Polymer Program, Institute of Materials Science and Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA.
Langmuir. 2011 Sep 6;27(17):11044-51. doi: 10.1021/la2018067. Epub 2011 Aug 2.
Interactions between tethered layers composed of aggrecan (charged bottle-brush) macromolecules are responsible for the molecular origin of cartilage biomechanical behavior. To elucidate the role of the electrostatic forces in interaction between bottle-brush layers, we have performed molecular dynamics simulations of charged and neutral bottle-brush macromolecules tethered to substrates. In the case of charged bottle-brush layers, the disjoining pressure P between two brush layers in salt-free solutions increases with decreasing distance D between substrates as P ∝ D(-1.8). A stronger dependence of the disjoining pressure P on the surface separation D was observed for neutral bottle-brushes, P ∝ D(-4.6), in the same interval of disjoining pressures. These scaling laws for dependence of disjoining pressure P on distance D are due to bending energy of the bottle-brush macromolecules within compressed brush layers. The weaker distance dependence observed in polyelectrolyte bottle-brushes is due to interaction between counterion clouds surrounding the bottle-brush macromolecules preventing strong brush overlap.
由聚集蛋白聚糖（带电瓶刷）大分子组成的束缚层之间的相互作用是软骨生物力学行为的分子起源。为了阐明静电相互作用在瓶刷层之间相互作用中的作用，我们对带电和不带电的瓶刷大分子与基底进行了分子动力学模拟。在带电瓶刷层的情况下，在无盐溶液中两个刷层之间的分离压力 P 随基底之间的距离 D 的减小而增加，即 P∝D(-1.8)。对于中性瓶刷，在相同的分离压力范围内，观察到分离压力 P 对表面分离 D 的更强依赖性，P∝D(-4.6)。这种分离压力 P 随距离 D 的依赖关系的标度律归因于压缩刷层内瓶刷大分子的弯曲能量。在聚电解质瓶刷中观察到的较弱的距离依赖性是由于围绕瓶刷大分子的抗衡离子云的相互作用阻止了强烈的刷重叠。
