Tailorable Piezoelectric Chain Morphology in Biocompatible Poly-l-lactide Induced by Melt-Based 3D Printing

Biobased and biodegradable poly-l-lactide (PLLA) stands out among piezoelectric polymers for its biocompatibility and environmental sustainability. Its piezoelectric response is closely related to the crystallinity and the alignment of polymer chains, which is conventionally obtained by drawing techniques. These are two-step processes with tight shape constraints, and the material technology implementation would strongly benefit from the demonstration of a single-step process capable of directly achieving tailored piezoelectric morphology in PLLA biopolymer from polymer melt. Fused deposition modeling (FDM) three-dimensional (3D) printing can play this role, directly achieving tailored piezoelectric morphology in PLLA biopolymer by the microscale control of molecular chain orientation through preparation parameters, such as 3D printing speed or bed temperature. The printing-crystal phase content and texture-piezoelectric property relationships are comprehensively presented, and the key 3D printing parameters to obtain optimized piezoelectric chain morphologies are defined. Results reveal melt-based 3D printing to be a suitable technique for manufacturing biocompatible PLLA piezoelectric platforms that are also biodegradable. A commercial PLLA (molecular weight of 160 kDa) has been used, with which a large shear piezoelectric coefficient (d 14 = 8.5 pC/N) was attained after optimized printing. Biocompatibility in vitro with murine L929 fibroblasts is confirmed for this specific material, opening its use not only for smart monitoring but also for biomedical applications, including tissue engineering.