采用温控原子力显微镜方法，在线跟踪了远离临界组成聚甲基丙烯酸甲酯/苯乙烯-丙烯腈无规共聚物（PMMA/SAN）共混薄膜的表面相分离行为，并研究了其动力学规律。结果表明，在SAN含量为70%的样品中观察到了表面相分离行为，其过程可分为早期、中期和晚期3个阶段，分别对应特征化的标度指数：早期结果验证了Cahn线性理论，即标度指数为零；中期相行为主要受“碰撞-扩散”机理控制，因此表现出1/3的标度指数；在相分离后期，流体动力学主导了相区的生长和归并行为，此时标度指数变为2/3。我们的研究结果对于深刻理解高分子相行为具有积极作用，并将对高分子薄膜加工提供必要的指导。
The kinetics of surface phase separation in PMMA/SAN[poly(methyl methacrylate)/poly(styrene-ran-acrylonitrile)] blend film with off-critical component has been investigated by means of in situ AFM(atomic force microscopy). Our results indicate that the surface phase separation observed exists three stages. The exponent of zero in the first stage validate the Cahn theory; In the second one, the phase behaviors are mainly controlled by Brownian-Diffusion, corresponding to the exponent of 1/3. The hydrokinetics in the last stage results in the occurrence of 2/3 as the characteristic exponent. Our results are significant for not only the understanding of phase separation of polymer blend, but also the engineering and application of polymer films.
参考文献
| [1] | Cahn J W, Hilliard J E. Free Energy of a Nonuniform System.I.Interfacial Free Energy[J]. J Chem Phys, 1958, 28(2):258-267. |
| [2] | Brown G, Chakrabarti A. Surface-Directed Spinodal Decomposition in a Two-Dimensional Model[J]. Phys Rev A, 1992, 46(8):4829-4835. |
| [3] | Wu Y, Alexander F J, Lookman T, et al. Effects of Hydrodynamics on Phase Transition Kinetics in Two-Dimensional Binary Fluids[J]. Phys Rev Lett, 1995, 74(19):3852-3855. |
| [4] | Kubota K, Kuwahara N, Eda H, et al. Spinodal Decomposition in a Critical Isobutyric Acid and Water Mixture[J]. Phys Rev A, 1992, 45(15):R3377-R3379. |
| [5] | Wang H, Composto R J. Thin Film Polymer Blends Undergoing Phase Separation and Wetting:Identification of Early, Intermediate, and Late Stages[J]. J Chem Phys, 2000, 113(22):10386-10397. |
| [6] | Wang H, Composto R J. Kinetics of Surface and Interfacial Fluctuations in Phase Separating Polymer Blend Films[J]. Macromolecules, 2002, 35(7):2799-2809. |
| [7] | Lifshitz I M, Slyozov V V. The Kinetics of Precipitation from Supersaturated Solid Solutions[J]. J Phys Chem Solids, 1961, 19(1/2):35-50. |
| [8] | Siggia E D. Late Stages of Spinodal Decomposition in Binary Mixtures[J]. Phys Rev A, 1979, 20(2):595-605. |
| [9] | Wang H, Composto R J. Wetting and Phase Separation in Polymer Blend Films:Identification of Four Thickness Regimes with Distinct Morphological Pathways[J]. Interface Sci, 2003, 11(2):237-248. |
| [10] | Chung H, Composto R J. Breakdown of Dynamic Scaling in Thin Film Binary Liquids Undergoing Phase Separation[J]. Phys Rev Lett, 2004, 92(18):185704. |
| [11] | García R, Pérez R. Dynamic Atomic Force Microscopy Methods[J]. Surf Sci Rep, 2002, 47(6):197-301. |
| [12] | Liao Y G, Su Z H, Ye X G, et al. Kinetics of Surface Phase Separation for PMMA/SAN Thin Films Studied by in Situ Atomic Force Microscopy[J]. Macromolecules, 2005, 38(2):211-215. |
| [13] | Liao Y G, Su Z H, Sun Z Y, et al. Dewetting and Phase Behaviors for Ultrathin Films of Polymer Blend[J]. Macromol Rapid Commun, 2006, 27(5):351-355. |
| [14] | Takeno H, Hashimoto T. Intermittency of Droplet Growth in Phase Separation of Off-critical Polymer Mixtures[J]. J Chem Phys, 1998, 108(3):1225-1233. |
| [15] | Furukaua H. A Dynamic Scaling Assumption for Phase Separation[J]. Adv Phys, 1985, 34(6):703-750. |
| [16] | Furukaua H. Scaling and the Small-Wave-Vector Limit of the Form Factor in Phase-Ordering Dynamics[J]. Phys Rev Lett, 1988, 61(9):1135-1138. |
| [17] | You J C, Shi T F, Liao Y G, et al. Temperature Dependence of Surface Composition and Morphology in Polymer Blend Film[J]. Polymer, 2008, 49(20):4456-4461. |
| [18] | Liao Y G, You J C, Li X, et al. Annealing and Quasi-Quenching Processes of Phase-Separated PMMA/SAN Thin Film Studied by in situ AFM with Hot Stage[J]. Chem J Chinese Univ, 2005, 26(9):1777-1779. |
| [19] | Bray A J. Theory of Phase-Ordering Kinetics[J]. Adv Phys, 1994, 43(3):357-459. |
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