Force Regulation by Sequence-Defined Polyelectrolytes

Abstract

In order to achieve multifunctional adhesive materials with water and salt tolerance, it is crucial to understand the electrostatic mechanism of nanoconfined polyelectrolytes (PEs) with specific monomer sequences. Here, using density functional theory (DFT), self-consistent field theory (SCFT), and molecular dynamics (MD) simulation, we analyzed the microstructures of sequence-defined PEs confined in a nanoscale slit and the relationship between sequences and the attractive forces induced by the nanoconfined PEs. Among three sequence-defined (alternating [A], tapered [T], and reversely tapered [R] sequence) PEs, due to the formation of stable multibridge conformations, [A]-sequence PEs induce the strongest attractive forces even in the case with high salt concentrations, i.e., the best salt tolerance. It is worth emphasizing that salt enhancement of attractive forces occurs in systems with [A]-sequence PEs due to the screening of repulsive interactions between PE chains. In contrast, in systems with [T]-sequence PEs, the shielding of the attractive interactions between surfaces and charged monomers significantly attenuates the attractive forces between surfaces at high salt concentrations. In addition, the strength of attractive forces can be regulated by block number N_b. At high charge fractions such as f_c = 0.5, the attractive forces induced by [A]-sequence PEs become stronger with N_b, while at low charge fractions such as f_c = 0.2, the attractive forces vary nonmonotonically with N_b due to the electrostatic correlations.