可直接3D列印之含纖維素奈米纖絲水性聚胺脂並於生物之應用

Abstract

作為一種新型的積層製造技術，3D列印技術在各個領域蓬勃發展。與傳統的製造技術不同，3D列印技術具有用戶自訂的特點，以此避免了高昂的模具。聚胺脂 (polyurethane, PU) 作為一種高性能的材料備受關注。水性PU離聚物是綠色的、環境友好的高分子，但是通常PU的水分散液黏度太低，無法直接3D列印。在本研究中，通過在合成過程中加入纖維素奈米纖絲 (cellulose nanofibrils, CNFs)，成功製備出可直接列印的PU複合物。通過調控PU製備過程中加入的中和劑的量，可以有效改變最終PU/CNF複合分散液的黏度。流變學分析表明複合墨水有著優異的列印性。TEM圖像揭示了，借助物理化學多種鍵接，CNFs穿過多個PU奈米粒子形成串燒的結構，這一結構成功提高了PU/CNF複合分散液的黏度。3D列印後的PU/CNF支架有著優異的結構保真度和穩定性。同時，PU/CNF支架的壓縮模量遠高於通過加入增稠劑 (PEO) 列印的支架。在引入CNFs後，PU的體外降解速率提高了3倍。纖維母細胞在3D列印的支架中保持活性與增殖超過一周。PU/CNF支架將會有著各種各樣的應用，特別是在生物醫用領域。此外，CNF與PU之間的相互作用力提供了一種新型的、獨一無二的方法去調整水性PU分散液的黏度，以至於可以直接3D列印。

3D printing technology has been booming in various fields as a new type of layer-by-layer additive manufacturing technology. Unlike traditional manufacturing techniques, 3D printing has the advantage of customization and does not require expensive molds. Polyurethane (PU) has attracted attention as high performance materials. Waterborne PU ionomers are green, eco-friendly polymers but the viscosity of PU dispersion is generally too low for direct 3D printing. In the study, printable PU composites were successfully prepared by introducing cellulose nanofibrils (CNFs) during the synthesis of PU. The viscosity of the PU/CNF composite dispersion was effectively regulated by the amount of neutralizing agent in preparing anionic PU. Rheological measurements supported the good printability of the composite ink. TEM images revealed that CNFs linked multiple PU nanoparticles to form a ‘skewer’ structure through the physical and chemical interaction force, which successfully increased the viscosity of PU/CNF water dispersion. PU/CNF scaffolds were 3D printed from the composite ink with excellent pattern fidelity and structure stability. Meanwhile, the compression modulus of PU/CNF scaffolds was much higher than that of scaffolds printed with the common viscosity enhancer (PEO). The degradation rate of PU increased three times after the introduction of CNFs. Fibroblasts kept proliferating in the 3D printed PU/CNF scaffolds for more than a week. The printed PU/CNF composites may have various applications particularly in the biomedical field. Moreover, the interaction between CNF and PU may offer a novel and unique way to tune the viscosity of waterborne PU dispersion for direct 3D printing.