Incorporation of core–shell particles into methacrylate based composites for improvement of the mechanical properties

Abstract

The fracture toughness of polymeric materials and composites can be enhanced by the incorporation of polymer nanoparticles. The combination of a soft core and a hard shell leads to an improvement of the fracture toughness of the polymeric composites. Thereby, the mechanical resistance of the materials is commonly decreased. In our approach, core-shell nanoparticles consisting of an ethylene glycol dimethacrylate (EGDMA) crosslinked poly(butyl acrylate) (PBA) core and a poly(methyl methacrylate) (PMMA) shell were synthesized. The polymer particles were incorporated into triethylene glycol dimethacrylate (TEGDMA)/urethane dimethacrylate (UDMA) based composites in order to tune the mechanical properties. Different core-shell ratios were applied to study the influence on the fracture toughness and E-modulus. An examination of shell-crosslinking with a TEGDMA content of up to 8% was performed to improve particle stability and dispersibility. The particle sizes and morphologies were characterized by dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM) and analytical ultracentrifugation (AUC). Latex particle sizes of 70 to 220 nm were obtained. The mechanical properties (flexural strength, E-modulus and K 1c ) of polymer composites were investigated in three-point bending tests. Core/shell ratios of 50/50 showed a decreasing effect on flexural strength, E-modulus and K 1c .Polymer particles with core/shell ratios of 30/70 led to a significant increase of the mechanical properties with maxima of 1.206 MPa m 1/2 (K 1c ) (increase of 65%), E-modulus of 1.90 GPa (increase of 18%) and flexural strength of 79 MPa (increase of 18%). This study represents the first report of a simultaneous improvement of fracture toughness and E-modulus (at the same time) of additive filled polymer composites. The improvement of mechanical properties makes these materials interesting as tougheners for hard tissue applications like bone cements or dental replacement materials. † Electronic supplementary information (ESI) available. See

Toughening of photo-curable polymer networks: a review

“…Sandmann et al used particles with EGDMA/PBA cores and PMMA shells to improve the mechanical properties of urethane dimethacrylate/TEGDMA based dental composites. 144 Best results were found with a core-shell ratio of 30/70, which showed a fracture toughness of 1.21 MPa m 1/2 (an improvement of 65%), a flexural modulus of 1.90 GPa (an increase of 18%) and a flexural strength of 79 MPa (also an increase of 18%). Success in this case is likely due to good compatibility and thus adhesion of the PMMA shell with the TEGDMA matrix and reduced polymerization shrinkage of the urethane based monomer.…”

Silica-Coated Core–Shell Structured Polystyrene Nanospheres and Their Size-Dependent Mechanical Properties

“…Schubert et al found that the fracture toughness and elastic modulus of polymer composites can be enhanced at the same time. 11 They combined a soft core and a hard shell to improve the fracture toughness of polymeric composites. The improvement of the mechanical properties makes these composite materials valuable for hard tissue applications such as dental replacement materials or bone cements.…”

“…Schubert et al found that the fracture toughness and elastic modulus of polymer composites can be enhanced at the same time . They combined a soft core and a hard shell to improve the fracture toughness of polymeric composites.…”

Controllable supramolecular polymerization through self-sorting of aliphatic and aromatic motifs

“…Consequently, samples can be detected in their nature states, which greatly benefits the characterization of supramolecular systems. 60,61 As shown in Fig. 4a, we observed directly signals of absorbance that illustrate the ultracentrifugation process.…”