Functional bioglass/carbon nanocomposite scaffolds from vat photopolymerization of a novel preceramic polymer-based nanoemulsion

Abstract

Silicone polymers are already known as feedstock for a variety of silicate bioceramics, in the form of scaffolds with complex shapes, obtained by Vat Photopolymerization. Printing is enabled by using silicone blended with photocurable acrylates. The development of a particular silicate composition that functions as a glass or glass-ceramic precursor is possible by the addition of suitable oxide fillers (especially carbonate powders), suspended in the polymer blend. Oxides, from the fillers, easily react with silica left by the thermal transformation of the silicone. The fillers, however, also determine complications in Vat Photopolymerization, due to light scattering; in addition, local oxide concentrations generally impede the obtainment of glassy products. The present paper illustrates a simple solution to these issues, based on the inclusion of a Ca salt in nano-emulsion within a silicone-containing blend. Homogeneous printed samples are later converted into crack-free, fully amorphous ceramic composites, by firing at only 700 °C. The glass matrix, resembling 70S30C (70 % SiO2 and 30 % CaO) bioglass, is achieved according to the quasi-molecular CaO distribution. The secondary phase, promoted by treatment in N2 atmosphere and consisting of pyrolytic carbon, provides a marked photothermal effect.