Leibniz-Institut für Polymerforschung Dresden, Hohe Strasse 6, 01069 Dresden, Germany.
Phys Rev Lett. 2010 Apr 30;104(17):177801. doi: 10.1103/PhysRevLett.104.177801. Epub 2010 Apr 26.
The tube model of entangled chains is applied to compute segment fluctuations and segmental orientational order in polymer networks. The entanglement length N{e} is extracted directly from monomer fluctuations without constructing a primitive path. Sliding motion of monomers along the tube axis leads to reduction of segmental order along the chain. For network strands of length N>>N{e}, the average segmental order decreases approximately (N{e}N);{-1/2} in marked contrast to the 1/N{e} contribution of entanglements to network elasticity. As a consequence, network modulus is not proportional to segmental order in entangled polymer networks. Monte Carlo simulations over a wide range of molecular weights are in quantitative agreement with our theoretical predictions. The impact of entanglements on these properties is directly tested by comparing with simulations where entanglement constraints are switched off.
纠缠链的管模型被应用于计算聚合物网络中的链段波动和链段取向序。缠结长度 N{e} 直接从单体波动中提取，而无需构建原始路径。单体沿着管轴的滑动运动导致链上链段取向序的降低。对于长度为 N>>N{e} 的网络链，平均链段取向序大约降低为 (N{e}N);{-1/2}，与缠结对网络弹性的 1/N{e} 贡献形成鲜明对比。因此，在缠结聚合物网络中，网络模量与链段取向序不成正比。广泛的分子量范围内的蒙特卡罗模拟与我们的理论预测定量一致。通过与关闭缠结约束的模拟进行比较，直接测试了缠结对这些性质的影响。
