IN SITU visualization of water adsorption in cellulose nanofiber film with micrometer spatial resolution using micro-FTIR imaging

Abstract

Hygroscopic behavior is an inherent characteristic of nanocellulose film which strongly affects its applications. In order to gain a better understanding of water adsorption, micro-Fourier transform infrared (FTIR) imaging was used to investigate the water adsorption in cellulose nanofiber film with a spatial resolution of 20 um. Four spectral peaks at 2905 cm⁻¹, 1428 cm⁻¹, 1371 cm⁻¹, and 1317 cm⁻¹ attributed to CH and CH₂ groups were used to generate 2D micro-FTIR images of cellulose distribution, and the most intense peak at 3348 cm⁻¹ was employed to generate 2D micro-FTIR image of OH group distribution. On this basis, difference 2D micro-FTIR images of OH group distribution at different relative humidity (RH) levels demonstrated the development of adsorbed water distribution in cellulose nanofiber film during the water adsorption process. The study results confirmed that the micro-FTIR imaging was one promising tool for in situ visualization of water adsorption with micron-scale resolution.

Keywords:

• Cellulose nanofiber film
• relative humidity
• micro-FTIR images
• adsorbed water distribution
• water adsorption

Acknowledgments

The authors were grateful to Qinglin Wu at Louisiana State University AgCenter for skilled preparation of cellulose nanofiber film.

Disclosure Statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was financed by the National Natural Science Foundation of China (Grant No. 31500475 and 31530009), China Postdoctoral Science Foundation (Grant No. 2014M562146 and 2016T90768), Research Foundation of Education Bureau of Hunan Province (Grant No. 15B256) and Hunan Province Science and Technology Project (Grant No. 2015RS4046).