Preparation of Composite Films of Methacryloyl-modified Lignocresol and Polylactic Acid

Twenty-two superbase-derived ionic liquids (SILs) (16 novel) including 16 1,8-diazabicyclo[5.4.0]undec-7-enium carboxylate (DBU-SILs) and 6 1,5-diazabicyclo[4.3.0]non-5-enium carboxylate (DBN-SILs) were facilely synthesized by coupling superbase cations with different carboxylic anions for cellulose dissolution. Systematic investigations revealed that the combination of the electron-donating groups, small steric hindrance groups, and short-chain groups in carboxylate anions with a larger ring in superbase cations facilitated cellulose dissolution. The regenerated cellulose films produced from seven SILs ([DBUH]-[CH3CH2OCH2COO], [DBUH] [CH3OCH2COO], [DBUH] [CH2=CHCOO], [DBUH] [CH3COO], [DBUH] [CH3CH2COO], [DBNH] [CH3CH2OCH2COO], and [DBNH] [CH3OCH2COO]) with excellent cellulose solubility exhibited similar chemical structures, a high degree of polymerization, sufficient thermostability, smooth morphology, and high mechanical strength.

为实现纤维素溶解，本研究通过将强碱阳离子与不同羧酸阴离子偶联，简便合成了22种强碱衍生离子液体（superbase-derived ionic liquids, SILs），其中16种为新型产物，包含16种1,8-二氮杂双环[5.4.0]十一碳-7-烯羧酸根离子液体（DBU-SILs）与6种1,5-二氮杂双环[4.3.0]壬-5-烯羧酸根离子液体（DBN-SILs）。系统研究表明，羧酸阴离子中的给电子基团、小位阻基团与短链基团，搭配具有大环结构的强碱阳离子，可有效促进纤维素的溶解。以7种对纤维素具备优异溶解性能的SILs（[DBUH]-[CH3CH2OCH2COO]、[DBUH][CH3OCH2COO]、[DBUH][CH2=CHCOO]、[DBUH][CH3COO]、[DBUH][CH3CH2COO]、[DBNH][CH3CH2OCH2COO]及[DBNH][CH3OCH2COO]）制备得到的再生纤维素膜，均具有相似的化学结构、较高的聚合度、良好的热稳定性、平整的表面形貌以及优异的力学强度。