Spacer length controlled highly thermo reversible polyurethane–urea based on polystyrene: synthesis and crystallization studies

Poly(urethane–urea) (PUU) is prepared using dihydroxy functionalized polystyrene having M_w 2000 g/mol, 1,6 hexamethylene diisocyanate and three different diamines (1,2‐ethylenediamine, 1,4‐butanediamine and 1,6‐hexamethylene diamine) by melt polymerization method. The synthesized copolymer is characterized by viscosity measurements, Fourier transform infrared (FT‐IR) spectroscopy, wide angle 2D‐X‐ray scattering (WAXS) and differential scanning colorimetry (DSC). The inherent viscosity of the polymers is found to be in the range of 0.4–0.5 dl/g, suggesting that the polymers are of high molecular weight. FT‐IR results conclude that the urea groups form both monodendate and bidendate assemblies. Temperature‐dependent FT‐IR and WAXS data confirm that the crystallinity of the copolymer is highly reversible and depends on the spacer length. DSC data also confirm that the crystallization pattern depends on the spacer length. The swelling behavior in water and the solubility of the polymer in chloroform are depending on the type of chain extender used in the PUU synthesis. Copyright © 2014 John Wiley & Sons, Ltd.