Near-infrared light responsive shape memory polymers from bio-based benzoxazine/epoxy copolymers produced without using photothermal filler

Abstract

Shape memory polymers (SMPs) that can be actuated by a near-infrared (NIR) light are of high interest due to their potential applications in biomedical field. In this work, SMPs that could be actuated by an NIR light without using any NIR photothermal filler was introduced for the first time. Benzoxazine/epoxy (V-fa/ECO) copolymers with a shape memory property were synthesized from bio-based raw materials, which were vanillin, furfurylamine, paraformaldehyde, and epoxidized castor oil. The glass transition temperature of the copolymers could be tuned from 144 to 14 °C, by increasing the ECO content from 40 to 60% by weight. The V-fa/ECO copolymers were found to exhibit a shape memory property that could be remotely actuated by an NIR laser with a wavelength of 808 nm. A high recovery ratio of 100% within a 30 s of NIR irradiation was achieved when the percent weight of ECO in the copolymers was at least 50. We found that the shape memory property of V-fa/ECO copolymers was due to their photothermal effect in the NIR region that could induce the shape recovery process. The temperature of V-fa/ECO copolymers rose from room temperature to 100 °C within a 30 s of NIR irradiation (laser power density of 2.5 W/cm2). It was proposed that the π-conjugation in benzene rings of copolymers might play role on their NIR photothermal effect, due to the π-π interactions between polymer chains. The findings of this study suggested a new way to produce NIR light responsive SMPs without using any NIR photothemal filler.