Design of Polysaccharide-based New Materials Exhibiting Magnetic and Electromagnetic Functions.by Use of Ion-associated Chelation and Gelation Characteristics of Carbohydrate Polymers

利用糖类聚合物的离子缔合和凝胶特性，设计了具有磁性和电磁功能的多糖基新材料。研究结果如下：1.海藻酸盐/聚乙烯醇/氧化铁磁性复合材料：采用原位合成法成功制备了含氧化铁的海藻酸盐凝胶。将海藻酸盐在铁盐水溶液中进行交联，得到的凝胶浸泡在不同的碱性溶液中，得到了离子交换凝胶。凝胶样品用氧化剂处理，然后在冷冻状态下干燥。SQUID磁学测量表明，干凝胶在室温下表现出超顺磁性或铁磁性，这取决于碱处理中金属阳离子的种类。通过对上述方法的改进，还制备了含离子氧化物的IPN型海藻酸盐/聚乙烯醇复合材料。2.卡拉胶-氧化铁磁性复合材料：通过原位合成氧化铁制备卡拉胶基磁性复合材料，制备了卡拉胶基磁性复合材料。进行了电子显微镜观察和磁测量。结果表明，在298K时，复合材料几乎表现出超顺磁性，磁铁矿和/或磁铁矿颗粒以小于几十纳米的尺度分散在卡拉胶基质的内部和纤维状实体的内表面。3.纤维素衍生物/无机盐离子介观体系：使含盐离子的羟丙基纤维素水溶液和凝胶的介观结构特征更加清晰。探索了一种电光功能来从外部控制介晶溶液和网络的反射变色和浑浊度。

Polysaccharide-based new materials ehibiting magnetic and electromagnetic functions were designed by, utilizing ion-associated chelation and gelation characteristics of carbohydrate polymers. The following results are worth noting.1.Magnetic Composites of Alginate/Poly vinyl alcohol) with Iron Oxide:Alginate-based gels containing iron oxides were prepared successfully by an in situ synthesis technique. Alginate was crosslinked in iron salt aqueous solution, and' the resulting gels were immersed into different alkaline solutions, whereupon i.on-exchanged gels were obtained. The gel samples were treated with an oxidizing agent, then dried in frozen state. SQUID magnetometry revealed that the dried gels showed superparamagnetism or ferromagnetism at room temperature, depending on the sort of metallic cation in the alkali treatment. IPN-type alginate/poly(vinyl alcohol) composites containing ion oxides were also prepared by modifying the above method. 'The, dynamic viscoelastic property of the composites was examined in gelatinous state, in addition to SQUID measurements.2.Magnetic Composites of Carrageenan -Iron Oxide:Carrageenan-based magnetic composites were prepared via in situ synthesis, of iron oxides in a similar way stated above. Electron microscopic observations and magnetometry measurements were conducted. It was found that almost alt the composites exhibited superparamagnetic character at 298K, and that magnetite and/or maghemite particles were dispersed in a scale less than several tens of nanometers in the interior as well as on the inner surface of fibrillar entities constituting the carrageenan matrix.3.Mesoscopic Systems of Cellulose Derivative/Inorganic Salt Ions:Mesoscopic structural characteristics of aqueous (hydroxypropyl)cellulose solutions and gels containing salt ions were made clearer. An electrooptical function was explored to control externally the reflective coloration and turbidity of the mesomorphic solutions and networks.