How to overcome the light penetration issue in photopolymerization? An example for the preparation of high content iron-containing opaque composites and application in 3D printing

Abstract

Research on metal polymer composites (MPCs) has made tremendous progress in last 20 years, gaining a series of lightweight materials. However, the underlying theory of MPCs has not been fully developed and its preparation is hardly done by photopolymerization process, which is hampered by the problem of high filler content and light penetration issue. Herein, we introduce an efficient photothermal synergistic approach to break the limits of the light reaction alone by collecting the heat release by the photopolymerization, for the fabrication of poly(trimethylolpropane triacrylate) containing iron fillers under LED@405 nm irradiation and air. Markedly, the cured composites are characterized by depth of cure (DoC) increased at least 10 times (19 mm) vs. a pure photochemical approach (DoC < 2 mm alone). Meanwhile, we investigated the difference in properties between various iron content from 0% to 50% by dynamic mechanical analysis. Remarkably, an obvious increase of elastic modulus (G′) at 25 °C was observed and the highest value occurred at 30% Fe wt%, indicating the enhanced mechanical property. Lastly, the 3D printing was conducted successfully using the iron filler-based composites with good spatial resolution. We consider this method allows for the manufacture of Pan-Scaled polymerization products from thin to thick and opaque samples that remain inaccessible in classical photopolymerization approaches.