Gujrati P D, Rane Sagar S, Corsi Andrea
Department of Polymer Science, The University of Akron, Akron, Ohio 44325, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2003 May;67(5 Pt 1):052501. doi: 10.1103/PhysRevE.67.052501. Epub 2003 May 7.
A lattice model of semiflexible linear chains (with equilibrium polydispersity) containing free volume is solved exactly on a Husimi cactus. A metastable liquid (ML) is discovered to exist only at low temperatures and is distinct (and may be disjoint) from the supercooled liquid (SCL) that exists only at high temperatures. The free volume plays a significant role in that the spinodals of the ML and SCL merge and then disappear as the free volume is reduced. The Kauzmann temperature T(K) occurs in the ML without any singularity. At T(MC)>T(K), the ML specific heat has a peak. For infinitely long polymers, the peak height diverges and the free volume vanishes at T(MC), resulting in a continuous liquid-liquid transition. Contrary to the conventional wisdom, both T(K) and T(MC) occur in the ML and not in the SCL.
一个包含自由体积的半柔性线性链（具有平衡多分散性）的晶格模型在胡西米仙人掌图上得到了精确求解。发现一种亚稳态液体（ML）仅在低温下存在，并且与仅在高温下存在的过冷液体（SCL）不同（且可能不相连）。自由体积起着重要作用，因为随着自由体积的减小，ML和SCL的旋节线合并然后消失。考兹曼温度T(K)在ML中出现且没有任何奇异性。在T(MC)>T(K)时，ML的比热容有一个峰值。对于无限长的聚合物，峰值高度发散且自由体积在T(MC)时消失，导致连续的液-液转变。与传统观点相反，T(K)和T(MC)都出现在ML中而不是SCL中。
