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Researchers Develop Tough Hydrogels for 3D Printing Applications in Repairing Load-Bearing Soft Tissues https://ift.tt/2U1O3uP The water-swollen polymer networks we know as hydrogels have many applications in the biomedical industry, but in order to use them to repair and regenerate load-bearing soft tissues, such as cartilage, blood vessels, and tendons, we need to create tougher biodegradable hydrogels. This is just what a collaborative team of researchers from the University of Twente, Utrecht University, and University Medical Center (UMC) Utrecht set out to do. ![]() Designed structure prepared from TPU-(PCL5-PEG10-PCL5) multi-block copolymer by fused deposition modelling: (a) Structure in the dry state and (b) comparison of the structure in dry and hydrated states. The researchers published a paper, titled “Thermoplastic PCL-b-PEG-b-PCL and HDI Polyurethanes for Extrusion-Based 3D-Printing of Tough Hydrogels,” that details their work in developing tough hydrogels based on the formation of thermoplastic polyurethanes (TPU), which have high toughness and can be processed through extrusion-based 3D printing processes. TPUs that are based on poly(ethylene glycol), or PEG, can be designed to form physical networks of hydrogels that take up a lot of water – perfect for working with load-bearing soft tissues.
![]() SEM images of 3D printed structures prepared from TPU-(PCL5-PEG10-PCL5) in the dry state at different magnifications. (a) overview of a printed structure, (b–d) images of the surface of the printed structure at higher magnifications. The tough hydrogels the team developed used a reaction of poly(ɛ-caprolactone)-b-poly(ethylene glycol)-b-poly(ɛ-caprolactone) triblock copolymers (PCL-b-PEG-b-PCL) and hexamethylene diisocyanate to form TPUs. In this multi-block copolymer, PEG will make the material hydrophilic, and the hydrophobic PCL component helps the structure fixate during 3D printing, as well as form the network’s crosslinks in the hydrated state.
Several tests and analyses, such as NMR-spectroscopy and Differential Scanning Calorimetry (DSC), were used to confirm the material’s chemical composition, structure, molar mass, and viscosity; tensile testing was also completed. Then, the team cut compression molded polymer films into small pieces and extruded them with a Noztek Pro filament extruder, before collecting the extruded filaments, air-cooling them, and using them to 3D print designed structures on an Ultimaker 2+ 3D printer at 1 mm per second. ![]() Synthesis of (a) hydroxyl-group terminated HO-PCL-b-PEG-b-PCL-OH triblock copolymers and (b) corresponding TPU-(PCL-b-PEG-b-PCL) thermoplastic polyurethane multi-block copolymers.
Co-authors of the paper are Aysun Güney, Christina Gardiner, Andrew McCormack, Jos Malda, and Dirk W. Grijpma. Discuss this research and other 3D printing topics at 3DPrintBoard.com or share your thoughts below. Printing via 3DPrint.com | The Voice of 3D Printing / Additive Manufacturing https://3dprint.com November 30, 2018 at 11:34AM
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