ABSTRACT
Controlling the self-assembled nanoscale ionic aggregates in single-ion conducting polymers is a crucial step toward exceptional transport properties. We report a series of precisely segmented polyethylene-like materials containing sulfonate groups (PES23) with Li+, Na+, Cs+, or NBu4+ counterions synthesized from step-growth polymerization. At room temperature, all polymers are semicrystalline with well-defined nanoscale ionic layers separated by 35-38 Å, depending on the cation. In situ X-ray scattering measurements reveal that the layered ionic aggregates in PES23Li, PES23Na, and PES23Cs transform, upon melting the PE blocks, into the Ia3d gyroid morphology. The gyroidal ionic aggregates in PES23Li and PES23Na further evolve into hexagonal symmetry as the temperature increases. These order-to-order transitions in ionic aggregate morphologies were also confirmed by oscillatory shear rheology. The ion transport behavior of these PES23 polymers is strongly dependent on the ionic aggregate morphologies. Specifically, the 3D interconnected gyroid morphology of PES23Li exhibits higher ionic conductivity than the isotropic layered or hexagonal morphologies. This innovative and versatile molecular design of single-ion conducting polymers leads to unprecedented percolated gyroidal ionic aggregate morphologies that provide a continuous pathway for improved ion transport.
ABSTRACT
PURPOSE: A biomechanical study was performed to test the hypothesis that a new anatomically preformed, thinner, soft-tissue protecting plate system for distal humeral fractures (Tifix®-hybridplate [HP]) would show comparable results in the quasi-static and dynamic testings compared to two conventional implants: The 3.5-mm reconstruction plate (RP) providing primary stability with normal bone mineral density (BMD), and a multidirectional locking plate (Tifix(®)-plate [P]) which can be used with poor bone quality. METHODS: The Tifix(®)-HP was developed by the working group. The biomechanical testing was performed on a C2-fracture-model in 24 synthetic humeri. Three groups, each with eight bone-implant-constructs, were analysed in quasi-static and dynamic tests. RESULTS: The quasi-static measurements showed that under extension loading both locking plates (Tifix(®)-P, Tifix(®)-HP) were significantly stiffer than the reconstruction plate, and that the Tifix(®)-HP had a significantly lower stiffness than the two other implants under flexion loading. In the dynamic tests the Tifix(®)-P allowed significantly less fracture motion compared to the Tifix(®)-HP and the reconstruction plate. In an osteopaenic bone model locking plates failed only under much higher dynamic force than the reconstruction plate. The reconstruction plate and the Tifix(®)-P always failed through screw loosening, whereas the newly developed Tifix(®)-HP showed screw loosening in only one third of cases. CONCLUSION: The hypothesis that the newly designed plate system showed comparable results in the quasi-static and dynamic tests compared to the conventional implants with a significantly lower implant volume and thickness was confirmed.
