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We herein report the fabrication of a Velcro-mimicking surface based on polymer brushes. Using poly(ε-caprolactone) (PCL) as the model polymer, polymer loop brushes (PLBs) and singly tethered polymer brushes (STPBs) with nearly identical tethering point density and brush heights were synthesized using a polymer single crystal (PSC)-assisted grafting-to method. Atomic force microscopy-based single molecular force spectroscopy (AFM-SMFS) and macroscale lap-shear experiments both demonstrated that the PLBs led to strong adhesion that is up to ∼10 times greater than the STPBs, which is attributed to the enriched chain entanglement between the probing polymer and the brushes. We envisage that our results will pave the way towards a new materials design for strong adhesives and nanocomposites. 

Nanocomposite polymer electrolytes (CPEs) are promising materials for all-solid-state lithium metal batteries (LMBs) due to their enhanced ionic conductivities and stability to the lithium anode. MXenes are a new two-dimensional, 2D, family of early transition metal carbides and nitrides, which have a high aspect ratio and a hydrophilic surface. Herein, using a green, facile aqueous solution blending method, we uniformly dispersed small amounts of Ti 3 C 2 T x into a poly(ethylene oxide)/LiTFSI complex (PEO 20 -LiTFSI) to fabricate MXene-based CPEs (MCPEs). The addition of the 2D flakes to PEO simultaneously retards PEO crystallization and enhances its segmental motion. Compared to the 0D and 1D nanofillers, MXenes show higher efficiency in ionic conductivity enhancement and improvement in the performance of LMBs. The CPE with 3.6 wt% MXene shows the highest ionic conductivity at room temperature (2.2 × 10 −5 S m −1 at 28 °C). An LMB using MCPE with only 1.5 wt% MXene shows rate capability and stability comparable with that of the state-of-the-art CPELMBs. We attribute the excellent performance to the 2D geometry of the filler, the good dispersion of the flakes in the polymer matrix, and the functional group-rich surface.