Mechanical Properties and Recyclability of Fiber Reinforced Polyester Composites

Fiber reinforced polymer composites (FRPs) are valuable construction materials owing to their strength, durability, and design flexibility; however, conventional FRPs utilize petroleum-based polymer matrices with limited recyclability. Furthermore, fiber reinforcements are made from nonrenewable feedstocks, through expensive and energy intensive processes, making recovery and reuse advantageous. Thus, FRPs that use biobased and degradable or reprocessable matrices would enable a more sustainable product, as both components can be recovered and reused. We previously developed a family of degradable and reprocessable cross-linked polyesters from bioderived cyclic esters (l-lactide, δ-valerolactone, and ε-caprolactone) copolymerized with a bis(1,3-dioxolan-4-one) cross-linker. We now incorporate these networks into FRPs and demonstrate degradability of the matrix into tartaric acid and oligomers, enabling recovery and reuse of the fiber reinforcement. Furthermore, the effect of varying comonomer structure, catalyst, reinforcement type, and lay-up method on mechanical properties of the resultant FRPs is explored. The FRPs produced have tensile strengths of up to 202 MPa and Young's moduli up to 25 GPa, promising evidence that sustainable FRPs can rival the mechanical properties of conventional high performance FRPs.

Nanofiber Scaffolds as Drug Delivery Systems Promoting Wound Healing

Nanofiber scaffolds have emerged as a revolutionary drug delivery platform for promoting wound healing, due to their unique properties, including high surface area, interconnected porosity, excellent breathability, and moisture absorption, as well as their spatial structure which mimics the extracellular matrix. However, the use of nanofibers to achieve controlled drug loading and release still presents many challenges, with ongoing research still exploring how to load drugs onto nanofiber scaffolds without loss of activity and how to control their release in a specific spatiotemporal manner. This comprehensive study systematically reviews the applications and recent advances related to drug-laden nanofiber scaffolds for skin-wound management. First, we introduce commonly used methods for nanofiber preparation, including electrostatic spinning, sol-gel, molecular self-assembly, thermally induced phase separation, and 3D-printing techniques. Next, we summarize the polymers used in the preparation of nanofibers and drug delivery methods utilizing nanofiber scaffolds. We then review the application of drug-loaded nanofiber scaffolds for wound healing, considering the different stages of wound healing in which the drug acts. Finally, we briefly describe stimulus-responsive drug delivery schemes for nanofiber scaffolds, as well as other exciting drug delivery systems.

Fabrication of Polymer/Graphene Biocomposites for Tissue Engineering

Graphene-based materials (GBM) are considered one of the 21st century’s most promising materials, as they are incredibly light, strong, thin and have remarkable electrical and thermal properties. As a result, over the past decade, their combination with a diverse range of synthetic polymers has been explored in tissue engineering (TE) and regenerative medicine (RM). In addition, a wide range of methods for fabricating polymer/GBM scaffolds have been reported. This review provides an overview of the most recent advances in polymer/GBM composite development and fabrication, focusing on methods such as electrospinning and additive manufacturing (AM). As a future outlook, this work stresses the need for more in vivo studies to validate polymer/GBM composite scaffolds for TE applications, and gives insight on their fabrication by state-of-the-art processing technologies.