The collective dynamics of 25 wt% poly(N-isopropylacrylamide) (PNIPAM) solutions in water or an 80:20 v/v water/methanol mixture are investigated in the one-phase region in dependence on pressure and temperature using dynamic light scattering. Throughout, two dynamic modes are observed, the fast one corresponding to the relaxation of the chain segments within the polymer blobs and the slow one to the relaxation of the blobs. A pressure scan in the one-phase region on an aqueous solution at 34.0 °C, i.e., slightly below the maximum of the coexistence line, reveals that the dynamic correlation length of the fast mode increases when the left and the right branch of the coexistence line are approached. Thus, the chains are rather swollen far away from the coexistence line, but contracted near the phase transition. Temperature scans of solutions in neat H₂O or in H₂O/CD₃OD at 0.1, 130, and 200 MPa reveal that the dynamic correlation length of the fast mode shows critical behavior. However, the critical exponents are significantly larger than the value predicted by mean-field theory for the static correlation length, ν = 0.5, and the exponent is significantly larger for the solution in the H₂O/CD₃OD mixture than in neat H₂O.

25 wt% poly( N使用动态光散射在单相区域中根据压力和温度研究了在水中或 80:20 v/v 水/甲醇混合物中的异丙基丙烯酰胺 (PNIPAM) 溶液。在整个过程中，观察到两种动态模式，快速模式对应于聚合物斑点内链段的松弛，而慢速模式对应于斑点的松弛。在 34.0 °C 的水溶液上进行单相区的压力扫描，即略低于共存线的最大值，表明当共存的左右分支时，快速模式的动态相关长度增加行已接近。因此，链在远离共存线的地方相当膨胀，但在相变附近收缩。纯 H _{2溶液的温度扫描}O 或 H ₂ O/CD ₃ OD 在 0.1、130 和 200 MPa 下表明快速模式的动态相关长度表现出临界行为。然而，对于静态相关长度ν  = 0.5，临界指数明显大于平均场理论预测的值，并且 H ₂ O/CD ₃ OD 混合物溶液的指数明显大于纯 H溶液的指数。 ₂ O。