Water desorption from a confined biopolymer.
basic_science · Level V
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- Record sourced from PubMed, PMID 29492505.
- Also identified by DOI 10.1039/c7sm02332d.
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Abstract
We study desorption of water from a confined biopolymer (chitosan thin films) by employing temperature dependent specular X-ray reflectivity and spectroscopic ellipsometry. The water desorption is found to occur via three distinct stages with significantly different desorption rates. The distinct rates of water desorption are attributed to the presence of different kinds of water with disparate mobilities inside the biopolymer film. We identify two characteristic temperatures (T<sub>c1</sub> and T<sub>c2</sub>) at which the water desorption rate changes abruptly. Interestingly, the characteristic temperatures decrease with decreasing the film thickness. The thickness dependence of the characteristic temperature is interpreted in the context of a higher mobility of polymer chains at the free surface for polymers under one-dimensional confinement.