Xu Xiaoming, Guo Guangqing, Fan Yuwei
Department of Comprehensive Dentistry and Biomaterials, Louisiana State University Health Science Center, School of Dentistry, Box 137, 1100 Florida Avenue, New Orleans, LA 70119, USA.
J Nanosci Nanotechnol. 2010 Sep;10(9):5672-9. doi: 10.1166/jnn.2010.2441.
The objective of this study was to prepare dense zirconia-yttria (ZY), zirconia-silica (ZS) and zirconia-yttria-silica (ZYS) nanofibers as reinforcing elements for dental composites. Zirconium (IV) propoxide, yttrium nitrate hexahydrate, and tetraethyl orthosilicate (TEOS) were used as precursors for the preparation of zirconia, yttria, and silica sols. A small amount (1-1.5 wt%) of polyethylene oxide (PEO) was used as a carry polymer. The sols were preheated at 70 degrees C before electrospinning and their viscosity was measured with a viscometer at different heating time. The gel point was determined by viscosity-time (eta-t) curve. The ZY, ZS and ZYS gel nanofibers were prepared using a special reactive electrospinning device under the conditions near the gel point. The as-prepared gel nanofibers had diameters between 200 and 400 nm. Dense (nonporous) ceramic nanofibers of zirconia-yttria (96/4), zirconia-silica (80/20) and zirconia-yttria-silica (76.8/3.2/20) with diameter of 100-300 nm were obtained by subsequent calcinations at different temperatures. The gel and ceramic nanofibers obtained were characterized by scanning electron microscope (SEM), high-resolution field-emission scanning electron microscope (FE-SEM), thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), Fourier transform infrared spectrometer (FT-IR), and X-ray diffraction (XRD). SEM micrograph revealed that ceramic ZY nanofibers had grained structure, while ceramic ZS and ZYS nanofibers had smooth surfaces, both showing no visible porosity under FE-SEM. Complete removal of the polymer PEO was confirmed by TGA/DSC and FT-IR. The formation of tetragonal phase of zirconia and amorphous silica was proved by XRD. In conclusion, dense zirconia-based ceramic nanofibers can be fabricated using the new reactive sol-gel electrospinning technology with minimum organic polymer additives.
本研究的目的是制备致密的氧化锆 - 氧化钇（ZY）、氧化锆 - 二氧化硅（ZS）和氧化锆 - 氧化钇 - 二氧化硅（ZYS）纳米纤维，作为牙科复合材料的增强元素。丙醇锆（IV）、六水合硝酸钇和正硅酸四乙酯（TEOS）用作制备氧化锆、氧化钇和二氧化硅溶胶的前驱体。少量（1 - 1.5 wt%）的聚环氧乙烷（PEO）用作载体聚合物。溶胶在静电纺丝前于70℃预热，并用粘度计在不同加热时间测量其粘度。通过粘度 - 时间（η - t）曲线确定凝胶点。ZY、ZS和ZYS凝胶纳米纤维在接近凝胶点的条件下使用特殊的反应性静电纺丝装置制备。所制备的凝胶纳米纤维直径在200至400nm之间。通过在不同温度下的后续煅烧，获得了直径为100 - 300nm的致密（无孔）氧化锆 - 氧化钇（96/4）、氧化锆 - 二氧化硅（80/20）和氧化锆 - 氧化钇 - 二氧化硅（76.8/3.2/20）陶瓷纳米纤维。通过扫描电子显微镜（SEM）、高分辨率场发射扫描电子显微镜（FE - SEM）、热重分析仪（TGA）、差示扫描量热仪（DSC）、傅里叶变换红外光谱仪（FT - IR）和X射线衍射（XRD）对所得凝胶和陶瓷纳米纤维进行表征。SEM显微照片显示，陶瓷ZY纳米纤维具有粒状结构，而陶瓷ZS和ZYS纳米纤维表面光滑，在FE - SEM下均未显示可见孔隙。TGA/DSC和FT - IR证实聚合物PEO被完全去除。XRD证明了氧化锆四方相和无定形二氧化硅的形成。总之，使用新型反应性溶胶 - 凝胶静电纺丝技术，添加最少的有机聚合物添加剂，可制备致密的氧化锆基陶瓷纳米纤维。
