Flexible hybrid hydrogel composites from pharmaceutical gelatin waste: optimized for sustainable three-dimensional printing

This research aimed to create a sustainable, ecofriendly, and simple strategy for the production of three-dimensional (3D) printing feedstock and solve the issue regarding pharmaceutical waste management via upcycling. A flexible, rubber-like hydrogel composite was prepared using pharmaceutical gelatin waste (GW) as a biopolymer matrix, commercial white cement (WC) filler, and other functional additives. The hybrid composites with different compositions were investigated systematically for their mechanical, thermal, and morphological properties, as well as swelling ratio, disintegrability, extrudability, and printability with shape retention. The optimal balance between mechanical strength and flexibility, offering both durability and deformation tolerance, is obtained for the composite with sodium alginate at 10 parts per hundred of GW (phg) and 30 phg WC. Excluding hydroxyl-terminated PDMS from the composite system enhanced disintegrability and water solubility but marginally reduced flexibility and processability. The rheological properties of the developed composites were evaluated for their suitability in fused deposition modeling (FDM) additive manufacturing, revealing the influence of formulation variations on flow behavior. Printing experiments were then used to derive the range of processing parameters required for successful molten-state 3D printing using in-house equipment. This cost-effective waste repurposing strategy reduces dependence on petroleum-based virgin plastics, while its tunable water solubility potentially simplifies the postprocessing steps in 3D printing technology.