Swensson Beatrice, Larsson Anette, Hasani Merima
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
Wallenberg Wood Science Center, The Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
Polymers (Basel). 2020 Jun 8;12(6):1310. doi: 10.3390/polym12061310.
To further understand cellulose-solvent interactions in aqueous hydroxide solutions, cellulose behavior in aqueous solutions of NaOH combined with tetramethylammonium hydroxide (TMAH) or benzyltrimethylammonium hydroxide (Triton B), as well as urea, was investigated. The rheological properties of the solutions were assessed through flow sweeps at different temperatures, and the intermolecular interactions were probed using solvatochromic dyes. The results showed that NaOH combined with TMAH had synergistic effects on cellulose dissolution and was a better solvent for cellulose than the combination of NaOH with Triton B, in spite of the superior dissolution ability of Triton B alone. This somewhat unexpected finding shows that the base pair needs to be selected with care. Interestingly, addition of urea had no significant effect on the solvatochromic parameters or dissolution capacity of solutions of Triton B but rendered improved stability of solutions containing NaOH and/or TMAH. It seems that both urea and Triton B weaken the hydrophobic assembly effect of these solutions, but urea is excluded from interacting with cellulose in the presence of Triton B. This study provides further insight into dissolution of cellulose and the possibility of utilizing combinations of hydroxide bases to achieve improved solution properties.
为了进一步了解纤维素在氢氧化水溶液中的溶剂相互作用，研究了纤维素在氢氧化钠与四甲基氢氧化铵（TMAH）或苄基三甲基氢氧化铵（Triton B）以及尿素的水溶液中的行为。通过在不同温度下进行流动扫描来评估溶液的流变性质，并使用溶剂化显色染料探测分子间相互作用。结果表明，尽管Triton B单独具有优异的溶解能力，但氢氧化钠与TMAH组合对纤维素溶解具有协同作用，并且比氢氧化钠与Triton B的组合是更好的纤维素溶剂。这一有些出乎意料的发现表明碱基对的选择需要谨慎。有趣的是，添加尿素对Triton B溶液的溶剂化显色参数或溶解能力没有显著影响，但提高了含有氢氧化钠和/或TMAH的溶液的稳定性。似乎尿素和Triton B都减弱了这些溶液的疏水聚集效应，但在Triton B存在下尿素被排除与纤维素相互作用。这项研究进一步深入了解了纤维素的溶解以及利用氢氧化碱基组合来实现改善溶液性质的可能性。
