Investigation of the morphology and surface properties of crosslinked poly(urethane-ester-siloxane)s

Abstract

Two series of crosslinked poly(urethane-ester-siloxane)s were synthesized from ?,?-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO), 4,4?-methylenediphenyl diisocyanate and Boltorn? hyperbranched polyesters of the second and third pseudo generation, by a two-step polymerization in solution. The effect of the EO-PDMS-EO content and functionality of the applied crosslinking agent on the morphology and surface properties of the prepared poly(urethane-ester-siloxane)s was investigated by FTIR spectroscopy, small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and water absorption measurement. Different techniques (FTIR peak deconvolution, SAXS and AFM) revealed that decrease of the crosslinking agent functionality and EO-PDMS-EO content promotes microphase separation in the synthesized poly(urethane-ester-siloxane)s. SEM analysis and water absorption experiments showed that due to the hydrophobic character of EO-PDMS-EO and its ability to migrate to the surface of poly(urethane-ester-siloxane)s, samples synthesized with higher EO-PDMS-EO content and crosslinking agent of lower functionality have more hydrophobic surface and better waterproof performances. The obtained results indicate that the synthesis of poly(urethane-ester-siloxane)s based on EO-PDMS-EO and Boltorn? hyperbranched polyesters leads to the creation of networks with interesting morphological and surface properties, which can be easily tailored by changing the content of EO-PDMS-EO segment or functionality of hyperbranched polyester.