Fabrication of retro-reflective polyurethane via covalently embedding with amino-functionalized glass microspheres

Amino-functionalized glass microspheres (NH2-GM) grafted with 3-aminopropyltriethoxysilane (APTS) were synthesized and well characterized by X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and scanning electron microscope (SEM). Then the NH2-GM was covalently incorporated into polyurethane (PU) matrix through urea linkages to fabricate a composite with retro-reflective effect, and the influence of NH2-GM content on the retro-reflective performance, glass transition temperature, morphology structure and mechanical properties of the resultant glass microspheres based retro-reflective polyurethane (GMPU) were investigated. Results demonstrate that GMPU maintains initial retro-reflective properties and reflects bright light under vertical angle incidence in darkness. Moreover, compared with PU directly blending with GMs (GM/PU), GMPU shows clear improved compatibility and interfacial interactions between PU and NH2-GMs, as evidenced by the higher glass transition temperature and enhanced mechanical properties of GMPU hybrids.