Role of Inorganic Fillers on the Physical Aging and Toughness Loss of PLLA/BaSO4 Composites

The addition of inorganic fillers has been reported to increase the toughness of poly(l-lactide) (PLLA), but the effect of physical aging in such composites has been neglected. The present work discusses the effect of the still ongoing segmental relaxation in PLLA-based composites filled with BaSO4 inorganic particles in regard of the filler quantity. By means of differential scanning calorimetry, X-ray diffraction, and tensile testing of progressively aged PLLA filled with particles ranging from 0.5–10 wt %, we observed an increase in the mechanical energy required to activate the plastic flow of the primary structure in the PLLA matrix, which resulted in the embrittlement of the majority of composites upon enough aging. Results further clarify the role of debonding in the activation process of PLLA, and the behavior of the composite is described at the segmental level. Only an addition of 10% of particles has effectively preserved a ductile behavior of the samples beyond 150 aging days; therefore, we strongly remark the significance of studying the effect of physical aging in such composites.The authors thank funding from the Basque Government (GV/EJ)-Department of Education, University and Research (consolidated research groups IT-1766-22 GIC21/131) and grant PID2019-106236 GB-I00 funded by MCIN/AEI/10.13039/501100011033 and PID2022-139821OB-I00 funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”. The Basque Government (GV/EJ) predoctoral grant for X.L. and SGIker technical services (UPV/EHU) for XRD and SEM support is also acknowledged

Benefits of Polydopamine as Particle/Matrix Interface in Polylactide/PD-BaSO4 Scaffolds

This work reports the versatility of polydopamine (PD) when applied as a particle coating in a composite of polylactide (PLA). Polydopamine was observed to increase the particle–matrix interface strength and facilitate the adsorption of drugs to the material surface. Here, barium sulfate radiopaque particles were functionalized with polydopamine and integrated into a polylactide matrix, leading to the formulation of a biodegradable and X-ray opaque material with enhanced mechanical properties. Polydopamine functionalized barium sulfate particles also facilitated the adsorption and release of the antibiotic levofloxacin. Analysis of the antibacterial capacity of these composites and the metabolic activity and proliferation of human dermal fibroblasts in vitro demonstrated that these materials are non-cytotoxic and can be 3D printed to formulate complex biocompatible materials for bone fixation devices.The authors express thanks for technical and human support provided by SGIker of UPV/EHU and European funding: European Regional Development Fund (ERDF) and European Social Fund (ESF)

Radiopaque Material for 3D Printing Scaffolds

The so called “Additive manufacturing” is a new manufacturing process which consists in translating virtual solid model data into physical models in a quick and easy process. The most known example is 3D printing. In the present work, this novel technology will be used to print scaffolds with biomaterials. Due to the problems that arise when controlling the clinical course of an implant, graft or polymer inside the human body, an innovative idea has emerged: it consists in incorporating particles of barium sulfate in order to increase the radiopacity of the polylactide (PLLA) and thus making these materials visible to X-rays. Accordingly, BaSO4 loaded PLLA composites were prepared via melt-blending and then injected for further characterization by thermal transitions, mechanical properties, morphology and radiopacity. X-ray analyses confirmed the enhanced radiopacity of the BaSO4 filled composites in comparison to their unfilled counterparts. It is demonstrated that the loads not only contribute to the material's radiopacity, but also dramatically improve its ductility. As an illustration, the incorporation of 10 wt.% of BaSO4 particles resulted in an outstanding 1647% and 3338% increase in toughness and elongation of PLLA matrix, respectively. In view of the good properties of these materials, they will be used for 3D printing. Through this technique it can be molded with any shape in a matter of minutes, making the use of this technology appealing for further innovations.Authors are thankful for funds of Basque Government (GV/EJ) Department of Education (IT-927-16) and from MINECO (MAT 2016-78527-P). N. Sadaba is thankful for the predoctoral fellowship to POLYMAT Fundazioa- Basque Center for Macromolecular Design and Engineering