PDF(Pubmed)
Abstract：
Because of the pronounced degradation of the environment, there has been an escalated demand for the fabrication of eco-friendly and highly efficient products derived from renewable sources. Cellulose aerogels have attracted significant interest attributable to their structural characteristics coupled with biodegradability and biocompatibility. The features of the molecular structure of cellulose allow for the use of various methods in the production of gels. For instance, the presence of hydroxyl groups on the cellulose surface allows for chemical crosslinking via etherification reactions. On the other hand, cellulose gel can be procured by modulating the solvent power of the solvent. In this study, we investigate the impact of the gelation methodology on the structural attributes of aerogels. We present methodologies for aerogel synthesis employing three distinct gelation techniques: chemical crosslinking, cryotropic gelation, and CO2-induced gelation. The outcomes encompass data derived from helium pycnometry, Fourier-transform infrared spectroscopy, nitrogen porosimetry, and scanning electron microscopy. The resultant specimens exhibited a mesoporous fibrous structure. It was discerned that specimens generated through cryotropic gelation and CO2-induced gelation manifested higher porosity (93-95%) and specific surface areas (199-413 m2/g) in contrast to those produced via chemical crosslinking (porosity 72-95% and specific surface area 25-133 m2/g). Hence, this research underscores the feasibility of producing cellulose-based aerogels with enhanced characteristics, circumventing the necessity of employing toxic cross-linking agents. The process of gel formation through chemical crosslinking enables the creation of gels with enhanced mechanical properties and a more resilient structure. Two alternative methodologies prove particularly advantageous in applications necessitating biocompatibility and high porosity. Notably, CO2-induced gelation has not been hitherto addressed in the literature as a means to produce cellulose gels. The distinctive feature of this approach resides in the ability to combine the stages of obtaining an aerogel in one apparatus.
摘要：
由于环境的显著恶化，对制造来自可再生资源的环保高效产品的需求不断增加。纤维素气凝胶由于其结构特征与生物降解性和生物相容性而引起了人们的极大兴趣。纤维素的分子结构的特征允许在凝胶的生产中使用各种方法。例如,纤维素表面上羟基的存在允许经由醚化反应的化学交联。另一方面,纤维素凝胶可以通过调节溶剂的溶剂能力来获得。在这项研究中,我们研究了凝胶化方法对气凝胶结构属性的影响。我们提出了采用三种不同凝胶化技术的气凝胶合成方法：化学交联，低温凝胶化,和CO2诱导的凝胶化。结果包括来自氦比重计的数据，傅里叶变换红外光谱,氮气孔隙率法,和扫描电子显微镜。所得样品表现出中孔纤维结构。可以看出,与通过化学交联产生的样品(孔隙率72-95%和比表面积25-133m2/g)相比,通过低温凝胶化和CO2诱导的凝胶化产生的样品表现出更高的孔隙率(93-95%)和比表面积(199-413m2/g)。因此，这项研究强调了生产具有增强特性的纤维素基气凝胶的可行性，规避使用有毒交联剂的必要性。通过化学交联形成凝胶的过程能够产生具有增强的机械性能和更有弹性的结构的凝胶。两种替代方法证明在需要生物相容性和高孔隙率的应用中特别有利。值得注意的是,迄今为止,在文献中还没有提出CO2诱导的凝胶化作为生产纤维素凝胶的手段。该方法的显著特征在于能够在一个装置中组合获得气凝胶的阶段。
