Preparation of sorbitol‐based polyurethanes and their semiinterpenetrating polymer networks

Abstract

ABSTRACT Sorbitol is a useful agro‐based substance that is inexpensive and commercially available. In the interest of adding value to bio‐based raw materials, we have synthesized polyurethanes from sorbitol and toluene‐2,4‐diisocyanate (TDI) through both conventional heat and microwave processes. Relative to conventional heat, the microwave process achieved the same reaction at a faster rate, thereby saving time and energy. The nature of the resulting polyurethane products depended on the stoichiometry of the reaction. At increasing TDI levels, a viscous liquid, a soft gel, or a hard thermoset could be obtained. The polymers were fully characterized with 13 C‐NMR, Fourier transform infrared, size exclusion chromatography, and thermogravimetric analysis. The polyurethanes obtained near the gel point could be used to make semiinterpenetrating polymer networks (semi‐IPNs) with a second polymer, thereby imparting some of the properties of the second polymer onto the sorbitol‐based polyurethane. For illustration, the sorbitol‐based polyurethane semi‐IPNs were made in combination with poly(vinyl pyrrolidone) and poly(lactic acid). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47602.