3D Printing of Supramolecular Polymers: Impact of Nanoparticles and Phase Separation on Printability.

Abstract

3D printing of linear and three-arm star supramolecular polymers with attached hydrogen bonds and their nanocomposites is reported. The concept is based on hydrogen-bonded supramolecular polymers, known to form nano-sized micellar clusters. Printability is based on reversible thermal- and shear-induced dissociation of a supramolecular polymer network, which generates stable and self-supported structures after printing, as checked via melt-rheology and X-ray scattering. The linear and three-arm star poly(isobutylene)s PIB-B2 (Mn = 8500 g mol -1 ), PIB-B3 (Mn = 16 000 g mol -1 ), and linear poly(ethylene glycol)s PEG-B2 (Mn = 900 g mol-1 , 8500 g mol -1 ) are prepared and then probed by melt-rheology to adjust the viscosity to address the proper printing window. The supramolecular PIB polymers show a rubber-like behavior and are able to form self-supported 3D printed objects at room temperature and below, reaching polymer strand diameters down to 200-300 µm. Nanocomposites of PIB-B2 with silica nanoparticles (12 nm, 5-15 wt%) are generated, in turn leading to an improvement of their shape persistence. A blend of the linear polymer PIB-B2 and the three-arm star polymer PIB-B3 (ratio ≈ 3/1 mol) reaches an even higher structural stability, able to build free-standing structures.