porosities of the g-BG/PLGA scaffolds prepared by the PL/Sc-CO2 methods were higher than 90%, and their mechanical properties had similar values with human cancellous bone. The proliferations of osteoblasts on the scaffolds were dependent on different preparation methods. The PL/Sc-CO2 methods significantly increased the proliferations of the cells. Computed tomography（CT） three-dimensional（3D） reconstruction tomographies of the implantation study for repairing calvarium defects of rabbits demonstrated that the calvarium defects were almost completely filled by the osteotylus in PL/Sc-CO2 method group at 12 week post-surgery, while there was little callus formation in PL method group and untreated control group. These results indicate that the g-BG/PLGA scaffolds prepared by the PL/Sc-CO2 methods exhibit rapid mineralization and osteoconductivity and are the optimal composites for bone repair.