Medidhi Koteswara Rao, Padmanabhan Venkat
Department of Chemical Engineering, Tennessee Technological University, Cookeville, Tennessee 38501, USA.
Soft Matter. 2021 Mar 28;17(12):3455-3462. doi: 10.1039/d0sm02142c. Epub 2021 Mar 2.
The effect of charges and hydrogen bonding on viscosity in solutions containing polyelectrolyte-grafted nanoparticles (PENP) has been investigated using molecular dynamics (MD) simulations. The electrostatic interaction between the charged monomers on the grafted chains, which increases with the degree of ionization, causes the grafted polymers to stretch and increases the hydrodynamic size of the nanoparticles. The viscosity of the solution is partially governed by the balance between the entanglement of grafted chains and the electrostatic repulsion. Moreover, the charge-assisted hydrogen bonds between the monomers of different particles further enhance the viscosity of the solution. For shorter grafted chains, a majority of hydrogen bonds are formed within the same particle and thus show no significant enhancement in viscosity. The addition of polymer chains with hydrogen bonding sites has been shown to bridge multiple nanoparticles, creating a network structure, that increases viscosity. The chain stiffness has been shown to have a direct correlation with bridging and thus the viscosity of the solution.
利用分子动力学（MD）模拟研究了电荷和氢键对含聚电解质接枝纳米颗粒（PENP）溶液粘度的影响。接枝链上带电单体之间的静电相互作用随电离程度增加，使接枝聚合物伸展并增大纳米颗粒的流体力学尺寸。溶液的粘度部分由接枝链的缠结和静电排斥之间的平衡决定。此外，不同颗粒单体之间的电荷辅助氢键进一步提高了溶液的粘度。对于较短的接枝链，大多数氢键在同一颗粒内形成，因此粘度没有显著提高。已表明添加具有氢键位点的聚合物链可桥接多个纳米颗粒，形成网络结构，从而增加粘度。已表明链刚度与桥接直接相关，进而与溶液的粘度相关。
