利用机械化学法“一步”制备月桂酸纤维素酯

Direct One-step Synthesis of Cellulose Laurate Ester via Mechanochemical Method

以微晶纤维素(MCC)、三氟乙酸酐(TFAA)和长链月桂酸(LA)为原料,通过机械球磨一步法制备具有高取代度(DS>2.5)的月桂酸纤维素酯(LCE),并探讨了机械化学条件对产物取代度、熔融行为和热稳定性的影响.结果表明,随着球磨转速和球磨时间的增加,产物LCE的取代度提高,熔融温度下降,当DS≥2.81时,能得到完全熔融的LCE.在投料比为1:6:3,且以400 r/min球磨处理4 h时,能制备流动温度(T_(f))为115℃且分解温度高达324℃的纤维素月桂酸酯.此外,初步探讨了在体系中引入PVA对过量的TFAA以及副产物三氟乙酸进行收酸的效果,分析数据表明PVA成功固定了三氟乙酸.本策略在简化制备过程、减少单体用量、缩短反应时间和环境友好等方面相较于传统均相手段具有显著的优势,有望应用于工业上大规模地制备热塑性纤维素衍生物.

This study presents a simple method for obtaining LCE with high degree of substitution(DS>2.5)by directly utilizing microcrystalline cellulose(MCC),trifluoracetic anhydride(TFAA),and long chain lauric acid(LA).The impact of ball milling speed,grinding time,and feeding ratio on substitution,melting behavior,and thermal stability is thoroughly investigated.The results show that with increasing ball milling speed and time,LCE substitution increased and the melting temperature decreased.When the DS is larger than 2.81,LCE can be completely melted.Optimal conditions involve a feed ratio of 1:6:3,and ball milling at 400 r/min for 4 h yields cellulose laurel ester with a flow temperature(T_(f))of 115℃ and a decomposition temperature of 324℃.In addition,the introduction of PVA into the system is explored to mitigate excessive TFAA and the side product trifluoroacetic acid.The results show that PVA not only fixed trifluoroacetic acid successfully but also had little effect on the melting and processing properties of the product.This strategy has significant advantages over conventional homogeneous methods,such as streamlining the preparation process,reducing monomer quantities,shortening reaction time,and promoting environmental friendliness.Its potential application in large-scale industrial production of thermoplastic cellulose derivatives is promising.