共溶剂存在下N-烯丙基吡啶氯盐离子液体对纤维素的溶解性能研究

采用一步法合成N-烯丙基吡啶氯盐离子液体(APy]Cl),考察其对纤维素的溶解性能.结果发现,在120℃下对棉浆粕(聚合度(DP)=556)的溶解度可高达19.71%,但再生后聚合度为223,热降解严重.通过添加不同种类共溶剂的方法克服此缺点.结果表明,有机溶液(DMSO,DMAc,DMF或吡啶)作为APy]Cl的共溶剂时,APy]Cl/DMAc复合溶剂对棉浆粕的溶解效果最佳,100℃下溶解度为15.03%,再生后聚合度为403.此外降低了溶剂成本.但70℃下,溶解度仅为1.36%,溶解能力较弱.继续探讨了AMIM]Cl作为APy]Cl的共溶剂时对纤维素的溶解性能,结果表明,70℃下,APy]Cl/AMIM]Cl复合溶剂对棉浆粕的溶解度为8.78%,再生后聚合度为516.可知添加上述2种共溶剂均使APy]Cl在低于自身熔点下形成液体并能够溶解一定量纤维素,拓宽了溶解温度区间及应用平台.对FTIR,XRD和TGA谱图分析,结果表明上述为纤维素的直接溶剂,可将其晶型由Ⅰ型转变成Ⅱ型,再生后热稳定性稍有降低.通过照片和SEM表明再生膜无色透明,结构致密.

STUDY ON THE DISSOLUTION OF CELLULOSE IN N-ALLYLPYRIDINIUM CHLORIDE IONIC LIQUID AND CO-SOLVENT COMPOSITES

N-allylpyridinium chloride ionic liquid(Cl) was synthesized by one-step process and its property of dissolving cellulose was investigated.The results showed that the solubility of cotton linter pulp cellulose(degree of polymerization(DP)=556) was 19.71% at 120℃,and the thermostability of regenerated cellulose(DP=223) seriously decreased.The performance of regenerated cellulose could be enhanced by adding cosolvents into Cl.Compared with other cosolvent(DMSO,DMF or pyridine),the Cl/DMAc composite solvent exhibited a better dissolution to cotton linter pulp cellulose.The solubility was 15.03% and the DP of regenerated cellulose was 403 at 100℃ with lower cost.But the solubility of Cl/DMAc was only 1.36% at 70℃.So,the Cl/1-N-ally1-3-methylimidazolium chloride ionic liquid(Cl) solvent was discussed afterwards.The results showed that the solubility of cotton linter pulp was 8.78% and the DP of regenerated cellulose was 516 in Cl/Cl composite solvent at 70℃.Besides,Cl/DMAc and Cl/Cl were liquid respectively below the melting point of Cl and they were the potential cellulose solvent.The FTIR,XRD and TGA spectrograms showed that these solvents were non-derivatizing solvents for cellulose,the cellulose was changed from cellulose Ⅰ to cellulose Ⅱ during dissolution and regeneration and the thermal stability of the regenerated cellulose slightly decreased.The photographs and SEM image indicated that the regenerated cellulose membrane was homogeneous and dense.