Cellulosic Polymer Blends 2: With Aliphatic Polyesters

Abstract

This chapter presents a review of the authors’ studies on blends of cellulosic and chitinous polymers with a typical biodegradable polyester, poly(e-caprolactone) (PCL). A miscibility map is constructed for a series of cellulose ester (CE)/PCL blends as a function of the carbon number (N) in the acyl substituent of CE and the degree of substitution (DS). The map reveals that cellulose butyrate (CB), with N = 4, is miscible with PCL at a comparatively lower DS, owing to a structural similarity advantage for the ester side-group of CB with a repeating unit of PCL. The melt-crystallization behavior of PCL in the miscible blends is also described, and the observed slower kinetics is interpreted in terms of a thermodynamic diluent effect of the CE component. A similar miscibility characterization is made for a comparable series of acylated chitin (Acyl-Ch)/PCL blends. The blend miscibility of the chitinous series is generally lower owing to the concurrence of N-acylation at the C2 position than that for the cellulosic series. The tensile ductility and cytocompatibility are evaluated for selected Acyl-Ch/PCL blends with different degrees of miscibility and crystallinity, by using their thermally molded and alkali-treated films. The adaptability of the chitinous blends as cell-scaffolding materials is attainable by adequately controlling the mixing state of the polymer components.