Hishikawa Yukako, Togawa Eiji, Kondo Tetsuo
Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba 305-8687, Ibaraki, Japan.
Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan.
ACS Omega. 2017 Apr 17;2(4):1469-1476. doi: 10.1021/acsomega.6b00364. eCollection 2017 Apr 30.
Cellulose nanofibers (CNFs), which are directly isolated as a native form, have drawn considerable attention as eco-friendly and distinctive material to be partly substituted for fossil products. In addition to the increasing attention to the native CNFs, conventional regenerated cellulose having cellulose II crystals also attracts more attention because of its cost-effective method of production in a moderately easy and repeatable fashion. Inter- and intramolecular hydrogen bonds are, in particular, thought to contribute greatly to the physical properties of cellulosic commercial products. More than half century ago, Marchessault et al. attempted to directly assign the hydroxyl (OH) group vibrations related to hydrogen bonding in infrared (IR) spectra. The assignment, however, has not been significantly updated. One reason for the delayed assignments is the difficulty in preparing pure cellulose II. Here, we show successful IR assignments of the interacted OH groups in cellulose II by using the nematic ordered cellulose to prepare a highly oriented regenerated film. The film had anisotropic crystalline domains, which provided a clearly resolved component in the IR spectra. The OH bands were well assigned, and this IR assignment becomes an effective tool to understand the structure-property relationship for engineering advanced regenerated cellulose materials.
直接以天然形式分离得到的纤维素纳米纤维（CNFs），作为一种可部分替代化石产品的环保且独特的材料，已引起了广泛关注。除了对天然CNFs的关注度不断提高外，具有纤维素II晶体的传统再生纤维素也因其以适度简便且可重复的方式进行生产的成本效益方法而备受关注。特别是，分子间和分子内氢键被认为对纤维素商业产品的物理性能有很大贡献。半个多世纪前，马尔切索尔特等人试图在红外（IR）光谱中直接确定与氢键相关的羟基（OH）基团振动。然而，这一归属并未得到显著更新。归属延迟的一个原因是制备纯纤维素II存在困难。在此，我们通过使用向列相有序纤维素制备高度取向的再生膜，成功地对纤维素II中相互作用的OH基团进行了红外归属。该膜具有各向异性的结晶域，这在红外光谱中提供了一个清晰分辨的成分。OH谱带得到了很好的归属，并且这种红外归属成为理解先进再生纤维素材料结构 - 性能关系的有效工具。
