High-fracture-toughness acrylic-polyurethane-based graft-interpenetrating polymer networks for transparent applications

Transparent materials with robust mechanical properties are essential for numerous applications and require careful manipulation of polymer chemistry. Here, polyurethane (PU) and acrylic-based copolymers out of styrene were utilized to synthesize transparent PU-acrylic graft-interpenetrating polymer networks (graft-IPNs) for the first time. In these materials, PU imparts greater flexibility, while the acrylic copolymer increases rigidity and glass transition temperature of the graft-IPNs. Kinetics of the graft-IPN synthesis was monitored using Fourier transform infrared spectroscopy and H-1 NMR spectroscopy through the conversion of the isocyanate group. System compatibility, degree of phase separation and material transparency were evaluated using transmission electron microscopy and UV-visible spectroscopy. Overall, higher compatibility is observed at a higher percentage of styrene in the acrylate copolymer. The thermomechanical properties of the IPNs were quantified using dynamic mechanical analysis to assess the effect of the acrylic copolymer content on fracture toughness of the resulting graft-IPNs. The high fracture toughness of the graft-IPNs, coupled with excellent transparency, demonstrates the potential of these systems for high-performance applications. (c) 2020 Society of Industrial Chemistry