Quantitative Determination of Surface Functional Groups of Cellulose Nanofibers Using Toluidine Blue O Adsorption Method​

User Benefits

- Simple quantitative determination of the surface functional groups of cellulose nanofibers (CNF) is possible with a small sample amount on the order of a few mg per measurement. - Quantitation results with high repeatability and low dependence on individual skill can be obtained. - Due to the extremely short time of one measurement with a UV-Vis spectrophotometer, it is possible to conduct quantitative analyses of 50 specimens in about 2.5 hours.

Introduction

Cellulose is one of the polysaccharides which are the main components of plant cell walls. Among the various types of cellulose, those with a fiber diameter of 4 to 100 nm, length of several μm, and aspect ratio of 100 or more are called cellulose nanofibers (CNF), and have attracted attention as a leading-edge biomass material. In addition to the light weight and high strength of CNF, they also have other excellent functions, including a high gas barrier property, adsorption and transparency, and as a plant-derived material, the environmental impacts of production and disposal are small. In the future, use in automotive components, electronic materials, packaging materials and other applications are expected. The surface of nanocellulose materials can be modified with surface functional groups such as the sulfate groups and carboxy groups to add various functions. In water, the ionic parts of these surface functional groups function as charged groups, improving water dispersibility. Conventionally, the conductometric titration method had been used in quantitative analysis of these surface charged groups. Although this is a general-purpose technique, it has a number of problems, including 1 a large amount (several hundred mg) of sample material is required, 2 the measurement time is long, 3 visual confirmation is necessary, and 4 the results differ depending on the analyst. Therefore, a simple method which does not depend on the skill of the individual analyst has been needed to solve these problems. This article introduces an example of a quantitative analysis of surface functional groups by the toluidine blue O (TBO) adsorption method using a Shimadzu ultraviolet-visible light (UV-Vis) spectrophotometer. This experiment was carried out with the cooperation of Prof. Jun Araki of Shinshu University.

September 26, 2023 GMT