论文标题
半辅助聚合物和纤维的两阶段凝固
Two-stage athermal solidification of semiflexible polymers and fibers
论文作者
论文摘要
我们研究了模型在Athermal Athermal Aquasistatic压缩下自由旋转聚合物的固化如何随键角$θ_0$而变化。所有系统都经历了两个离散的一阶式过渡：纠缠$ ϕ = ϕ_e（θ_0）$，其次是$ ϕ = ϕ_j（θ_0）\ simeq（4/3 \ pm 1/10）ϕ__e（θ_0）$。对于$ ϕ <ϕ_e（θ_0）$，系统处于“气体”阶段，所有链条都保持自由进行翻译和重新定位。对于$ ϕ_e（θ_0）\ leq ϕ \ leq ϕ_j（θ_0）$，系统处于液体状相处，其中链被纠缠。在此阶段，链的刚体状运动被阻塞，但它们仍然可以通过二面旋转局部放松，因此能量和压力仍然非常小。二面体松弛机制适应进一步压缩的能力变得筋疲力尽，并且系统缩放为$ ϕ_j（θ_0）$。在$ ϕ_j $上方，散装模量与压力$ p $线性增加，而不是不连续跳跃，表明这些系统通过刚度渗透固化。可以通过链的有效纵横比$α_ {\ rm eff} $来表征能量和压力的特征以上$ ϕ_j（θ_0）$。大 - $α_ {\ rm eff} $（small-$θ_0$）系统的干扰是弯曲的主导，与在由直纤维组成的系统中观察到的系统相似。小-$α_ {\ rm eff} $（大$θ_0$）系统的干扰由单个链的二二二二二二二二二二脑塌陷成紧凑的四面体样结构的程度。对于中级$θ_0$，在整个压缩过程中，链保持在高度无序的球状构型中；当纠缠的小球甚至无法在本地放松彼此时，就会发生障碍。
We study how solidification of model freely rotating polymers under athermal quasistatic compression varies with their bond angle $θ_0$. All systems undergo two discrete, first-order-like transitions: entanglement at $ϕ= ϕ_E(θ_0)$ followed by jamming at $ϕ= ϕ_J(θ_0) \simeq (4/3 \pm 1/10)ϕ_E(θ_0)$. For $ϕ< ϕ_E(θ_0)$, systems are in a "gas" phase wherein all chains remain free to translate and reorient. For $ϕ_E(θ_0) \leq ϕ\leq ϕ_J(θ_0)$, systems are in a liquid-like phase wherein chains are entangled. In this phase, chains' rigid-body-like motion is blocked, yet they can still locally relax via dihedral rotations, and hence energy and pressure remain extremely small. The ability of dihedral relaxation mechanisms to accommodate further compression becomes exhausted, and systems rigidify, at $ϕ_J(θ_0)$. At and slightly above $ϕ_J$, the bulk moduli increase linearly with the pressure $P$ rather than jumping discontinuously, indicating these systems solidify via rigidity percolation. The character of the energy and pressure increases above $ϕ_J(θ_0)$ can be characterized via chains' effective aspect ratio $α_{\rm eff}$. Large-$α_{\rm eff}$ (small-$θ_0$) systems' jamming is bending-dominated and is similar to that observed in systems composed of straight fibers. Small-$α_{\rm eff}$ (large-$θ_0$) systems' jamming is dominated by the degree to which individual chains' dihedrals can collapse into compact, tetrahedron-like structures. For intermediate $θ_0$, chains remain in highly disordered globule-like configurations throughout the compression process; jamming occurs when entangled globules can no longer even locally relax away from one another.
