Critical fluctuations in fluids and fluid mixtures yield a nonanalytic asymptotic Ising-like critical thermodynamic behavior in terms of power laws with universal exponents. In polymer solutions, the amplitudes of these power laws depend on the degree of polymerization. Nonasymptotic behavior (upon the departure from the critical point) is particularly interesting in the case of polymer solutions, where it is governed by a competition between the correlation length of the critical fluctuations and the radius of gyration of the polymer molecules. If the correlation length is the dominant length scale, Ising-like critical behavior is observed. If, however, the radius of gyration exceeds the correlation length, tricritical behavior with mean-field critical exponents is observed. The Ising-like critical region shrinks with the increase of the polymer molecular weight. In the limit of an infinite degree of polymerization, the Ising-like critical region vanishes, yielding to theta-point tricriticality.

中文翻译：

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聚合物溶液中的临界波动：从临界到三临界的交叉

流体和流体混合物的临界波动根据具有通用指数的幂律产生非解析渐近伊辛样临界热力学行为。在聚合物溶液中，这些幂律的幅度取决于聚合度。非渐近行为（在偏离临界点时）在聚合物溶液的情况下特别有趣，其中它受临界波动的相关长度和聚合物分子的回转半径之间的竞争控制。如果相关长度是主要的长度尺度，则观察到类似 Ising 的临界行为。然而，如果回转半径超过相关长度，则观察到具有平均场临界指数的三临界行为。伊辛样临界区随着聚合物分子量的增加而缩小。在无限聚合度的极限下，类伊辛临界区消失，屈服于 theta 点三临界。