甲基化修饰对纤维素基磁性材料结构基元的磁性调控

目前市面上电磁功能纺织品的磁性大都来自于染色、涂覆、整理等过程中磁性微粒的额外添加,但上述方法赋予纺织品一定程度磁性的同时持久性较差。研究了纤维素基磁性材料结构基元纤维二糖分子的原始态和甲基化修饰态,意图得到本身固有磁性的纤维素纤维。具体地说,是将纤维二糖分子2号位碳原子上仲羟基的氢原子替换为甲基基团,得到甲基化修饰的纤维二糖分子。DFT表明,甲基化修饰使纤维二糖分子的能量基态由三重态转变为开壳层破损态单重态;同时,磁性耦合常数由原始态的1.23 cm^-1变为甲基化修饰态的-0.65 cm^-1,正值变为负值也意味着体系从铁磁性到反铁磁性的磁性转变。经过甲基化修饰,该体系可作为构建具有长久磁性的新型磁性纤维材料的结构基元。

Magnetic Control of the Building Blocks of Cellulose-Based Magnetic Materials through Methyl Modification

Currently, magnetic properties of magnetic functional textiles almost all originate from the addition of stationary magnetic particles during the finishing process of printing and dyeing, such as coating, dyeing and pasting. Although these methods can give textiles certain magnetism, but the same time its durability are poor. This work studied the parent and methylblocks of cellulose-based magnetic materials. The methyl-modified cellobiose is designed by replacing the hydrogen atom of its 2-point secondary hydroxyl group with one methyl group. DFT and CASSCF calculations prove that the methyl modification makes the ground state of cellobiose changing from triplet to open-shell BS singlet state. And the values for the magnetic exchange coupling constant from positive 1.23 cm~(-1) to negative-0.65 cm~(-1) shows an magnetic conversion from ferromagnetic to antiferromagnetic. Through methyl modification, a promising strategy of designing new cellobioseorganic magnetic switches has been provided.