远离临界组成的聚甲基丙烯酸甲酯/苯乙烯-丙烯腈无规共聚物共混薄膜表面相分离动力学

Kinetics of Surface Phase Separation in Poly(methyl methacrylate)/Poly(styrene-ran-acrylonitrile)Blend Film with Off-critical Component

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.