Polylactic acid (PLA): Properties, synthesis, and biomedical applications - A review of the literature

This comprehensive review is an in-depth analysis of polylactic acid (PLA), an increasingly important biopolymer due to its wide-ranging applications and sustainability features. PLA's physical, thermal, and mechanical properties are closely linked to its molecular distribution, mass, and stereochemistry, allowing it to exist in amorphous or semicrystalline states. The controlled polymerization of different optical monomers enables the creation of different types of PLA with distinct properties. To address PLA's inherent hardness limitation, researchers are exploring blends with stereo complexes like PLLA/PDLA, leading to improved mechanical and thermal properties. PLA's moldability supports its versatility in various forms, from nanoparticles to resorbable sutures. Focusing on composite materials, the review discusses the use of PLA in reinforcing synthetic and natural fibers to obtain composites, and in the production of micro- and nanoparticles. The incorporation of fibers, such as wood, cotton, and carbon-based synthetics, significantly influences the composite's mechanical properties. Additionally, the rise of nanoscale fillers, including clays and nanoparticles, has offered cost-effective solutions for enhanced material performance. Synthesis methods for PLA encompass direct polycondensation and ring opening, with the latter preferred due to improved control of polymerization. The degradation behavior of the polymer which, together with its biocompatible properties and eco-friendly production methods, makes PLA a potential material for biological applications. The innovative features, obtained by the bibliometric map generated with the VosViewer software from Scopus database, highlights the role of PLA in the biomedical field, in particular for tissue engineering by improving healing rates and, as well as for implants and prosthetics.