| Autor: |
Karyappa R; Digital Manufacturing and Design Centre, Singapore University of Technology and Design, 8, Somapah Road, Singapore 487372, Republic of Singapore. hashimoto@sutd.edu.sg.; Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Republic of Singapore., Nagaraju N; Digital Manufacturing and Design Centre, Singapore University of Technology and Design, 8, Somapah Road, Singapore 487372, Republic of Singapore. hashimoto@sutd.edu.sg.; Pillar of Engineering Product Development, Singapore University of Technology and Design, 8, Somapah Road, Singapore 487372, Republic of Singapore., Yamagishi K; Digital Manufacturing and Design Centre, Singapore University of Technology and Design, 8, Somapah Road, Singapore 487372, Republic of Singapore. hashimoto@sutd.edu.sg., Koh XQ; Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Republic of Singapore., Zhu Q; Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Republic of Singapore.; School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Republic of Singapore.; Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), Agency for Science, Technology and Research (A*STAR), 1 Pesek Road, Jurong Island, Singapore 627833, Republic of Singapore., Hashimoto M; Digital Manufacturing and Design Centre, Singapore University of Technology and Design, 8, Somapah Road, Singapore 487372, Republic of Singapore. hashimoto@sutd.edu.sg.; Pillar of Engineering Product Development, Singapore University of Technology and Design, 8, Somapah Road, Singapore 487372, Republic of Singapore. |
| Abstrakt: |
The synthesis of PVA hydrogels (PVA-Hy) requires a highly basic environment ( e.g. , an aqueous solution of sodium hydroxide, NaOH, 14% w/w, 4.2 M), but the rapid crosslinking of PVA due to high pH makes it challenging to perform layer-by-layer three-dimensional (3D) printing of PVA-Hy. This work demonstrated 3D printing of PVA-Hy in moderate alkaline conditions ( e.g. , NaOH, 1% w/w, 0.3 M) assisted by aqueous two-phase system (ATPS). Salting out of PVA to form ATPS allowed temporal shape retention of a 3D-printed PVA structure while it was physically crosslinked in moderate alkaline conditions. Crucially, the layer-to-layer adhesion of PVA was facilitated by delayed crosslinking of PVA that required additional reaction time and overlapping between the layers. To verify this principle, we studied the feasibility of direct ink write (DIW) 3D printing of PVA inks (5-25% w/w, μ = 0.1-20 Pa s, and MW = 22 000 and 74 800) in aqueous embedding media offering three distinct chemical environments: (1) salts for salting out ( e.g. , Na 2 SO 4 ), (2) alkali hydroxides for physical crosslinking ( e.g. , NaOH), and (3) a mixture of salt and alkali hydroxide. Our study suggested the feasibility of 3D-printed PVA-Hy using the mixture of salt and alkali hydroxide, demonstrating a unique concept of embedded 3D printing enabled by ATPS for temporary stabilization of the printed structures to facilitate 3D fabrication. |
